Proposal: support custom http verbs

[topliceanu]

rationale

• http/2 allows using custom http verbs (and I think they were allowed in http/1.1 as well) and there's no reason why vegeta can't support them.
• while not strictly RESTful, custom verbs have better semantics when working with resources.

context

• I ran echo "SUBSCRIBE http://localhost" | vegeta attack -http2 | tee /tmp/results.vegeta | vegeta report and I got back 2017/01/19 21:58:42 bad method: SUBSCRIBE and an empty report.

implementation

• vegeta attack gets a new options -allowed-methos=APPEND,SUBSCRIBE which is a list of comma-separated verbs allowed in targets. This list of allowed methods gets passed to the Targeter vegeta attack allows any ASCII upper-case word to be used as HTTP verb.
• I also added a test to make sure Targets are correctly configured
• a WIP PR is here https://github.com/tsenart/vegeta/pull/213 The new PR is here https://github.com/tsenart/vegeta/pull/217

[tsenart]

I'd just allow any string as method instead of defining the allowed ones per attack.

[topliceanu]

My thinking was that the targets file could come from a source you don't control, so you might need some method of checking. However you are absolutely right, allowing any word to be a verb is a MUCH simpler solution. I will open a PR for that.