netdata/collectors/charts.d.plugin/example/example.chart.sh

# shellcheck shell=bash
# no need for shebang - this file is loaded from charts.d.plugin
# SPDX-License-Identifier: GPL-3.0-or-later

# netdata
# real-time performance and health monitoring, done right!
# (C) 2016 Costa Tsaousis <costa@tsaousis.gr>
#

# if this chart is called X.chart.sh, then all functions and global variables
# must start with X_

# _update_every is a special variable - it holds the number of seconds
# between the calls of the _update() function
example_update_every=

# the priority is used to sort the charts on the dashboard
# 1 = the first chart
example_priority=150000

# to enable this chart, you have to set this to 12345
# (just a demonstration for something that needs to be checked)
example_magic_number=

# global variables to store our collected data
# remember: they need to start with the module name example_
example_value1=
example_value2=
example_value3=
example_value4=
example_last=0
example_count=0

example_get() {
  # do all the work to collect / calculate the values
  # for each dimension
  #
  # Remember:
  # 1. KEEP IT SIMPLE AND SHORT
  # 2. AVOID FORKS (avoid piping commands)
  # 3. AVOID CALLING TOO MANY EXTERNAL PROGRAMS
  # 4. USE LOCAL VARIABLES (global variables may overlap with other modules)

  example_value1=$RANDOM
  example_value2=$RANDOM
  example_value3=$RANDOM
  example_value4=$((8192 + (RANDOM * 16383 / 32767)))

  if [ $example_count -gt 0 ]; then
    example_count=$((example_count - 1))

    [ $example_last -gt 16383 ] && example_value4=$((example_last + (RANDOM * ((32767 - example_last) / 2) / 32767)))
    [ $example_last -le 16383 ] && example_value4=$((example_last - (RANDOM * (example_last / 2) / 32767)))
  else
    example_count=$((1 + (RANDOM * 5 / 32767)))

    if [ $example_last -gt 16383 ] && [ $example_value4 -gt 16383 ]; then
      example_value4=$((example_value4 - 16383))
    fi
    if [ $example_last -le 16383 ] && [ $example_value4 -lt 16383 ]; then
      example_value4=$((example_value4 + 16383))
    fi
  fi
  example_last=$example_value4

  # this should return:
  #  - 0 to send the data to netdata
  #  - 1 to report a failure to collect the data

  return 0
}

# _check is called once, to find out if this chart should be enabled or not
example_check() {
  # this should return:
  #  - 0 to enable the chart
  #  - 1 to disable the chart

  # check something
  [ "${example_magic_number}" != "12345" ] && error "manual configuration required: you have to set example_magic_number=$example_magic_number in example.conf to start example chart." && return 1

  # check that we can collect data
  example_get || return 1

  return 0
}

# _create is called once, to create the charts
example_create() {
  # create the chart with 3 dimensions
  cat << EOF
CHART example.random '' "Random Numbers Stacked Chart" "% of random numbers" random random stacked $((example_priority)) $example_update_every '' '' 'example'
DIMENSION random1 '' percentage-of-absolute-row 1 1
DIMENSION random2 '' percentage-of-absolute-row 1 1
DIMENSION random3 '' percentage-of-absolute-row 1 1
CHART example.random2 '' "A random number" "random number" random random area $((example_priority + 1)) $example_update_every '' '' 'example'
DIMENSION random '' absolute 1 1
EOF

  return 0
}

# _update is called continuously, to collect the values
example_update() {
  # the first argument to this function is the microseconds since last update
  # pass this parameter to the BEGIN statement (see below).

  example_get || return 1

  # write the result of the work.
  cat << VALUESEOF
BEGIN example.random $1
SET random1 = $example_value1
SET random2 = $example_value2
SET random3 = $example_value3
END
BEGIN example.random2 $1
SET random = $example_value4
END
VALUESEOF

  return 0
}