A generic plugin for Nagios which checks json values from a given HTTP endpoint against argument specified rules and determines the status and performance data for that service.
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README.md

Nagios Json Plugin

This is a generic plugin for Nagios which checks json values from a given HTTP endpoint against argument specified rules and determines the status and performance data for that service.

Links

CLI Usage

Executing ./check_http_json.py -h will yield the following details:

usage: check_http_json.py [-h] [-d] [-s] -H HOST [-P PORT] [-p PATH]
                          [-t TIMEOUT] [-B AUTH] [-D DATA] [-A HEADERS]
                          [-f SEPARATOR]
                          [-w [KEY_THRESHOLD_WARNING [KEY_THRESHOLD_WARNING ...]]]
                          [-c [KEY_THRESHOLD_CRITICAL [KEY_THRESHOLD_CRITICAL ...]]]
                          [-e [KEY_LIST [KEY_LIST ...]]]
                          [-E [KEY_LIST_CRITICAL [KEY_LIST_CRITICAL ...]]]
                          [-q [KEY_VALUE_LIST [KEY_VALUE_LIST ...]]]
                          [-Q [KEY_VALUE_LIST_CRITICAL [KEY_VALUE_LIST_CRITICAL ...]]]
                          [-m [METRIC_LIST [METRIC_LIST ...]]]

Nagios plugin which checks json values from a given endpoint against argument
specified rules and determines the status and performance data for that
service

optional arguments:
  -h, --help            show this help message and exit
  -d, --debug           Debug mode.
  -s, --ssl             HTTPS mode.
  -H HOST, --host HOST  Host.
  -P PORT, --port PORT  TCP port
  -p PATH, --path PATH  Path.
  -t TIMEOUT, --timeout TIMEOUT
                        Connection timeout (seconds)
  -B AUTH, --basic-auth AUTH
                        Basic auth string "username:password"
  -D DATA, --data DATA  The http payload to send as a POST
  -A HEADERS, --headers HEADERS
                        The http headers in JSON format.
  -f SEPARATOR, --field_separator SEPARATOR
                        Json Field separator, defaults to "." ; Select element
                        in an array with "(" ")"
  -w [KEY_THRESHOLD_WARNING [KEY_THRESHOLD_WARNING ...]], --warning [KEY_THRESHOLD_WARNING [KEY_THRESHOLD_WARNING ...]]
                        Warning threshold for these values
                        (key1[>alias],WarnRange key2[>alias],WarnRange).
                        WarnRange is in the format [@]start:end, more
                        information at nagios-plugins.org/doc/guidelines.html.
  -c [KEY_THRESHOLD_CRITICAL [KEY_THRESHOLD_CRITICAL ...]], --critical [KEY_THRESHOLD_CRITICAL [KEY_THRESHOLD_CRITICAL ...]]
                        Critical threshold for these values
                        (key1[>alias],CriticalRange
                        key2[>alias],CriticalRange. CriticalRange is in the
                        format [@]start:end, more information at nagios-
                        plugins.org/doc/guidelines.html.
  -e [KEY_LIST [KEY_LIST ...]], --key_exists [KEY_LIST [KEY_LIST ...]]
                        Checks existence of these keys to determine status.
                        Return warning if key is not present.
  -E [KEY_LIST_CRITICAL [KEY_LIST_CRITICAL ...]], --key_exists_critical [KEY_LIST_CRITICAL [KEY_LIST_CRITICAL ...]]
                        Same as -e but return critical if key is not present.
  -q [KEY_VALUE_LIST [KEY_VALUE_LIST ...]], --key_equals [KEY_VALUE_LIST [KEY_VALUE_LIST ...]]
                        Checks equality of these keys and values
                        (key[>alias],value key2,value2) to determine status.
                        Multiple key values can be delimited with colon
                        (key,value1:value2). Return warning if equality check
                        fails
  -Q [KEY_VALUE_LIST_CRITICAL [KEY_VALUE_LIST_CRITICAL ...]], --key_equals_critical [KEY_VALUE_LIST_CRITICAL [KEY_VALUE_LIST_CRITICAL ...]]
                        Same as -q but return critical if equality check
                        fails.
  -m [METRIC_LIST [METRIC_LIST ...]], --key_metric [METRIC_LIST [METRIC_LIST ...]]
                        Gathers the values of these keys (key[>alias],UnitOfMe
                        asure,WarnRange,CriticalRange,Min,Max) for Nagios
                        performance data. More information about Range format
                        and units of measure for nagios can be found at
                        nagios-plugins.org/doc/guidelines.html Additional
                        formats for this parameter are: (key[>alias]),
                        (key[>alias],UnitOfMeasure),
                        (key[>alias],UnitOfMeasure,WarnRange,CriticalRange).

Examples

Key Naming

Data for key value:

{ "value": 1000 }

Data for key capacity.value:

{
    "capacity": {
        "value": 1000
    }
}

Data for key (0).capacity.value:

[
    {
        "capacity": {
            "value": 1000
        }
    }
]

Data for separator -f _ and key (0)_gauges_jvm.buffers.direct.capacity_value:

[
    {
        "gauges": {
            "jvm.buffers.direct.capacity":
                "value": 1000
            }
        }
    }
]

Data for keys ring_members(0), ring_members(1), ring_members(2):

{
    "ring_members": [
        "riak1@127.0.0.1",
        "riak2@127.0.0.1",
        "riak3@127.0.0.1"
    ]
}

Thresholds and Ranges

Data:

{ "metric": 1000 }

Relevant Commands

  • Warning: ./check_http_json.py -H <host>:<port> -p <path> -w "metric,RANGE"

  • Critical: ./check_http_json.py -H <host>:<port> -p <path> -c "metric,RANGE"

  • Metrics with Warning: ./check_http_json.py -H <host>:<port> -p <path> -w "metric,RANGE"

  • Metris with Critical:

      ./check_http_json.py -H <host>:<port> -p <path> -w "metric,,,RANGE"
      ./check_http_json.py -H <host>:<port> -p <path> -w "metric,,,,MIN,MAX"
    

Range Definitions

  • Format: [@]START:END
  • Generates a Warning or Critical if...
    • Value is less than 0 or greater than 1000: 1000 or 0:1000
    • Value is greater than or equal to 1000, or less than or equal to 0: @1000 or @0:1000
    • Value is less than 1000: 1000:
    • Value is greater than 1000: ~:1000
    • Value is greater than or equal to 1000: @1000:

More info about Nagios Range format and Units of Measure can be found at https://nagios-plugins.org/doc/guidelines.html.

Using Headers

  • ./check_http_json.py -H <host>:<port> -p <path> -A '{"content-type": "application/json"}' -w "metric,RANGE"

Nagios Installation

Requirements

  • Python

Configuration

Assuming a standard installation of Nagios, the plugin can be executed from the machine that Nagios is running on.

cp check_http_json.py /usr/local/nagios/libexec/plugins/check_http_json.py
chmod +x /usr/local/nagios/libexec/plugins/check_http_json.py

Add the following service definition to your server config (localhost.cfg):


define service {
        use                             local-service
        host_name                       localhost
        service_description             <command_description>
        check_command                   <command_name>
        }

Add the following command definition to your commands config (commands.config):


define command{
        command_name    <command_name>
        command_line    /usr/bin/python /usr/local/nagios/libexec/plugins/check_http_json.py -H <host>:<port> -p <path> [-e|-q|-w|-c <rules>] [-m <metrics>]
        }

More info about options in Usage.

License

Copyright 2014-2015 Drew Kerrigan.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.