Help text broken when using an invalid flag

[mvdan]

 $ tyk --help
Tyk API Gateway.

        Usage:
                tyk [options]

        Options:
                -h --help                    Show this screen
                --conf=FILE                  Load a named configuration file
                --port=PORT                  Listen on PORT (overrides confg file)
                --memprofile                 Generate a memory profile
                --cpuprofile                 Generate a cpu profile
                --httpprofile                Expose runtime profiling data via HTTP
                --debug                      Enable Debug output
                --import-blueprint=<file>    Import an API Blueprint file
                --import-swagger=<file>      Import a Swagger file
                --create-api                 Creates a new API Definition from the blueprint
                --org-id=><id>               Assign the API Defintition to this org_id (required with create)
                --upstream-target=<url>      Set the upstream target for the definition
                --as-mock                    Creates the API as a mock based on example fields
                --for-api=<path>             Adds blueprint to existing API Defintition as version
                --as-version=<version>       The version number to use when inserting
                --log-instrumentation        Output instrumentation data to stdout

 $ tyk --foo
Usage:
                tyk [options]

The second execution should say something like invalid flag: --foo and print the whole help, or at least tell the user that they can do --help to get it.

Not high priority, but filing to remind myself.

[mvdan]

Seems not to be our problem: docopt/docopt.go#37

docopt.go is also somewhat abandoned, with no commits for over a year. Let's look at this again in a few months. If it's still abandoned, switching to a better flag parsing library (read: non-buggy) might be a good option.

[mvdan]

Doesn't look good - another half year and the library is still dead, including that bug. We should definitely switch to another for 2.5.

[mvdan]

@joshblakeley is replacing docopt with kingpin, so this will be fixed as part of that.