check_rest_addon

#!/usr/bin/lua

-- Copyright Julien Thomas < julthomas @ free.fr >
-- Copyright Zenetys < jthomas @ zenetys.com >
-- Author: Julien Thomas
-- Licence: MIT

local lc = require 'libcheck'
local lp = require 'libperfdata'
local lu = require 'libutil'
ZCurl = require 'libzcurl'
require 'print_r'

local ctx = {
    perfdata = {},
    default_parameter = {},
    output_options = {},
}

local env = setmetatable(
    { ctx = ctx, lc = lc, lp = lp, lu = lu, ZCurl = ZCurl },
    { __index = _ENV })
local addon_code = {}

function load_addon(_, value)
    if lc.lfs.attributes(value, 'mode') ~= 'file' then
        if lc.lfs.attributes(lc.progdir..'/'..value, 'mode') == 'file' then
            value = lc.progdir..'/'..value
        else
            lc.die_unkn('Addon not found: '..value)
        end
    end

    lc.debug('load addon: '..value)
    local code, err = loadfile(value, nil, env)
    if not code then
        lc.die_unkn('Failed to load addon: '..err)
    end
    local success, err = pcall(code, 'init')
    if not success then
        lc.die_unkn('Failed to run addon init: '..err)
    end
    lc.optsdef.rebuild()
    table.insert(addon_code, { name = lc.basename(value), code = code })
    return value
end

function load_addon_array(_, value)
    for i in (value..','):gmatch('([^,]*),') do
        load_addon(_, i)
    end
    return value
end

lc.checkname = 'REST'
lc.shortdescr = 'Generic Nagios plugin to query an HTTP JSON REST API'
lc.progtype = 'rest'

lc.opts = {
    parameter = {},
}

lc.optsdef = {
    { short = 'U', long = 'url', help = 'Request URL' },
    { short = 'B', long = 'baseurl', help = 'Default base URL' },
    { short = 'r', long = 'header', call = lc.setter_opt_array, help = 'Request header(s)' },
    { short = 'n', long = 'username', help = 'Authentication username' },
    { short = 'p', long = 'password', help = 'Authentication password' },
    { short = 'd', long = 'post-data', help = 'Request data to POST, otherwise GET' },
    { short = 'X', long = 'method', help = 'Force request method, eg: GET when using --post-data' },
    { short = 'L', long = 'follow', call = lc.setter_opt_boolean, help = 'Follow location' },
    { short = 's', long = 'parameter', call = lc.setter_opt_kv, help = 'Replace ${key} by value in --post-data, format: key=value' },
    { short = 'l', long = 'label', call = lc.setter_opt_array, help = 'Metric(s) name, path[:label]' },
    { short = 'a', long = 'addon', help = 'Custom addon script', call = load_addon_array },
    { short = 'w', long = 'warning', call = lc.setter_opt_array, help = 'Metric(s) warning' },
    { short = 'c', long = 'critical', call = lc.setter_opt_array, help = 'Metric(s) critical' },
    { short = 'u', long = 'uom', call = lc.setter_opt_array, help = 'Metric(s) uom' },
    { short = 'm', long = 'min', call = lc.setter_opt_array, help = 'Metric(s) min' },
    { short = 'M', long = 'max', call = lc.setter_opt_array, help = 'Metric(s) max' },
    { short = 'x', long = 'null-value', call = lc.setter_opt_array, help = 'Metric(s) null value' },
    { short = 't', long = 'timeout', call = lc.setter_opt_number, help = 'cURL timeout in seconds' },
    { short = 'R', long = 'netrc', call = lc.setter_opt_iboolean, help = 'Enable ~/.netrc' },
    { short = 'A', long = 'raw', call = lc.setter_opt_boolean, help = 'Raw data, do not decode JSON' },
    { short = 'j', long = 'cookies', call = lc.setter_opt_boolean, help = 'Store and reuse cookies' },
    { short = 'pt', long = 'perfdata-time', call = lc.setter_opt_number, help = 'Add curl time perfdata (0: never, 1: always, 2: auto)' },
    { short = 'N', long = 'check-name', call = function (o,v) lc.checkname = v; return v end, help = 'Set output prefix' },
}

lc.init_opts()

-- defaults
if not lc.opts.parameter then lc.opts.parameter = {} end
if not lc.opts.label then lc.opts.label = {} end
if not lc.opts.warning then lc.opts.warning = {} end
if not lc.opts.critical then lc.opts.critical = {} end
if not lc.opts.uom then lc.opts.uom = {} end
if not lc.opts.min then lc.opts.min = {} end
if not lc.opts.max then lc.opts.max = {} end
if not lc.opts.null_value then lc.opts.null_value = {} end
if not lc.opts.timeout then lc.opts.timeout = 10 end
if not lc.opts.netrc then lc.opts.netrc = 0 end
if not lc.opts.raw then lc.opts.raw = false end
if not lc.opts.perfdata_time then lc.opts.perfdata_time = 2 end

for k,v in pairs(ctx.default_parameter) do
    if lc.opts.parameter[k] == nil then
        lc.opts.parameter[k] = v
    end
end

ctx.zcurl_default_opts = {
    ssl_verifypeer = 0,
    ssl_verifyhost = 0,
    timeout = lc.opts.timeout,
    verbose = lc.opts.debug,
    followlocation = true,
    failonerror = true,
    netrc = lc.opts.netrc,
    cookiefile = '', -- in memory cookies
    customrequest = lc.opts.method,
    followlocation = lc.opts.follow,
    username = lc.opts.username,
    password = lc.opts.password,
    writefunction = ZCurl._store_response('body'),
}

if lc.opts.header and #lc.opts.header > 0 then
    ctx.zcurl_default_opts.httpheader = lc.opts.header
end

if lc.opts.cookies then
    lc.init_cache()
    ctx.zcurl_default_opts.cookiefile = lc.cachedir..'/cookies'
    ctx.zcurl_default_opts.cookiejar = lc.cachedir..'/cookies'
end

ctx.zcurl = ZCurl.new(ctx.zcurl_default_opts)

-- helpers
function build_url(url)
    if not url or #url == 0 then url = '/' end
    if not url:find('://') then
        if url:sub(1, 1) ~= '/' then url = '/'..url end
        if lc.opts.baseurl and #lc.opts.baseurl > 0 then url = lc.opts.baseurl..url
        else lc.die_unkn('Invalid URL: '..url) end
    end
    return url
end

function build_post_data(post_data, vars)
    if post_data then
        if post_data:sub(1, 1) == '@' then
            local fd, err = io.open(post_data:sub(2), 'rb')
            if not fd then lc.die_unkn('Cannot open data file: '..err) end
            post_data, err = fd:read('*a')
            fd:close()
            if not post_data then lc.die_unkn('Cannot read data file: '..err) end
        end
        local err
        post_data, err = lu.expand(post_data, vars, 'post-data')
        if not post_data then lc.die_unkn(err) end
    end
    return post_data
end

function query(zcurl, zcurlopts, decode, die_status)
    if not die_status then die_status = lc.UNKNOWN end
    zcurl:resetopts()
    zcurl:setopts(zcurlopts)
    local success, err = zcurl:perform()
    if not success then lc.die(die_status, 'Query failed: '..err) end
    lc.dump(zcurl.response.body, 'Dump response data')
    if decode then
        if decode == 'json' or (decode == true and zcurl.info.content_type:find('/json')) then
            ctx.zcurl.response.body_decoded, err = lc.cjson.decode(ctx.zcurl.response.body)
            if not ctx.zcurl.response.body_decoded then lc.die(die_status, 'JSON decode failed: '..err) end
        else lc.die(die_status, 'Unsupported data decode') end
        lc.dump(zcurl.response.body_decoded, 'Dump decoded response data')
    end
    ctx.curl_total_time = (ctx.curl_total_time or 0) + zcurl.info.total_time
end

-- query
if lc.opts.url and #lc.opts.url > 0 then
    local url = build_url(lc.opts.url)
    local post_data = build_post_data(lc.opts.post_data, lc.opts.parameter)
    query(ctx.zcurl, { url = url, postfields = post_data }, not lc.opts.raw and 'json')

    if ctx.zcurl.response.body_decoded then
        -- path[:label]
        for i = 1, #lc.opts.label do
            -- path is split[3], label is split[4]
            split = { lc.opts.label[i]:find('^([^:]+):?(.*)') }
            if #split == 0 then goto continue end

            local label = #split[4] > 0 and split[4] or split[3]
            local value, err = lu.getpath(ctx.zcurl.response.body_decoded, split[3],
                label, nil, tonumber(lc.opts.null_value[i]))
            if (err) then lc.pdebug('getpath: '..err) end

            table.insert(ctx.perfdata, {
                name = label,
                value = value,
                warning = lc.opts.warning[i],
                critical = lc.opts.critical[i],
                uom = lc.opts.uom[i],
                min = lc.opts.min[i],
                max = lc.opts.max[i],
            })
            ::continue::
        end
    end
end

-- addons
for _,v in ipairs(addon_code) do
    local success, err = pcall(v.code)
    if not success then
        lc.die(lc.UNKNOWN, "Failed to run addon '"..v.name.."' code: "..err)
    end
end

-- add curl time perfdata
if lc.opts.perfdata_time == 1 or (lc.opts.perfdata_time == 2 and #ctx.perfdata == 0) then
    table.insert(ctx.perfdata, {
        name = 'time',
        value = ctx.curl_total_time,
        uom = 's',
    })
end
lc.dump(ctx.perfdata, 'Dump perfdata')

-- set exit state and output from perfdata if not already done by addon
-- and if there are perfdata available
if not lc.exit_code then
    if #ctx.perfdata > 0 then
        lc.exit_code = lp.compute_perfdata(ctx.perfdata)
    end
end
if not lc.exit_message then
    if #ctx.perfdata > 0 then
        lc.exit_message = lp.format_output(ctx.perfdata, ctx.output_options)..'|'..
            lp.format_perfdata(ctx.perfdata, true)
    end
end