gomonop - Various monitoring plugins in golang

This project is a collection of various monitoring plugins (such as Nagios, Centreon, or Icinga) written in golang. All plugins are available through a single executable, gomonop. The actual plugin can be selected either by creating a symlink to the main executable with the appropriate name or by calling the executable directly with the first argument being the name of the plugin.

This project is distributed under the terms of the GPLv3 license. Its source code is available on the Nocternity forge.

Plugins

SSL certificate expiry

The check_ssl_certificate plugin can be used to check that the certificate from a TLS service has not expired and is not going to expire shortly. It supports the following command-line flags:

• -H name/--hostname name: the host name to connect to.
• -P port/--port port: the TCP port to connect to.
• -W days/--warning days: a threshold, in days, below which a warning will be emitted for this service.
• -C days/--critical days: a threshold, in days, below which the plugin will indicate that the service is in a critical state.
• --ignore-cn-only: do not cause errors if a certificate does not have SANs and relies on the CN field.
• -a names/--additional-names names: a comma-separated list of DNS names that the certificate should also have.
• -s protocol/--start-tls protocol: protocol to use before requesting a switch to TLS. Supported protocols: smtp, sieve.

DNS zone serials

The check_zone_serial plugin can be used to check that the version of a zone served by a DNS is up-to-date compared to the same zone served by another, "reference" DNS. It supports the following command-line flags:

• -H name/--hostname name: the host name or address of the server to check.
• -P port/--port port: the port to use on the server to check (defaults to 53).
• -z zone: the zone to check.
• -r name/--rs-hostname name: the host name or address of the reference server.
• -p port/--rs-port port: the port to use on the reference server (defaults to 53).

Generic text match counter

The check_output_matches plugin can be used to count occurrences of strings in a program's output or in a text file, and compute its final status based on that.

It supports the following general command line flags:

• -f / --is-file indicates that the plugin will be reading from a text file instead of running another program;
• -s / --source is either the name of the file to read, or the command to execute. The command may include multiple arguments separated by single spaces; it does not support any form of quoting.
• -T / --timeout can set a timeout for the command. It is disabled by default.
• -S / --strict determines how unmatched lines are handled. By default they are ignored, but setting this flag will cause the plugin to enter CRITICAL mode if unmatched lines are found.

Other flags are available in order to configure the matches. The main flag is -m / --match, which adds a new match string to the set of checks to run. The checks are influenced by the following additional flags, which apply to all subsequent matches.

• -r / --regexp indicates that new matches will be based on regular expressions instead of substrings.
• -R / --no-regexp switches back to substring-based matches.
• -w / --warn can be used to set a warning range. It must be followed by a Nagios range specification.
• -W / --no-warn clears the warning range.
• -c / --critical can be used to set the critical range. It must be followed by a Nagios range specification.
• -C / --no-critical clears the critical range.

For example, the command below:

gomonop check_output_matches -s 'find /some/place' \
   -w 4 -r -m '^.*\.warn$' \
   -W -c 0 -R -m fatal

configures a warning if more than 4 files ending in .warn are found, and a critical state if any file with fatal in its name is found.

Building from source

The plugin can be built for the current host OS and architecture using make build. The actual executable will be created under the bin directory, in a subdirectory named after the host OS and architecture (e.g. bin/linux-amd64). The executable will be named gomonop, and a symlink to the executable for the host OS and architecture will be created under the bin directory.

It is possible to build for other architectures using make build-cross.