Latest commit 19ab7a8 Jan 13, 2017 @ktsaou ktsaou added PR number

README.md

netdata plugins

Any program that can print a few values to its standard output can become a netdata plugin.

There are 5 lines netdata parses. lines starting with:

  • CHART - create a new chart
  • DIMENSION - add a dimension to the chart just created
  • BEGIN - initialize data collection for a chart
  • SET - set the value of a dimension for the initialized chart
  • END - complete data collection for the initialized chart

a single program can produce any number of charts with any number of dimensions each.

charts can also be added any time (not just the beginning).

command line parameters

The plugin should accept just one parameter: the number of seconds it is expected to update the values for its charts. The value passed by netdata to the plugin is controlled via its configuration file (so there is not need for the plugin to handle this configuration option).

The script can overwrite the update frequency. For example, the server may request per second updates, but the script may overwrite this to one update every 5 seconds.

environment variables

There are a few environment variables that are set by netdata and are available for the plugin to use.

variable description
NETDATA_CONFIG_DIR The directory where all netdata related configuration should be stored. If the plugin requires custom configuration, this is the place to save it.
NETDATA_PLUGINS_DIR The directory where all netdata plugins are stored.
NETDATA_WEB_DIR The directory where the web files of netdata are saved.
NETDATA_CACHE_DIR The directory where the cache files of netdata are stored. Use this directory if the plugin requires a place to store data. A new directory should be created for the plugin for this purpose, inside this directory.
NETDATA_LOG_DIR The directory where the log files are stored. By default the stderr output of the plugin will be saved in the error.log file of netdata.
NETDATA_HOST_PREFIX This is used in environments where system directories like /sys and /proc have to be accessed at a different path.
NETDATA_DEBUG_FLAGS This is number (probably in hex starting with 0x), that enables certain netdata debugging features.
NETDATA_UPDATE_EVERY The minimum number of seconds between chart refreshes. This is like the internal clock of netdata (it is user configurable, defaulting to 1). There is no meaning for a plugin to update its values more frequently than this number of seconds.

the output of the plugin

The plugin should output instructions for netdata to its output (stdout).

CHART

CHART defines a new chart.

the template is:

CHART type.id name title units [family [category [charttype [priority [update_every]]]]]

where:

  • type.id

    uniquely identifies the chart, this is what will be needed to add values to the chart

  • name

    is the name that will be presented to the used for this chart

  • title

    the text above the chart

  • units

    the label of the vertical axis of the chart, all dimensions added to a chart should have the same units of measurement

  • family

    is used to group charts together (for example all eth0 charts should say: eth0), if empty or missing, the id part of type.id will be used

  • category

    the section under which the chart will appear (for example mem.ram should appear in the 'system' section), the special word 'none' means: do not show this chart on the home page, if empty or missing, the type part of type.id will be used

  • charttype

    one of line, area or stacked, if empty or missing, the line will be used

  • priority

    is the relative priority of the charts as rendered on the web page, lower numbers make the charts appear before the ones with higher numbers, if empty or missing, 1000 will be used

  • update_every

    overwrite the update frequency set by the server, if empty or missing, the user configured value will be used

DIMENSION

DIMENSION defines a new dimension for the chart

the template is:

DIMENSION id [name [algorithm [multiplier [divisor [hidden]]]]]

where:

  • id

    the id of this dimension (it is a text value, not numeric), this will be needed later to add values to the dimension

  • name

    the name of the dimension as it will appear at the legend of the chart, if empty or missing the id will be used

  • algorithm

    one of:

    • absolute

      the value is to drawn as-is (interpolated to second boundary), if algorithm is empty, invalid or missing, absolute is used

    • incremental

      the value increases over time, the difference from the last value is presented in the chart, the server interpolates the value and calculates a per second figure

    • percentage-of-absolute-row

      the % of this value compared to the total of all dimensions

    • percentage-of-incremental-row

      the % of this value compared to the incremental total of all dimensions

  • multiplier

    an integer value to multiply the collected value, if empty or missing, 1 is used

  • divisor

    an integer value to divide the collected value, if empty or missing, 1 is used

  • hidden

    giving the keyword hidden will make this dimension hidden, it will take part in the calculations but will not be presented in the chart

data collection

data collection is defined as a series of BEGIN -> SET -> END lines

BEGIN type.id [microseconds]

  • type.id

    is the unique identification of the chart (as given in CHART)

  • microseconds

    is the number of microseconds since the last update of the chart, it is optional.

    Under heavy system load, the system may have some latency transfering data from the plugins to netdata via the pipe. This number improves accuracy significantly, since the plugin is able to calculate the duration between its iterations better than netdata.

    The first time the plugin is started, no microseconds should be given to netdata.

SET id = value

  • id

    is the unique identification of the dimension (of the chart just began)

  • value

    is the collected value

END

END does not take any parameters, it commits the collected values to the chart.

More SET lines may appear to update all the dimensions of the chart. All of them in one BEGIN -> END block.

All SET lines within a single BEGIN -> END block have to refer to the same chart.

If more charts need to be updated, each chart should have its own BEGIN -> SET -> END block.

If, for any reason, a plugin has issued a BEGIN but wants to cancel it, it can issue a FLUSH. The FLUSH command will instruct netdata to ignore the last BEGIN command.

If a plugin does not behave properly (outputs invalid lines, or does not follow these guidelines), will be disabled by netdata.

collected values

netdata will collect any signed value in the 64bit range: -9.223.372.036.854.775.808 to +9.223.372.036.854.775.807

Internally, all calculations are made using 128 bit double precision and are stored in 30 bits as floating point.

If a value is not collected, leave it empty, like this:

SET id =

or do not output the line at all.