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# Tomcat


<img src="https://netdata.cloud/img/tomcat.svg" width="150"/>


Plugin: go.d.plugin
Module: tomcat

<img src="https://img.shields.io/badge/maintained%20by-Netdata-%2300ab44" />

## Overview

This collector monitors Tomcat metrics about bandwidth, processing time, threads and more.


It parses the information provided by the [Server Status](https://tomcat.apache.org/tomcat-10.0-doc/manager-howto.html#Server_Status) HTTP endpoint.


This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

By default, this Tomcat collector cannot access the server's status page. To enable data collection, you will need to configure access credentials with appropriate permissions.


### Default Behavior

#### Auto-Detection

If the Netdata Agent and Tomcat are on the same host, the collector will attempt to connect to the Tomcat server's status page at `http://localhost:8080/manager/status?XML=true`.


#### Limits

The default configuration for this integration does not impose any limits on data collection.

#### Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.


## Metrics

Metrics grouped by *scope*.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.



### Per Tomcat instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| tomcat.jvm_memory_usage | free, used | bytes |

### Per jvm memory pool

These metrics refer to the JVM memory pool.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| mempool_name | Memory Pool name. |
| mempool_type | Memory Pool type. |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| tomcat.jvm_mem_pool_memory_usage | commited, used, max | bytes |

### Per connector

These metrics refer to the connector.

Labels:

| Label      | Description     |
|:-----------|:----------------|
| connector_name | Connector name. |

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| tomcat.connector_requests | requests | requests/s |
| tomcat.connector_bandwidth | received, sent | bytes/s |
| tomcat.connector_requests_processing_time | processing_time | milliseconds |
| tomcat.connector_errors | errors | errors/s |
| tomcat.connector_request_threads | idle, busy | threads |



## Alerts

There are no alerts configured by default for this integration.


## Setup

### Prerequisites

#### Access to Tomcat Status Endpoint

The Netdata Agent needs read-only access to its status endpoint to collect data from the Tomcat server.

You can achieve this by creating a dedicated user named `netdata` with read-only permissions specifically for accessing the [Server Status](https://tomcat.apache.org/tomcat-10.0-doc/manager-howto.html#Server_Status) endpoint.

Once you've created the `netdata` user, you'll need to configure the username and password in the collector configuration file.



### Configuration

#### File

The configuration file name for this integration is `go.d/tomcat.conf`.


You can edit the configuration file using the [`edit-config`](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#edit-a-configuration-file-using-edit-config) script from the
Netdata [config directory](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#the-netdata-config-directory).

```bash
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/tomcat.conf
```
#### Options

The following options can be defined globally: update_every, autodetection_retry.


<details open><summary>Config options</summary>

| Name | Description | Default | Required |
|:----|:-----------|:-------|:--------:|
| update_every | Data collection frequency. | 1 | no |
| autodetection_retry | Recheck interval in seconds. Zero means no recheck will be scheduled. | 0 | no |
| url | Server URL. | http://127.0.0.1:8080 | yes |
| timeout | HTTP request timeout. | 1 | no |
| username | Username for basic HTTP authentication. |  | no |
| password | Password for basic HTTP authentication. |  | no |
| proxy_url | Proxy URL. |  | no |
| proxy_username | Username for proxy basic HTTP authentication. |  | no |
| proxy_password | Password for proxy basic HTTP authentication. |  | no |
| method | HTTP request method. | POST | no |
| body | HTTP request body. |  | no |
| headers | HTTP request headers. |  | no |
| not_follow_redirects | Redirect handling policy. Controls whether the client follows redirects. | no | no |
| tls_skip_verify | Server certificate chain and hostname validation policy. Controls whether the client performs this check. | no | no |
| tls_ca | Certification authority that the client uses when verifying the server's certificates. |  | no |
| tls_cert | Client TLS certificate. |  | no |
| tls_key | Client TLS key. |  | no |

</details>

#### Examples

##### Basic

A basic example configuration.

```yaml
jobs:
  - name: local
    url: http://127.0.0.1:8080
    username: John
    password: Doe

```
##### Multi-instance

> **Note**: When you define multiple jobs, their names must be unique.

Collecting metrics from local and remote instances.


<details open><summary>Config</summary>

```yaml
jobs:
  - name: local
    url: http://127.0.0.1:8080
    username: admin1
    password: hackme1

  - name: remote
    url: http://192.0.2.1:8080
    username: admin2
    password: hackme2

```
</details>



## Troubleshooting

### Debug Mode

**Important**: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the `tomcat` collector, run the `go.d.plugin` with the debug option enabled. The output
should give you clues as to why the collector isn't working.

- Navigate to the `plugins.d` directory, usually at `/usr/libexec/netdata/plugins.d/`. If that's not the case on
  your system, open `netdata.conf` and look for the `plugins` setting under `[directories]`.

  ```bash
  cd /usr/libexec/netdata/plugins.d/
  ```

- Switch to the `netdata` user.

  ```bash
  sudo -u netdata -s
  ```

- Run the `go.d.plugin` to debug the collector:

  ```bash
  ./go.d.plugin -d -m tomcat
  ```

### Getting Logs

If you're encountering problems with the `tomcat` collector, follow these steps to retrieve logs and identify potential issues:

- **Run the command** specific to your system (systemd, non-systemd, or Docker container).
- **Examine the output** for any warnings or error messages that might indicate issues.  These messages should provide clues about the root cause of the problem.

#### System with systemd

Use the following command to view logs generated since the last Netdata service restart:

```bash
journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep tomcat
```

#### System without systemd

Locate the collector log file, typically at `/var/log/netdata/collector.log`, and use `grep` to filter for collector's name:

```bash
grep tomcat /var/log/netdata/collector.log
```

**Note**: This method shows logs from all restarts. Focus on the **latest entries** for troubleshooting current issues.

#### Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

```bash
docker logs netdata 2>&1 | grep tomcat
```


