chart

Core API

This module available in Core API

Module chart allows to create an image with a chart. After you can upload an image to remote storage and attach to an alert.

Usage:

script.lua

local chart = require('chart')

Methods

render

render('<CHART_TITLE>', <CHART_OPTIONS>) binaryImageData, error

Render image and return it as binary data

If an error occurred, it will be returned as second value

Chart Options

A structure <CHART_OPTIONS> describe data for build a chart

{
    series = { <CHART_SERIES>, <CHART_SERIES>, ... } 
}

Series is lines on a chart

Series

{
    color = '<COLOR>',
    line_color = '<COLOR>',
    point_color = '<COLOR>',
    data = { <POINT_VALUE>, <POINT_VALUE>, ... }
}

color, line_color, point_color allows define a common color, a line color or a point color

If defined only color - it will be applying to lines and points Default color is black

data contains data for every points

One point describe as:

{
    timestamp = <FLOAT>
    value = <FLOAT>
}

Color

color (color_line, color_point) may have:

One of these values - blue - red - black - green - yellow

String #XXXXXX for define a color in format RGB or #XXXXXXXX for define a color in format RGBA

An example:

color = 'blue'
color = '#00FF00'
color = '#ABCD12FA'

Examples

Manually define a chart data:

script.lua

local chartOptions = {
    ['series'] = {
        {
            ['color'] = '#456789',
            ["data"] = {
                { ['timestamp'] = 12345646554, ['value'] = 95 },
                { ['timestamp'] = 12345646555, ['value'] = 94 },
                { ['timestamp'] = 12345646556, ['value'] = 97 },
                { ['timestamp'] = 12345646557, ['value'] = 93 }
            }
        },
        {
            ['color'] = 'red',
            ["data"] = {
                { ['timestamp'] = 12345646554, ['value'] = 85 },
                { ['timestamp'] = 12345646555, ['value'] = 84 },
                { ['timestamp'] = 12345646556, ['value'] = 87 },
                { ['timestamp'] = 12345646557, ['value'] = 83 }
            }
        }
    }
}

local img, err = chart.render('My Chart', chartOptions)

-- 'img' will be contains an image binary data  

Result image

Obtain a data from Prometheus (Usage metrics from NodeExporter)

script.lua

local rangeOptions = {
    ['start'] = r - 86400,
    ['end'] = r,
    ['step'] = '3600'
}

res1 = prom.range('rate(sum(node_cpu_seconds_total{mode!="idle",node="32"}[5m])) / rate(sum(node_cpu_seconds_total{node="32"}[5m]))', rangeOptions)
res2 = prom.range('rate(sum(node_cpu_seconds_total{mode!="idle",node="43"}[5m])) / rate(sum(node_cpu_seconds_total{node="43"}[5m]))', rangeOptions)

local chartOptions = {
    ['series'] = {
        {
            ['color'] = '#456789',
            ["data"] = res1[1].values,
        },
        {
            ['color'] = 'red',
            ['line_color'] = 'blue',
            ["data"] = res2[1].values,
        }
    }
}


local img, err = chart.render('CPU', chartOptions)

-- 'img' will be contains an image binary data  

Result image

Send image

You can store received image to the upload storage and then use image URL.

For telegram channel you can send raw image data without upload to the storage