In the initial implementation I thought it would be good to not pass on the
deprecation to plugins (since they are new). However it turns out this causes
`docker helloworld -h` to print a spurious "pflag: help requested" line:
$ docker helloworld -h
pflag: help requested
See 'docker helloworld --help'.
Usage: docker helloworld [OPTIONS] COMMAND
A basic Hello World plugin for tests
...
Compared with:
$ docker ps -h
Flag shorthand -h has been deprecated, please use --help
Usage: docker ps [OPTIONS]
This is in essence because having the flag undefined hits a different path
within cobra, causing `c.execute()` to return early due to getting an error
(`flag.ErrHelp`) from `c.ParseFlags`, which launders the error through our
`FlagErrorFunc` which wraps it in a `StatusError` which in turn defeats an `if
err == flag.ErrHelp` check further up the call chain. If the flag is defined we
instead hit a path which returns a bare `flag.ErrHelp` without wrapping it.
I considered updating our `FlagErrorFunc` to not wrap `flag.ErrHelp` (and then
following the chain to the next thing) however while doing that I realised that
the code for `-h` (and `--help`) is deeply embedded into cobra (and its flags
library) such that actually using `-h` as a plugin argument meaning something
other than `help` is basically impossible/impractical. Therefore we may as well
have plugins behave identically to the monolithic CLI and support (deprecated)
the `-h` argument.
With this changed the help related blocks of `SetupRootCommand` and
`SetupPluginRootCommand` are now identical, so consolidate into
`setupCommonRootCommand`.
Tests are updated to check `-h` in a variety of scenarios, including the happy
case here.
Signed-off-by: Ian Campbell <ijc@docker.com>
8f3798cf04