implement --response-code functionality

[agoddard]

Allow checking for an expected http status code, exiting 0 if the expected code matches the returned code. This is to implement checks to ensure that a site responds with a particular status code, such as a 403, or a 301. For reference, in the legacy ruby version of this plugin, this functionality was implemented as --response code <code> https://github.com/sensu-plugins/sensu-plugins-http/blob/master/bin/check-http.rb#L30-L31

[calebhailey]

@jspaleta I wonder if we could implement this one as a metric tag + metric threshold check?

[nixwiz]

@agoddard something to consider in implementing this would be its behavior with respect to the --redirect-ok flag. May require additional documentation (e.g. you cannot use --redirect-ok when doing --response-code 301) and the already noted caveats for --redirect-ok.

[asachs01]

@agoddard is there an internal ref for this one?

[calebhailey]

I'm wondering if --redirect-ok and the proposed --reponse-code implementation are necessarily mutually exclusive? What if I want to configure a check to expect a response-code from it's final destination, even if that's after following a redirect?

[calebhailey]

Should --response-code be --response-codes (plural)? Then perhaps you could pair --redirect-ok with --response-codes 301,202, meaning any number of 301 redirects and a 202 response code are acceptable result for the check?

[agoddard]

Maybe it can be a single code or an array, and when it is an array the order matters, so then you can say "when I hit this redirecting URL with redirect-ok, I want to know that the place I end up gives me a 200" and then of providing an Array, then "when I hit this redirecting URL, I should get a 302 on the way to the 200" [302,200]

[fguimond]

Let’s implement the suggested changes allowing the concurrent usage of --redirect-ok and --response-code, by applying the response code validation against the final redirect destination. --response-code should allow for a coma-separated list of valid response codes. As an example --response-code '200,201' would allow the final response code to be either 200 or 201.

[chavakula]

@fguimond , pull request has been raised for the same : #28

[fguimond]

@fguimond to release the next version of the plugin.