Check if file present

[oscar123mendoza]

This is good for people who want to make sure a file is there and alert if the file is no there. For my case this is good for Nginx matchers. We have several matchers for our micro services and we want to loop through them to confirm they are there.

Pull Request Checklist

Is this in reference to an existing issue?
Nope.

General

• Update Changelog following the conventions laid out on Keep A Changelog

• Update README with any necessary configuration snippets

• Binstubs are created if needed

• RuboCop passes

• Existing tests pass

New Plugins

• Tests

• Add the plugin to the README

• Does it have a complete header as outlined here

Purpose

Known Compatablity Issues

[majormoses]

We discussed this a bit over slack and I gave some suggestions/pointers.

[oscar123mendoza]

$ /opt/sensu/embedded/bin/check-file-exists.rb -c "/etc/sensu/conf.d/checks/psql-pointer-process-check.json"
CheckFileExists CRITICAL: 1 matching file(s) found: /etc/sensu/conf.d/checks/psql-pointer-process-check.json

$ /opt/sensu/embedded/bin/check-file-exists.rb -w "/etc/sensu/conf.d/checks/psql-pointer-process-check.json"
CheckFileExists WARNING: 1 matching file(s) found: /etc/sensu/conf.d/checks/psql-pointer-process-check.json

$ /opt/sensu/embedded/bin/check-file-exists.rb -u "/etc/sensu/conf.d/checks/psql-pointer-process-check.json"
CheckFileExists UNKNOWN: 1 matching file(s) found: /etc/sensu/conf.d/checks/psql-pointer-process-check.json

$ /opt/sensu/embedded/bin/check-file-exists.rb -p "/etc/sensu/conf.d/checks/psql-pointer-process-check.json"     
CheckFileExists OK: Matching file(s) found: /etc/sensu/conf.d/checks/psql-pointer-process-check.json