netdata/health/health.c

// SPDX-License-Identifier: GPL-3.0-or-later

#include "health.h"

#define WORKER_HEALTH_JOB_RRD_LOCK              0
#define WORKER_HEALTH_JOB_HOST_LOCK             1
#define WORKER_HEALTH_JOB_DB_QUERY              2
#define WORKER_HEALTH_JOB_CALC_EVAL             3
#define WORKER_HEALTH_JOB_WARNING_EVAL          4
#define WORKER_HEALTH_JOB_CRITICAL_EVAL         5
#define WORKER_HEALTH_JOB_ALARM_LOG_ENTRY       6
#define WORKER_HEALTH_JOB_ALARM_LOG_PROCESS     7
#define WORKER_HEALTH_JOB_DELAYED_INIT_RRDSET   8
#define WORKER_HEALTH_JOB_DELAYED_INIT_RRDDIM   9

#if WORKER_UTILIZATION_MAX_JOB_TYPES < 10
#error WORKER_UTILIZATION_MAX_JOB_TYPES has to be at least 10
#endif

unsigned int default_health_enabled = 1;
char *silencers_filename;
SIMPLE_PATTERN *conf_enabled_alarms = NULL;
DICTIONARY *health_rrdvars;

static bool prepare_command(BUFFER *wb,
                            const char *exec,
                            const char *recipient,
                            const char *registry_hostname,
                            uint32_t unique_id,
                            uint32_t alarm_id,
                            uint32_t alarm_event_id,
                            uint32_t when,
                            const char *alert_name,
                            const char *alert_chart_name,
                            const char *alert_family,
                            const char *new_status,
                            const char *old_status,
                            NETDATA_DOUBLE new_value,
                            NETDATA_DOUBLE old_value,
                            const char *alert_source,
                            uint32_t duration,
                            uint32_t non_clear_duration,
                            const char *alert_units,
                            const char *alert_info,
                            const char *new_value_string,
                            const char *old_value_string,
                            const char *source,
                            const char *error_msg,
                            int n_warn,
                            int n_crit,
                            const char *warn_alarms,
                            const char *crit_alarms,
                            const char *classification,
                            const char *edit_command,
                            const char *machine_guid)
{
    char buf[8192];
    size_t n = 8192 - 1;

    buffer_strcat(wb, "exec");

    if (!sanitize_command_argument_string(buf, exec, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, recipient, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, registry_hostname, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    buffer_sprintf(wb, " '%u'", unique_id);

    buffer_sprintf(wb, " '%u'", alarm_id);

    buffer_sprintf(wb, " '%u'", alarm_event_id);

    buffer_sprintf(wb, " '%u'", when);

    if (!sanitize_command_argument_string(buf, alert_name, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, alert_chart_name, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, alert_family, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, new_status, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, old_status, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    buffer_sprintf(wb, " '" NETDATA_DOUBLE_FORMAT_ZERO "'", new_value);

    buffer_sprintf(wb, " '" NETDATA_DOUBLE_FORMAT_ZERO "'", old_value);

    if (!sanitize_command_argument_string(buf, alert_source, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    buffer_sprintf(wb, " '%u'", duration);

    buffer_sprintf(wb, " '%u'", non_clear_duration);

    if (!sanitize_command_argument_string(buf, alert_units, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, alert_info, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, new_value_string, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, old_value_string, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, source, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, error_msg, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    buffer_sprintf(wb, " '%d'", n_warn);

    buffer_sprintf(wb, " '%d'", n_crit);

    if (!sanitize_command_argument_string(buf, warn_alarms, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, crit_alarms, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, classification, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, edit_command, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    if (!sanitize_command_argument_string(buf, machine_guid, n))
        return false;
    buffer_sprintf(wb, " '%s'", buf);

    return true;
}

// the queue of executed alarm notifications that haven't been waited for yet
static struct {
    ALARM_ENTRY *head; // oldest
    ALARM_ENTRY *tail; // latest
} alarm_notifications_in_progress = {NULL, NULL};

typedef struct active_alerts {
    char *name;
    time_t last_status_change;
    RRDCALC_STATUS status;
} active_alerts_t;

static inline void enqueue_alarm_notify_in_progress(ALARM_ENTRY *ae)
{
    ae->prev_in_progress = NULL;
    ae->next_in_progress = NULL;

    if (NULL != alarm_notifications_in_progress.tail) {
        ae->prev_in_progress = alarm_notifications_in_progress.tail;
        alarm_notifications_in_progress.tail->next_in_progress = ae;
    }
    if (NULL == alarm_notifications_in_progress.head) {
        alarm_notifications_in_progress.head = ae;
    }
    alarm_notifications_in_progress.tail = ae;

}

static inline void unlink_alarm_notify_in_progress(ALARM_ENTRY *ae)
{
    struct alarm_entry *prev = ae->prev_in_progress;
    struct alarm_entry *next = ae->next_in_progress;

    if (NULL != prev) {
        prev->next_in_progress = next;
    }
    if (NULL != next) {
        next->prev_in_progress = prev;
    }
    if (ae == alarm_notifications_in_progress.head) {
        alarm_notifications_in_progress.head = next;
    }
    if (ae == alarm_notifications_in_progress.tail) {
        alarm_notifications_in_progress.tail = prev;
    }
}
// ----------------------------------------------------------------------------
// health initialization

/**
 * User Config directory
 *
 * Get the config directory for health and return it.
 *
 * @return a pointer to the user config directory
 */
inline char *health_user_config_dir(void) {
    char buffer[FILENAME_MAX + 1];
    snprintfz(buffer, FILENAME_MAX, "%s/health.d", netdata_configured_user_config_dir);
    return config_get(CONFIG_SECTION_DIRECTORIES, "health config", buffer);
}

/**
 * Stock Config Directory
 *
 * Get the Stock config directory and return it.
 *
 * @return a pointer to the stock config directory.
 */
inline char *health_stock_config_dir(void) {
    char buffer[FILENAME_MAX + 1];
    snprintfz(buffer, FILENAME_MAX, "%s/health.d", netdata_configured_stock_config_dir);
    return config_get(CONFIG_SECTION_DIRECTORIES, "stock health config", buffer);
}

/**
 * Silencers init
 *
 * Function used to initialize the silencer structure.
 */
static void health_silencers_init(void) {
    FILE *fd = fopen(silencers_filename, "r");
    if (fd) {
        fseek(fd, 0 , SEEK_END);
        off_t length = (off_t) ftell(fd);
        fseek(fd, 0 , SEEK_SET);

        if (length > 0 && length < HEALTH_SILENCERS_MAX_FILE_LEN) {
            char *str = mallocz((length+1)* sizeof(char));
            if(str) {
                size_t copied;
                copied = fread(str, sizeof(char), length, fd);
                if (copied == (length* sizeof(char))) {
                    str[length] = 0x00;
                    json_parse(str, NULL, health_silencers_json_read_callback);
                    info("Parsed health silencers file %s", silencers_filename);
                } else {
                    error("Cannot read the data from health silencers file %s", silencers_filename);
                }
                freez(str);
            }
        } else {
            error(
                "Health silencers file %s has the size %" PRId64 " that is out of range[ 1 , %d ]. Aborting read.",
                silencers_filename,
                (int64_t)length,
                HEALTH_SILENCERS_MAX_FILE_LEN);
        }
        fclose(fd);
    } else {
        info("Cannot open the file %s, so Netdata will work with the default health configuration.",silencers_filename);
    }
}

/**
 * Health Init
 *
 * Initialize the health thread.
 */
void health_init(void) {
    debug(D_HEALTH, "Health configuration initializing");

    if(!(default_health_enabled = (unsigned int)config_get_boolean(CONFIG_SECTION_HEALTH, "enabled", default_health_enabled))) {
        debug(D_HEALTH, "Health is disabled.");
        return;
    }

    health_silencers_init();
}

// ----------------------------------------------------------------------------
// re-load health configuration

/**
 * Reload host
 *
 * Reload configuration for a specific host.
 *
 * @param host the structure of the host that the function will reload the configuration.
 */
static void health_reload_host(RRDHOST *host) {
    if(unlikely(!host->health.health_enabled) && !rrdhost_flag_check(host, RRDHOST_FLAG_INITIALIZED_HEALTH))
        return;

    log_health("[%s]: Reloading health.", rrdhost_hostname(host));

    char *user_path = health_user_config_dir();
    char *stock_path = health_stock_config_dir();

    // free all running alarms
    rrdcalc_delete_all(host);
    rrdcalctemplate_delete_all(host);

    // invalidate all previous entries in the alarm log
    netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);
    ALARM_ENTRY *t;
    for(t = host->health_log.alarms ; t ; t = t->next) {
        if(t->new_status != RRDCALC_STATUS_REMOVED)
            t->flags |= HEALTH_ENTRY_FLAG_UPDATED;
    }
    netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);

    // reset all thresholds to all charts
    RRDSET *st;
    rrdset_foreach_read(st, host) {
        st->green = NAN;
        st->red = NAN;
    }
    rrdset_foreach_done(st);

    // load the new alarms
    health_readdir(host, user_path, stock_path, NULL);

    //Discard alarms with labels that do not apply to host
    rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(host);

    // link the loaded alarms to their charts
    rrdset_foreach_write(st, host) {
        if (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED))
            continue;

        rrdcalc_link_matching_alerts_to_rrdset(st);
        rrdcalctemplate_link_matching_templates_to_rrdset(st);
    }
    rrdset_foreach_done(st);

#ifdef ENABLE_ACLK
    if (netdata_cloud_setting) {
        struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
        if (likely(wc)) {
            wc->alert_queue_removed = SEND_REMOVED_AFTER_HEALTH_LOOPS;
        }
    }
#endif
}

/**
 * Reload
 *
 * Reload the host configuration for all hosts.
 */
void health_reload(void) {
    sql_refresh_hashes();

    RRDHOST *host;
    dfe_start_reentrant(rrdhost_root_index, host){
        health_reload_host(host);
    }
    dfe_done(host);
}

// ----------------------------------------------------------------------------
// health main thread and friends

static inline RRDCALC_STATUS rrdcalc_value2status(NETDATA_DOUBLE n) {
    if(isnan(n) || isinf(n)) return RRDCALC_STATUS_UNDEFINED;
    if(n) return RRDCALC_STATUS_RAISED;
    return RRDCALC_STATUS_CLEAR;
}

#define ACTIVE_ALARMS_LIST_EXAMINE 500
#define ACTIVE_ALARMS_LIST 15

static inline int compare_active_alerts(const void * a, const void * b) {
    active_alerts_t *active_alerts_a = (active_alerts_t *)a;
    active_alerts_t *active_alerts_b = (active_alerts_t *)b;

    return ( active_alerts_b->last_status_change - active_alerts_a->last_status_change );
}

static inline void health_alarm_execute(RRDHOST *host, ALARM_ENTRY *ae) {
    ae->flags |= HEALTH_ENTRY_FLAG_PROCESSED;

    if(unlikely(ae->new_status < RRDCALC_STATUS_CLEAR)) {
        // do not send notifications for internal statuses
        debug(D_HEALTH, "Health not sending notification for alarm '%s.%s' status %s (internal statuses)", ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));
        goto done;
    }

    if(unlikely(ae->new_status <= RRDCALC_STATUS_CLEAR && (ae->flags & HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION))) {
        // do not send notifications for disabled statuses
        debug(D_HEALTH, "Health not sending notification for alarm '%s.%s' status %s (it has no-clear-notification enabled)", ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));
        log_health("[%s]: Health not sending notification for alarm '%s.%s' status %s (it has no-clear-notification enabled)", rrdhost_hostname(host), ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));
        // mark it as run, so that we will send the same alarm if it happens again
        goto done;
    }

    // find the previous notification for the same alarm
    // which we have run the exec script
    // exception: alarms with HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION set
    RRDCALC_STATUS last_executed_status = -3;
    if(likely(!(ae->flags & HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION))) {
        int ret = sql_health_get_last_executed_event(host, ae, &last_executed_status);

        if (likely(ret == 1)) {
            // we have executed this alarm notification in the past
            if(last_executed_status == ae->new_status) {
                // don't send the notification for the same status again
                debug(D_HEALTH, "Health not sending again notification for alarm '%s.%s' status %s", ae_chart_name(ae), ae_name(ae)
                      , rrdcalc_status2string(ae->new_status));
                log_health("[%s]: Health not sending again notification for alarm '%s.%s' status %s", rrdhost_hostname(host), ae_chart_name(ae), ae_name(ae)
                      , rrdcalc_status2string(ae->new_status));
                goto done;
            }
        }
        else {
            // we have not executed this alarm notification in the past
            // so, don't send CLEAR notifications
            if(unlikely(ae->new_status == RRDCALC_STATUS_CLEAR)) {
                if((!(ae->flags & HEALTH_ENTRY_RUN_ONCE)) || (ae->flags & HEALTH_ENTRY_RUN_ONCE && ae->old_status < RRDCALC_STATUS_RAISED) ) {
                    debug(D_HEALTH, "Health not sending notification for first initialization of alarm '%s.%s' status %s"
                    , ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));
                    goto done;
                }
            }
        }
    }

    // Check if alarm notifications are silenced
    if (ae->flags & HEALTH_ENTRY_FLAG_SILENCED) {
        log_health("[%s]: Health not sending notification for alarm '%s.%s' status %s (command API has disabled notifications)", rrdhost_hostname(host), ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));
        goto done;
    }

    log_health("[%s]: Sending notification for alarm '%s.%s' status %s.", rrdhost_hostname(host), ae_chart_name(ae), ae_name(ae), rrdcalc_status2string(ae->new_status));

    const char *exec      = (ae->exec)      ? ae_exec(ae)      : string2str(host->health.health_default_exec);
    const char *recipient = (ae->recipient) ? ae_recipient(ae) : string2str(host->health.health_default_recipient);

    int n_warn=0, n_crit=0;
    RRDCALC *rc;
    EVAL_EXPRESSION *expr=NULL;
    BUFFER *warn_alarms, *crit_alarms;
    active_alerts_t *active_alerts = callocz(ACTIVE_ALARMS_LIST_EXAMINE, sizeof(active_alerts_t));

    warn_alarms = buffer_create(NETDATA_WEB_RESPONSE_INITIAL_SIZE, &netdata_buffers_statistics.buffers_health);
    crit_alarms = buffer_create(NETDATA_WEB_RESPONSE_INITIAL_SIZE, &netdata_buffers_statistics.buffers_health);

    foreach_rrdcalc_in_rrdhost_read(host, rc) {
        if(unlikely(!rc->rrdset || !rc->rrdset->last_collected_time.tv_sec))
            continue;

        if(unlikely((n_warn + n_crit) >= ACTIVE_ALARMS_LIST_EXAMINE))
            break;

        if (unlikely(rc->status == RRDCALC_STATUS_WARNING)) {
            if (likely(ae->alarm_id != rc->id) || likely(ae->alarm_event_id != rc->next_event_id - 1)) {
                active_alerts[n_warn+n_crit].name = (char *)rrdcalc_name(rc);
                active_alerts[n_warn+n_crit].last_status_change = rc->last_status_change;
                active_alerts[n_warn+n_crit].status = rc->status;
                n_warn++;
            } else if (ae->alarm_id == rc->id)
                expr = rc->warning;
        } else if (unlikely(rc->status == RRDCALC_STATUS_CRITICAL)) {
            if (likely(ae->alarm_id != rc->id) || likely(ae->alarm_event_id != rc->next_event_id - 1)) {
                active_alerts[n_warn+n_crit].name = (char *)rrdcalc_name(rc);
                active_alerts[n_warn+n_crit].last_status_change = rc->last_status_change;
                active_alerts[n_warn+n_crit].status = rc->status;
                n_crit++;
            } else if (ae->alarm_id == rc->id)
                expr = rc->critical;
        } else if (unlikely(rc->status == RRDCALC_STATUS_CLEAR)) {
            if (ae->alarm_id == rc->id)
                expr = rc->warning;
        }
    }
    foreach_rrdcalc_in_rrdhost_done(rc);

    if (n_warn+n_crit>1)
        qsort (active_alerts, n_warn+n_crit, sizeof(active_alerts_t), compare_active_alerts);

    int count_w = 0, count_c = 0;
    while (count_w + count_c < n_warn + n_crit && count_w + count_c < ACTIVE_ALARMS_LIST) {
        if (active_alerts[count_w+count_c].status == RRDCALC_STATUS_WARNING) {
            if (count_w)
                buffer_strcat(warn_alarms, ",");
            buffer_strcat(warn_alarms, active_alerts[count_w+count_c].name);
            buffer_strcat(warn_alarms, "=");
            buffer_snprintf(warn_alarms, 11, "%"PRId64"", (int64_t)active_alerts[count_w+count_c].last_status_change);
            count_w++;
        }
        else if (active_alerts[count_w+count_c].status == RRDCALC_STATUS_CRITICAL) {
            if (count_c)
                buffer_strcat(crit_alarms, ",");
            buffer_strcat(crit_alarms, active_alerts[count_w+count_c].name);
            buffer_strcat(crit_alarms, "=");
            buffer_snprintf(crit_alarms, 11, "%"PRId64"", (int64_t)active_alerts[count_w+count_c].last_status_change);
            count_c++;
        }
    }

    char *edit_command = ae->source ? health_edit_command_from_source(ae_source(ae)) : strdupz("UNKNOWN=0=UNKNOWN");

    BUFFER *wb = buffer_create(8192, &netdata_buffers_statistics.buffers_health);
    bool ok = prepare_command(wb,
                              exec,
                              recipient,
                              rrdhost_registry_hostname(host),
                              ae->unique_id,
                              ae->alarm_id,
                              ae->alarm_event_id,
                              (unsigned long)ae->when,
                              ae_name(ae),
                              ae->chart?ae_chart_name(ae):"NOCHART",
                              ae->family?ae_family(ae):"NOFAMILY",
                              rrdcalc_status2string(ae->new_status),
                              rrdcalc_status2string(ae->old_status),
                              ae->new_value,
                              ae->old_value,
                              ae->source?ae_source(ae):"UNKNOWN",
                              (uint32_t)ae->duration,
                              (uint32_t)ae->non_clear_duration,
                              ae_units(ae),
                              ae_info(ae),
                              ae_new_value_string(ae),
                              ae_old_value_string(ae),
                              (expr && expr->source)?expr->source:"NOSOURCE",
                              (expr && expr->error_msg)?buffer_tostring(expr->error_msg):"NOERRMSG",
                              n_warn,
                              n_crit,
                              buffer_tostring(warn_alarms),
                              buffer_tostring(crit_alarms),
                              ae->classification?ae_classification(ae):"Unknown",
                              edit_command,
                              host != localhost ? host->machine_guid:"");

    const char *command_to_run = buffer_tostring(wb);
    if (ok) {
        ae->flags |= HEALTH_ENTRY_FLAG_EXEC_RUN;
        ae->exec_run_timestamp = now_realtime_sec(); /* will be updated by real time after spawning */

        debug(D_HEALTH, "executing command '%s'", command_to_run);
        ae->flags |= HEALTH_ENTRY_FLAG_EXEC_IN_PROGRESS;
        ae->exec_spawn_serial = spawn_enq_cmd(command_to_run);
        enqueue_alarm_notify_in_progress(ae);
        health_alarm_log_save(host, ae);
    } else {
        error("Failed to format command arguments");
    }

    buffer_free(wb);
    freez(edit_command);
    buffer_free(warn_alarms);
    buffer_free(crit_alarms);
    freez(active_alerts);

    return; //health_alarm_wait_for_execution
done:
    health_alarm_log_save(host, ae);
}

static inline void health_alarm_wait_for_execution(ALARM_ENTRY *ae) {
    if (!(ae->flags & HEALTH_ENTRY_FLAG_EXEC_IN_PROGRESS))
        return;

    spawn_wait_cmd(ae->exec_spawn_serial, &ae->exec_code, &ae->exec_run_timestamp);
    debug(D_HEALTH, "done executing command - returned with code %d", ae->exec_code);
    ae->flags &= ~HEALTH_ENTRY_FLAG_EXEC_IN_PROGRESS;

    if(ae->exec_code != 0)
        ae->flags |= HEALTH_ENTRY_FLAG_EXEC_FAILED;

    unlink_alarm_notify_in_progress(ae);
}

static inline void health_process_notifications(RRDHOST *host, ALARM_ENTRY *ae) {
    debug(D_HEALTH, "Health alarm '%s.%s' = " NETDATA_DOUBLE_FORMAT_AUTO " - changed status from %s to %s",
         ae->chart?ae_chart_name(ae):"NOCHART", ae_name(ae),
         ae->new_value,
         rrdcalc_status2string(ae->old_status),
         rrdcalc_status2string(ae->new_status)
    );

    health_alarm_execute(host, ae);
}

static inline void health_alarm_log_process(RRDHOST *host) {
    uint32_t first_waiting = (host->health_log.alarms)?host->health_log.alarms->unique_id:0;
    time_t now = now_realtime_sec();

    netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);

    ALARM_ENTRY *ae;
    for(ae = host->health_log.alarms; ae && ae->unique_id >= host->health_last_processed_id; ae = ae->next) {
        if(likely(!(ae->flags & HEALTH_ENTRY_FLAG_IS_REPEATING))) {
            if(unlikely(
                    !(ae->flags & HEALTH_ENTRY_FLAG_PROCESSED) &&
                    !(ae->flags & HEALTH_ENTRY_FLAG_UPDATED)
            )) {
                if(unlikely(ae->unique_id < first_waiting))
                    first_waiting = ae->unique_id;

                if(likely(now >= ae->delay_up_to_timestamp))
                    health_process_notifications(host, ae);
            }
        }
    }

    netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);

    // remember this for the next iteration
    host->health_last_processed_id = first_waiting;

    //delete those that are updated, no in progress execution, and is not repeating
    netdata_rwlock_wrlock(&host->health_log.alarm_log_rwlock);

    ALARM_ENTRY *prev = NULL, *next = NULL;
    for(ae = host->health_log.alarms; ae ; ae = next) {
        next = ae->next; // set it here, for the next iteration

        if((likely(!(ae->flags & HEALTH_ENTRY_FLAG_IS_REPEATING)) &&
           (ae->flags & HEALTH_ENTRY_FLAG_UPDATED) &&
           (ae->flags & HEALTH_ENTRY_FLAG_SAVED) &&
           !(ae->flags & HEALTH_ENTRY_FLAG_EXEC_IN_PROGRESS))
            ||
           ((ae->new_status == RRDCALC_STATUS_REMOVED) &&
           (ae->flags & HEALTH_ENTRY_FLAG_SAVED) &&
           (ae->when + 3600 < now_realtime_sec())))
            {

            if(host->health_log.alarms == ae) {
                host->health_log.alarms = next;
                // prev is also NULL here
            }
            else {
                prev->next = next;
                // prev should not be touched here - we need it for the next iteration
                // because we may have to also remove the next item
            }

            health_alarm_log_free_one_nochecks_nounlink(ae);
        }
        else
            prev = ae;
    }

    netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
}

static inline int rrdcalc_isrunnable(RRDCALC *rc, time_t now, time_t *next_run) {
    if(unlikely(!rc->rrdset)) {
        debug(D_HEALTH, "Health not running alarm '%s.%s'. It is not linked to a chart.", rrdcalc_chart_name(rc), rrdcalc_name(rc));
        return 0;
    }

    if(unlikely(rc->next_update > now)) {
        if (unlikely(*next_run > rc->next_update)) {
            // update the next_run time of the main loop
            // to run this alarm precisely the time required
            *next_run = rc->next_update;
        }

        debug(D_HEALTH, "Health not examining alarm '%s.%s' yet (will do in %d secs).", rrdcalc_chart_name(rc), rrdcalc_name(rc), (int) (rc->next_update - now));
        return 0;
    }

    if(unlikely(!rc->update_every)) {
        debug(D_HEALTH, "Health not running alarm '%s.%s'. It does not have an update frequency", rrdcalc_chart_name(rc), rrdcalc_name(rc));
        return 0;
    }

    if(unlikely(rrdset_flag_check(rc->rrdset, RRDSET_FLAG_OBSOLETE))) {
        debug(D_HEALTH, "Health not running alarm '%s.%s'. The chart has been marked as obsolete", rrdcalc_chart_name(rc), rrdcalc_name(rc));
        return 0;
    }

    if(unlikely(rrdset_flag_check(rc->rrdset, RRDSET_FLAG_ARCHIVED))) {
        debug(D_HEALTH, "Health not running alarm '%s.%s'. The chart has been marked as archived", rrdcalc_chart_name(rc), rrdcalc_name(rc));
        return 0;
    }

    if(unlikely(!rc->rrdset->last_collected_time.tv_sec || rc->rrdset->counter_done < 2)) {
        debug(D_HEALTH, "Health not running alarm '%s.%s'. Chart is not fully collected yet.", rrdcalc_chart_name(rc), rrdcalc_name(rc));
        return 0;
    }

    int update_every = rc->rrdset->update_every;
    time_t first = rrdset_first_entry_s(rc->rrdset);
    time_t last = rrdset_last_entry_s(rc->rrdset);

    if(unlikely(now + update_every < first /* || now - update_every > last */)) {
        debug(D_HEALTH
              , "Health not examining alarm '%s.%s' yet (wanted time is out of bounds - we need %lu but got %lu - %lu)."
              , rrdcalc_chart_name(rc), rrdcalc_name(rc), (unsigned long) now, (unsigned long) first
              , (unsigned long) last);
        return 0;
    }

    if(RRDCALC_HAS_DB_LOOKUP(rc)) {
        time_t needed = now + rc->before + rc->after;

        if(needed + update_every < first || needed - update_every > last) {
            debug(D_HEALTH
                  , "Health not examining alarm '%s.%s' yet (not enough data yet - we need %lu but got %lu - %lu)."
                  , rrdcalc_chart_name(rc), rrdcalc_name(rc), (unsigned long) needed, (unsigned long) first
                  , (unsigned long) last);
            return 0;
        }
    }

    return 1;
}

static inline int check_if_resumed_from_suspension(void) {
    static usec_t last_realtime = 0, last_monotonic = 0;
    usec_t realtime = now_realtime_usec(), monotonic = now_monotonic_usec();
    int ret = 0;

    // detect if monotonic and realtime have twice the difference
    // in which case we assume the system was just waken from hibernation

    if(last_realtime && last_monotonic && realtime - last_realtime > 2 * (monotonic - last_monotonic))
        ret = 1;

    last_realtime = realtime;
    last_monotonic = monotonic;

    return ret;
}

static void health_main_cleanup(void *ptr) {
    worker_unregister();

    struct netdata_static_thread *static_thread = (struct netdata_static_thread *)ptr;
    static_thread->enabled = NETDATA_MAIN_THREAD_EXITING;
    info("cleaning up...");
    static_thread->enabled = NETDATA_MAIN_THREAD_EXITED;

    log_health("Health thread ended.");
}

static void initialize_health(RRDHOST *host)
{
    if(!host->health.health_enabled ||
        rrdhost_flag_check(host, RRDHOST_FLAG_INITIALIZED_HEALTH) ||
        !service_running(SERVICE_HEALTH))
        return;

    rrdhost_flag_set(host, RRDHOST_FLAG_INITIALIZED_HEALTH);

    log_health("[%s]: Initializing health.", rrdhost_hostname(host));

    host->health.health_default_warn_repeat_every = config_get_duration(CONFIG_SECTION_HEALTH, "default repeat warning", "never");
    host->health.health_default_crit_repeat_every = config_get_duration(CONFIG_SECTION_HEALTH, "default repeat critical", "never");

    host->health_log.next_log_id = 1;
    host->health_log.next_alarm_id = 1;
    host->health_log.max = 1000;
    host->health_log.next_log_id = (uint32_t)now_realtime_sec();
    host->health_log.next_alarm_id = 0;

    long n = config_get_number(CONFIG_SECTION_HEALTH, "in memory max health log entries", host->health_log.max);
    if(n < 10) {
        error("Host '%s': health configuration has invalid max log entries %ld. Using default %u", rrdhost_hostname(host), n, host->health_log.max);
        config_set_number(CONFIG_SECTION_HEALTH, "in memory max health log entries", (long)host->health_log.max);
    }
    else
        host->health_log.max = (unsigned int)n;

    conf_enabled_alarms = simple_pattern_create(config_get(CONFIG_SECTION_HEALTH, "enabled alarms", "*"), NULL,
                                                SIMPLE_PATTERN_EXACT, true);

    netdata_rwlock_init(&host->health_log.alarm_log_rwlock);

    char filename[FILENAME_MAX + 1];

    snprintfz(filename, FILENAME_MAX, "%s/alarm-notify.sh", netdata_configured_primary_plugins_dir);
    host->health.health_default_exec = string_strdupz(config_get(CONFIG_SECTION_HEALTH, "script to execute on alarm", filename));
    host->health.health_default_recipient = string_strdupz("root");

    // TODO: This needs to go to the metadata thread
    // Health should wait before accessing the table (needs to be created by the metadata thread)
    sql_create_health_log_table(host);
    sql_health_alarm_log_load(host);

    // ------------------------------------------------------------------------
    // load health configuration

    health_readdir(host, health_user_config_dir(), health_stock_config_dir(), NULL);

    // link the loaded alarms to their charts
    RRDSET *st;
    rrdset_foreach_reentrant(st, host) {
        if (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED))
            continue;

        rrdcalc_link_matching_alerts_to_rrdset(st);
        rrdcalctemplate_link_matching_templates_to_rrdset(st);
    }
    rrdset_foreach_done(st);

    //Discard alarms with labels that do not apply to host
    rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(host);
}

static void health_sleep(time_t next_run, unsigned int loop __maybe_unused) {
    time_t now = now_realtime_sec();
    if(now < next_run) {
        worker_is_idle();
        debug(D_HEALTH, "Health monitoring iteration no %u done. Next iteration in %d secs", loop, (int) (next_run - now));
        while (now < next_run && service_running(SERVICE_HEALTH)) {
            sleep_usec(USEC_PER_SEC);
            now = now_realtime_sec();
        }
    }
    else {
        debug(D_HEALTH, "Health monitoring iteration no %u done. Next iteration now", loop);
    }
}

static SILENCE_TYPE check_silenced(RRDCALC *rc, const char *host, SILENCERS *silencers) {
    SILENCER *s;
    debug(D_HEALTH, "Checking if alarm was silenced via the command API. Alarm info name:%s context:%s chart:%s host:%s family:%s",
          rrdcalc_name(rc), (rc->rrdset)?rrdset_context(rc->rrdset):"", rrdcalc_chart_name(rc), host, (rc->rrdset)?rrdset_family(rc->rrdset):"");

    for (s = silencers->silencers; s!=NULL; s=s->next){
        if (
                (!s->alarms_pattern || (rc->name && s->alarms_pattern && simple_pattern_matches_string(s->alarms_pattern, rc->name))) &&
                (!s->contexts_pattern || (rc->rrdset && rc->rrdset->context && s->contexts_pattern && simple_pattern_matches_string(s->contexts_pattern, rc->rrdset->context))) &&
                (!s->hosts_pattern || (host && s->hosts_pattern && simple_pattern_matches(s->hosts_pattern, host))) &&
                (!s->charts_pattern || (rc->chart && s->charts_pattern && simple_pattern_matches_string(s->charts_pattern, rc->chart))) &&
                (!s->families_pattern || (rc->rrdset && rc->rrdset->family && s->families_pattern && simple_pattern_matches_string(s->families_pattern, rc->rrdset->family)))
                ) {
            debug(D_HEALTH, "Alarm matches command API silence entry %s:%s:%s:%s:%s", s->alarms,s->charts, s->contexts, s->hosts, s->families);
            if (unlikely(silencers->stype == STYPE_NONE)) {
                debug(D_HEALTH, "Alarm %s matched a silence entry, but no SILENCE or DISABLE command was issued via the command API. The match has no effect.", rrdcalc_name(rc));
            } else {
                debug(D_HEALTH, "Alarm %s via the command API - name:%s context:%s chart:%s host:%s family:%s"
                        , (silencers->stype == STYPE_DISABLE_ALARMS)?"Disabled":"Silenced"
                        , rrdcalc_name(rc)
                        , (rc->rrdset)?rrdset_context(rc->rrdset):""
                        , rrdcalc_chart_name(rc)
                        , host
                        , (rc->rrdset)?rrdset_family(rc->rrdset):""
                        );
            }
            return silencers->stype;
        }
    }
    return STYPE_NONE;
}

/**
 * Update Disabled Silenced
 *
 * Update the variable rrdcalc_flags of the structure RRDCALC according with the values of the host structure
 *
 * @param host structure that contains information about the host monitored.
 * @param rc structure with information about the alarm
 *
 * @return It returns 1 case rrdcalc_flags is DISABLED or 0 otherwise
 */
static int update_disabled_silenced(RRDHOST *host, RRDCALC *rc) {
    uint32_t rrdcalc_flags_old = rc->run_flags;
    // Clear the flags
    rc->run_flags &= ~(RRDCALC_FLAG_DISABLED | RRDCALC_FLAG_SILENCED);
    if (unlikely(silencers->all_alarms)) {
        if (silencers->stype == STYPE_DISABLE_ALARMS) rc->run_flags |= RRDCALC_FLAG_DISABLED;
        else if (silencers->stype == STYPE_SILENCE_NOTIFICATIONS) rc->run_flags |= RRDCALC_FLAG_SILENCED;
    } else {
        SILENCE_TYPE st = check_silenced(rc, rrdhost_hostname(host), silencers);
        if (st == STYPE_DISABLE_ALARMS) rc->run_flags |= RRDCALC_FLAG_DISABLED;
        else if (st == STYPE_SILENCE_NOTIFICATIONS) rc->run_flags |= RRDCALC_FLAG_SILENCED;
    }

    if (rrdcalc_flags_old != rc->run_flags) {
        info("Alarm silencing changed for host '%s' alarm '%s': Disabled %s->%s Silenced %s->%s",
             rrdhost_hostname(host),
             rrdcalc_name(rc),
             (rrdcalc_flags_old & RRDCALC_FLAG_DISABLED)?"true":"false",
             (rc->run_flags & RRDCALC_FLAG_DISABLED)?"true":"false",
             (rrdcalc_flags_old & RRDCALC_FLAG_SILENCED)?"true":"false",
             (rc->run_flags & RRDCALC_FLAG_SILENCED)?"true":"false"
        );
    }
    if (rc->run_flags & RRDCALC_FLAG_DISABLED)
        return 1;
    else
        return 0;
}

static void sql_health_postpone_queue_removed(RRDHOST *host __maybe_unused) {
#ifdef ENABLE_ACLK
    if (netdata_cloud_setting) {
        struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
        if (unlikely(!wc)) {
            return;
        }

        if (wc->alert_queue_removed >= 1) {
            wc->alert_queue_removed+=6;
        }
    }
#endif
}

static void health_execute_delayed_initializations(RRDHOST *host) {
    RRDSET *st;
    bool must_postpone = false;

    if (!rrdhost_flag_check(host, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION)) return;
    rrdhost_flag_clear(host, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);

    rrdset_foreach_reentrant(st, host) {
        if(!rrdset_flag_check(st, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION)) continue;
        rrdset_flag_clear(st, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);

        worker_is_busy(WORKER_HEALTH_JOB_DELAYED_INIT_RRDSET);

        rrdcalc_link_matching_alerts_to_rrdset(st);
        rrdcalctemplate_link_matching_templates_to_rrdset(st);

        RRDDIM *rd;
        rrddim_foreach_read(rd, st) {
            if(!rrddim_flag_check(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION)) continue;
            rrddim_flag_clear(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION);

            worker_is_busy(WORKER_HEALTH_JOB_DELAYED_INIT_RRDDIM);

            RRDCALCTEMPLATE *rt;
            foreach_rrdcalctemplate_read(host, rt) {
                if(!rt->foreach_dimension_pattern)
                    continue;

                if(rrdcalctemplate_check_rrdset_conditions(rt, st, host)) {
                    rrdcalctemplate_check_rrddim_conditions_and_link(rt, st, rd, host);
                }
            }
            foreach_rrdcalctemplate_done(rt);

            if (health_variable_check(health_rrdvars, st, rd))
                rrdvar_store_for_chart(host, st);
        }
        rrddim_foreach_done(rd);
        must_postpone = true;
    }
    rrdset_foreach_done(st);
    if (must_postpone)
        sql_health_postpone_queue_removed(host);
}

/**
 * Health Main
 *
 * The main thread of the health system. In this function all the alarms will be processed.
 *
 * @param ptr is a pointer to the netdata_static_thread structure.
 *
 * @return It always returns NULL
 */

void *health_main(void *ptr) {
    worker_register("HEALTH");
    worker_register_job_name(WORKER_HEALTH_JOB_RRD_LOCK, "rrd lock");
    worker_register_job_name(WORKER_HEALTH_JOB_HOST_LOCK, "host lock");
    worker_register_job_name(WORKER_HEALTH_JOB_DB_QUERY, "db lookup");
    worker_register_job_name(WORKER_HEALTH_JOB_CALC_EVAL, "calc eval");
    worker_register_job_name(WORKER_HEALTH_JOB_WARNING_EVAL, "warning eval");
    worker_register_job_name(WORKER_HEALTH_JOB_CRITICAL_EVAL, "critical eval");
    worker_register_job_name(WORKER_HEALTH_JOB_ALARM_LOG_ENTRY, "alarm log entry");
    worker_register_job_name(WORKER_HEALTH_JOB_ALARM_LOG_PROCESS, "alarm log process");
    worker_register_job_name(WORKER_HEALTH_JOB_DELAYED_INIT_RRDSET, "rrdset init");
    worker_register_job_name(WORKER_HEALTH_JOB_DELAYED_INIT_RRDDIM, "rrddim init");

    netdata_thread_cleanup_push(health_main_cleanup, ptr);

    int min_run_every = (int)config_get_number(CONFIG_SECTION_HEALTH, "run at least every seconds", 10);
    if(min_run_every < 1) min_run_every = 1;

    time_t hibernation_delay  = config_get_number(CONFIG_SECTION_HEALTH, "postpone alarms during hibernation for seconds", 60);

    bool health_running_logged = false;

    rrdcalc_delete_alerts_not_matching_host_labels_from_all_hosts();

    unsigned int loop = 0;

    while(service_running(SERVICE_HEALTH)) {
        loop++;
        debug(D_HEALTH, "Health monitoring iteration no %u started", loop);

        time_t now = now_realtime_sec();
        int runnable = 0, apply_hibernation_delay = 0;
        time_t next_run = now + min_run_every;
        RRDCALC *rc;
        RRDHOST *host;

        if (unlikely(check_if_resumed_from_suspension())) {
            apply_hibernation_delay = 1;

            log_health(
                       "Postponing alarm checks for %"PRId64" seconds, "
                       "because it seems that the system was just resumed from suspension.",
                       (int64_t)hibernation_delay);
        }

        if (unlikely(silencers->all_alarms && silencers->stype == STYPE_DISABLE_ALARMS)) {
            static int logged=0;
            if (!logged) {
                log_health("Skipping health checks, because all alarms are disabled via a %s command.",
                           HEALTH_CMDAPI_CMD_DISABLEALL);
                logged = 1;
            }
        }

        worker_is_busy(WORKER_HEALTH_JOB_RRD_LOCK);
        dfe_start_reentrant(rrdhost_root_index, host) {

            if(unlikely(!service_running(SERVICE_HEALTH)))
                break;

            if (unlikely(!host->health.health_enabled))
                continue;

            if (unlikely(!rrdhost_flag_check(host, RRDHOST_FLAG_INITIALIZED_HEALTH)))
                initialize_health(host);

            health_execute_delayed_initializations(host);

            rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(host);

            if (unlikely(apply_hibernation_delay)) {
                log_health(
                           "[%s]: Postponing health checks for %"PRId64" seconds.",
                           rrdhost_hostname(host),
                           (int64_t)hibernation_delay);

                host->health.health_delay_up_to = now + hibernation_delay;
            }

            if (unlikely(host->health.health_delay_up_to)) {
                if (unlikely(now < host->health.health_delay_up_to)) {
                    continue;
                }

                log_health("[%s]: Resuming health checks after delay.", rrdhost_hostname(host));
                host->health.health_delay_up_to = 0;
            }

            // wait until cleanup of obsolete charts on children is complete
            if (host != localhost) {
                if (unlikely(host->trigger_chart_obsoletion_check == 1)) {
                    log_health("[%s]: Waiting for chart obsoletion check.", rrdhost_hostname(host));
                    continue;
                }
            }

            if (!health_running_logged) {
                log_health("[%s]: Health is running.", rrdhost_hostname(host));
                health_running_logged = true;
            }

            worker_is_busy(WORKER_HEALTH_JOB_HOST_LOCK);

            // the first loop is to lookup values from the db
            foreach_rrdcalc_in_rrdhost_read(host, rc) {

                if(unlikely(!service_running(SERVICE_HEALTH)))
                    break;

                rrdcalc_update_info_using_rrdset_labels(rc);

                if (update_disabled_silenced(host, rc))
                    continue;

                // create an alert removed event if the chart is obsolete and
                // has stopped being collected for 60 seconds
                if (unlikely(rc->rrdset && rc->status != RRDCALC_STATUS_REMOVED &&
                             rrdset_flag_check(rc->rrdset, RRDSET_FLAG_OBSOLETE) &&
                             now > (rc->rrdset->last_collected_time.tv_sec + 60))) {
                    if (!rrdcalc_isrepeating(rc)) {
                        worker_is_busy(WORKER_HEALTH_JOB_ALARM_LOG_ENTRY);
                        time_t now = now_realtime_sec();

                        ALARM_ENTRY *ae = health_create_alarm_entry(
                                                                    host,
                                                                    rc->id,
                                                                    rc->next_event_id++,
                                                                    rc->config_hash_id,
                                                                    now,
                                                                    rc->name,
                                                                    rc->rrdset->id,
                                                                    rc->rrdset->context,
                                                                    rc->rrdset->family,
                                                                    rc->classification,
                                                                    rc->component,
                                                                    rc->type,
                                                                    rc->exec,
                                                                    rc->recipient,
                                                                    now - rc->last_status_change,
                                                                    rc->value,
                                                                    NAN,
                                                                    rc->status,
                                                                    RRDCALC_STATUS_REMOVED,
                                                                    rc->source,
                                                                    rc->units,
                                                                    rc->info,
                                                                    0,
                                                                    rrdcalc_isrepeating(rc)?HEALTH_ENTRY_FLAG_IS_REPEATING:0);

                        if (ae) {
                            health_alarm_log_add_entry(host, ae);
                            rc->old_status = rc->status;
                            rc->status = RRDCALC_STATUS_REMOVED;
                            rc->last_status_change = now;
                            rc->last_updated = now;
                            rc->value = NAN;

#ifdef ENABLE_ACLK
                            if (netdata_cloud_setting)
                                sql_queue_alarm_to_aclk(host, ae, 1);
#endif
                        }
                    }
                }

                if (unlikely(!rrdcalc_isrunnable(rc, now, &next_run))) {
                    if (unlikely(rc->run_flags & RRDCALC_FLAG_RUNNABLE))
                        rc->run_flags &= ~RRDCALC_FLAG_RUNNABLE;
                    continue;
                }

                runnable++;
                rc->old_value = rc->value;
                rc->run_flags |= RRDCALC_FLAG_RUNNABLE;

                // ------------------------------------------------------------
                // if there is database lookup, do it

                if (unlikely(RRDCALC_HAS_DB_LOOKUP(rc))) {
                    worker_is_busy(WORKER_HEALTH_JOB_DB_QUERY);

                    /* time_t old_db_timestamp = rc->db_before; */
                    int value_is_null = 0;

                    int ret = rrdset2value_api_v1(rc->rrdset, NULL, &rc->value, rrdcalc_dimensions(rc), 1,
                                                  rc->after, rc->before, rc->group, NULL,
                                                  0, rc->options,
                                                  &rc->db_after,&rc->db_before,
                                                  NULL, NULL, NULL,
                                                  &value_is_null, NULL, 0, 0,
                                                  QUERY_SOURCE_HEALTH, STORAGE_PRIORITY_LOW);

                    if (unlikely(ret != 200)) {
                        // database lookup failed
                        rc->value = NAN;
                        rc->run_flags |= RRDCALC_FLAG_DB_ERROR;

                        debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': database lookup returned error %d",
                              rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc), ret
                              );
                    } else
                        rc->run_flags &= ~RRDCALC_FLAG_DB_ERROR;

                    if (unlikely(value_is_null)) {
                        // collected value is null
                        rc->value = NAN;
                        rc->run_flags |= RRDCALC_FLAG_DB_NAN;

                        debug(D_HEALTH,
                              "Health on host '%s', alarm '%s.%s': database lookup returned empty value (possibly value is not collected yet)",
                              rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc)
                              );
                    } else
                        rc->run_flags &= ~RRDCALC_FLAG_DB_NAN;

                    debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': database lookup gave value " NETDATA_DOUBLE_FORMAT,
                          rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc), rc->value
                          );
                }

                // ------------------------------------------------------------
                // if there is calculation expression, run it

                if (unlikely(rc->calculation)) {
                    worker_is_busy(WORKER_HEALTH_JOB_CALC_EVAL);

                    if (unlikely(!expression_evaluate(rc->calculation))) {
                        // calculation failed
                        rc->value = NAN;
                        rc->run_flags |= RRDCALC_FLAG_CALC_ERROR;

                        debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': expression '%s' failed: %s",
                              rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc),
                              rc->calculation->parsed_as, buffer_tostring(rc->calculation->error_msg)
                              );
                    } else {
                        rc->run_flags &= ~RRDCALC_FLAG_CALC_ERROR;

                        debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': expression '%s' gave value "
                              NETDATA_DOUBLE_FORMAT
                              ": %s (source: %s)", rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc),
                              rc->calculation->parsed_as, rc->calculation->result,
                              buffer_tostring(rc->calculation->error_msg), rrdcalc_source(rc)
                              );

                        rc->value = rc->calculation->result;
                    }
                }
            }
            foreach_rrdcalc_in_rrdhost_done(rc);

            if (unlikely(runnable && service_running(SERVICE_HEALTH))) {
                foreach_rrdcalc_in_rrdhost_read(host, rc) {
                    if(unlikely(!service_running(SERVICE_HEALTH)))
                        break;

                    if (unlikely(!(rc->run_flags & RRDCALC_FLAG_RUNNABLE)))
                        continue;

                    if (rc->run_flags & RRDCALC_FLAG_DISABLED) {
                        continue;
                    }
                    RRDCALC_STATUS warning_status = RRDCALC_STATUS_UNDEFINED;
                    RRDCALC_STATUS critical_status = RRDCALC_STATUS_UNDEFINED;

                    // --------------------------------------------------------
                    // check the warning expression

                    if (likely(rc->warning)) {
                        worker_is_busy(WORKER_HEALTH_JOB_WARNING_EVAL);

                        if (unlikely(!expression_evaluate(rc->warning))) {
                            // calculation failed
                            rc->run_flags |= RRDCALC_FLAG_WARN_ERROR;

                            debug(D_HEALTH,
                                  "Health on host '%s', alarm '%s.%s': warning expression failed with error: %s",
                                  rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc),
                                  buffer_tostring(rc->warning->error_msg)
                                  );
                        } else {
                            rc->run_flags &= ~RRDCALC_FLAG_WARN_ERROR;
                            debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': warning expression gave value "
                                  NETDATA_DOUBLE_FORMAT
                                  ": %s (source: %s)", rrdhost_hostname(host), rrdcalc_chart_name(rc),
                                  rrdcalc_name(rc), rc->warning->result, buffer_tostring(rc->warning->error_msg), rrdcalc_source(rc)
                                  );
                            warning_status = rrdcalc_value2status(rc->warning->result);
                        }
                    }

                    // --------------------------------------------------------
                    // check the critical expression

                    if (likely(rc->critical)) {
                        worker_is_busy(WORKER_HEALTH_JOB_CRITICAL_EVAL);

                        if (unlikely(!expression_evaluate(rc->critical))) {
                            // calculation failed
                            rc->run_flags |= RRDCALC_FLAG_CRIT_ERROR;

                            debug(D_HEALTH,
                                  "Health on host '%s', alarm '%s.%s': critical expression failed with error: %s",
                                  rrdhost_hostname(host), rrdcalc_chart_name(rc), rrdcalc_name(rc),
                                  buffer_tostring(rc->critical->error_msg)
                                  );
                        } else {
                            rc->run_flags &= ~RRDCALC_FLAG_CRIT_ERROR;
                            debug(D_HEALTH, "Health on host '%s', alarm '%s.%s': critical expression gave value "
                                  NETDATA_DOUBLE_FORMAT
                                  ": %s (source: %s)", rrdhost_hostname(host), rrdcalc_chart_name(rc),
                                  rrdcalc_name(rc), rc->critical->result, buffer_tostring(rc->critical->error_msg),
                                  rrdcalc_source(rc)
                                  );
                            critical_status = rrdcalc_value2status(rc->critical->result);
                        }
                    }

                    // --------------------------------------------------------
                    // decide the final alarm status

                    RRDCALC_STATUS status = RRDCALC_STATUS_UNDEFINED;

                    switch (warning_status) {
                    case RRDCALC_STATUS_CLEAR:
                        status = RRDCALC_STATUS_CLEAR;
                        break;

                    case RRDCALC_STATUS_RAISED:
                        status = RRDCALC_STATUS_WARNING;
                        break;

                    default:
                        break;
                    }

                    switch (critical_status) {
                    case RRDCALC_STATUS_CLEAR:
                        if (status == RRDCALC_STATUS_UNDEFINED)
                            status = RRDCALC_STATUS_CLEAR;
                        break;

                    case RRDCALC_STATUS_RAISED:
                        status = RRDCALC_STATUS_CRITICAL;
                        break;

                    default:
                        break;
                    }

                    // --------------------------------------------------------
                    // check if the new status and the old differ

                    if (status != rc->status) {
                        worker_is_busy(WORKER_HEALTH_JOB_ALARM_LOG_ENTRY);
                        int delay = 0;

                        // apply trigger hysteresis

                        if (now > rc->delay_up_to_timestamp) {
                            rc->delay_up_current = rc->delay_up_duration;
                            rc->delay_down_current = rc->delay_down_duration;
                            rc->delay_last = 0;
                            rc->delay_up_to_timestamp = 0;
                        } else {
                            rc->delay_up_current = (int) (rc->delay_up_current * rc->delay_multiplier);
                            if (rc->delay_up_current > rc->delay_max_duration)
                                rc->delay_up_current = rc->delay_max_duration;

                            rc->delay_down_current = (int) (rc->delay_down_current * rc->delay_multiplier);
                            if (rc->delay_down_current > rc->delay_max_duration)
                                rc->delay_down_current = rc->delay_max_duration;
                        }

                        if (status > rc->status)
                            delay = rc->delay_up_current;
                        else
                            delay = rc->delay_down_current;

                        // COMMENTED: because we do need to send raising alarms
                        // if(now + delay < rc->delay_up_to_timestamp)
                        //      delay = (int)(rc->delay_up_to_timestamp - now);

                        rc->delay_last = delay;
                        rc->delay_up_to_timestamp = now + delay;

                        ALARM_ENTRY *ae = health_create_alarm_entry(
                                                                    host,
                                                                    rc->id,
                                                                    rc->next_event_id++,
                                                                    rc->config_hash_id,
                                                                    now,
                                                                    rc->name,
                                                                    rc->rrdset->id,
                                                                    rc->rrdset->context,
                                                                    rc->rrdset->family,
                                                                    rc->classification,
                                                                    rc->component,
                                                                    rc->type,
                                                                    rc->exec,
                                                                    rc->recipient,
                                                                    now - rc->last_status_change,
                                                                    rc->old_value,
                                                                    rc->value,
                                                                    rc->status,
                                                                    status,
                                                                    rc->source,
                                                                    rc->units,
                                                                    rc->info,
                                                                    rc->delay_last,
                                                                    (
                                                                     ((rc->options & RRDCALC_OPTION_NO_CLEAR_NOTIFICATION)? HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION : 0) |
                                                                     ((rc->run_flags & RRDCALC_FLAG_SILENCED)? HEALTH_ENTRY_FLAG_SILENCED : 0) |
                                                                     (rrdcalc_isrepeating(rc)?HEALTH_ENTRY_FLAG_IS_REPEATING:0)
                                                                     )
                                                                    );

                        health_alarm_log_add_entry(host, ae);

                        log_health("[%s]: Alert event for [%s.%s], value [%s], status [%s].", rrdhost_hostname(host), ae_chart_name(ae), ae_name(ae), ae_new_value_string(ae), rrdcalc_status2string(ae->new_status));

                        rc->last_status_change = now;
                        rc->old_status = rc->status;
                        rc->status = status;
                    }

                    rc->last_updated = now;
                    rc->next_update = now + rc->update_every;

                    if (next_run > rc->next_update)
                        next_run = rc->next_update;
                }
                foreach_rrdcalc_in_rrdhost_done(rc);

                // process repeating alarms
                foreach_rrdcalc_in_rrdhost_read(host, rc) {
                    if(unlikely(!service_running(SERVICE_HEALTH)))
                        break;

                    int repeat_every = 0;
                    if(unlikely(rrdcalc_isrepeating(rc) && rc->delay_up_to_timestamp <= now)) {
                        if(unlikely(rc->status == RRDCALC_STATUS_WARNING)) {
                            rc->run_flags &= ~RRDCALC_FLAG_RUN_ONCE;
                            repeat_every = rc->warn_repeat_every;
                        } else if(unlikely(rc->status == RRDCALC_STATUS_CRITICAL)) {
                            rc->run_flags &= ~RRDCALC_FLAG_RUN_ONCE;
                            repeat_every = rc->crit_repeat_every;
                        } else if(unlikely(rc->status == RRDCALC_STATUS_CLEAR)) {
                            if(!(rc->run_flags & RRDCALC_FLAG_RUN_ONCE)) {
                                if(rc->old_status == RRDCALC_STATUS_CRITICAL) {
                                    repeat_every = 1;
                                } else if (rc->old_status == RRDCALC_STATUS_WARNING) {
                                    repeat_every = 1;
                                }
                            }
                        }
                    } else {
                        continue;
                    }

                    if(unlikely(repeat_every > 0 && (rc->last_repeat + repeat_every) <= now)) {
                        worker_is_busy(WORKER_HEALTH_JOB_ALARM_LOG_ENTRY);
                        rc->last_repeat = now;
                        if (likely(rc->times_repeat < UINT32_MAX)) rc->times_repeat++;

                        ALARM_ENTRY *ae = health_create_alarm_entry(
                                                                    host,
                                                                    rc->id,
                                                                    rc->next_event_id++,
                                                                    rc->config_hash_id,
                                                                    now,
                                                                    rc->name,
                                                                    rc->rrdset->id,
                                                                    rc->rrdset->context,
                                                                    rc->rrdset->family,
                                                                    rc->classification,
                                                                    rc->component,
                                                                    rc->type,
                                                                    rc->exec,
                                                                    rc->recipient,
                                                                    now - rc->last_status_change,
                                                                    rc->old_value,
                                                                    rc->value,
                                                                    rc->old_status,
                                                                    rc->status,
                                                                    rc->source,
                                                                    rc->units,
                                                                    rc->info,
                                                                    rc->delay_last,
                                                                    (
                                                                     ((rc->options & RRDCALC_OPTION_NO_CLEAR_NOTIFICATION)? HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION : 0) |
                                                                     ((rc->run_flags & RRDCALC_FLAG_SILENCED)? HEALTH_ENTRY_FLAG_SILENCED : 0) |
                                                                     (rrdcalc_isrepeating(rc)?HEALTH_ENTRY_FLAG_IS_REPEATING:0)
                                                                     )
                                                                    );

                        ae->last_repeat = rc->last_repeat;
                        if (!(rc->run_flags & RRDCALC_FLAG_RUN_ONCE) && rc->status == RRDCALC_STATUS_CLEAR) {
                            ae->flags |= HEALTH_ENTRY_RUN_ONCE;
                        }
                        rc->run_flags |= RRDCALC_FLAG_RUN_ONCE;
                        health_process_notifications(host, ae);
                        debug(D_HEALTH, "Notification sent for the repeating alarm %u.", ae->alarm_id);
                        health_alarm_wait_for_execution(ae);
                        health_alarm_log_free_one_nochecks_nounlink(ae);
                    }
                }
                foreach_rrdcalc_in_rrdhost_done(rc);
            }

            if (unlikely(!service_running(SERVICE_HEALTH)))
                break;

            // execute notifications
            // and cleanup
            worker_is_busy(WORKER_HEALTH_JOB_ALARM_LOG_PROCESS);
            health_alarm_log_process(host);

            if (unlikely(!service_running(SERVICE_HEALTH))) {
                // wait for all notifications to finish before allowing health to be cleaned up
                ALARM_ENTRY *ae;
                while (NULL != (ae = alarm_notifications_in_progress.head)) {
                    if(unlikely(!service_running(SERVICE_HEALTH)))
                        break;

                    health_alarm_wait_for_execution(ae);
                }
                break;
            }
#ifdef ENABLE_ACLK
            if (netdata_cloud_setting) {
                struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
                if (unlikely(!wc)) {
                    continue;
                }

                if (wc->alert_queue_removed == 1) {
                    sql_queue_removed_alerts_to_aclk(host);
                } else if (wc->alert_queue_removed > 1) {
                    wc->alert_queue_removed--;
                }

                if (wc->alert_checkpoint_req == 1) {
                    aclk_push_alarm_checkpoint(host);
                } else if (wc->alert_checkpoint_req > 1) {
                    wc->alert_checkpoint_req--;
                }
            }
#endif
        }
        dfe_done(host);

        // wait for all notifications to finish before allowing health to be cleaned up
        ALARM_ENTRY *ae;
        while (NULL != (ae = alarm_notifications_in_progress.head)) {
            if(unlikely(!service_running(SERVICE_HEALTH)))
                break;

            health_alarm_wait_for_execution(ae);
        }

        if(unlikely(!service_running(SERVICE_HEALTH)))
            break;

        health_sleep(next_run, loop);

    } // forever

    netdata_thread_cleanup_pop(1);
    return NULL;
}

void health_add_host_labels(void) {
    DICTIONARY *labels = localhost->rrdlabels;

    // The source should be CONF, but when it is set, these labels are exported by default ('send configured labels' in exporting.conf).
    // Their export seems to break exporting to Graphite, see https://github.com/netdata/netdata/issues/14084.

    int is_ephemeral = appconfig_get_boolean(&netdata_config, CONFIG_SECTION_HEALTH, "is ephemeral", CONFIG_BOOLEAN_NO);
    rrdlabels_add(labels, "_is_ephemeral", is_ephemeral ? "true" : "false", RRDLABEL_SRC_AUTO);

    int has_unstable_connection = appconfig_get_boolean(&netdata_config, CONFIG_SECTION_HEALTH, "has unstable connection", CONFIG_BOOLEAN_NO);
    rrdlabels_add(labels, "_has_unstable_connection", has_unstable_connection ? "true" : "false", RRDLABEL_SRC_AUTO);
}