When trying to use an invalid flag, the CLI currently prints the a short
error message, instructions to use the `--help` flag to learn about the
correct usage, followed by the command's usage output.
While this is a common convention, and may have been a nice gesture when
docker was still young and only had a few commands and options ("you did
something wrong, but here's an overview of what you can use"), that's no
longer the case, and many commands have a _very_ long output.
The result of this is that the error message, which is the relevant
information in this case - "You mis-typed something" - is lost in the
output, and hard to find (sometimes even requiring scrolling back).
The output is also confusing, because it _looks_ like something ran
successfully (most of the output is not about the error!).
Even further; the suggested resolution (try `--help` to see the correct
options) is rather redundant, because running teh command with `--help`
produces _exactly_ the same output as was just showh, baring the error
message. As a fun fact, due to the usage output being printed, the
output even contains not one, but _two_ "call to actions";
- `See 'docker volume --help'.` (under the erro message)
- `Run 'docker volume COMMAND --help' for more information on a command.`
(under the usage output)
In short; the output is too verbose, confusing, and doesn't provide
a good UX. Let's reduce the output produced so that the focus is on the
important information.
This patch:
- Changes the usage to the short-usage.
- Prefixes the error message with the binary / root-command name
(usually `docker:`) to be consistent with `unknon command`, and helps
to distinguish where the message originated from (the `docker` CLI in
this case).
- Adds an empty line between the error-message and the "call to action"
(`Run 'docker volume --help' ...` in the example below). This helps
separating the error message ("unkown flag") from the call-to-action.
Before this patch:
docker volume --no-such-flag
unknown flag: --no-such-flag
See 'docker volume --help'.
Usage: docker volume COMMAND
Manage volumes
Commands:
create Create a volume
inspect Display detailed information on one or more volumes
ls List volumes
prune Remove unused local volumes
rm Remove one or more volumes
update Update a volume (cluster volumes only)
Run 'docker volume COMMAND --help' for more information on a command.
With this patch:
docker volume --no-such-flag
docker: unknown flag: --no-such-flag
Usage: docker volume COMMAND
Run 'docker volume --help' for more information
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
- remove check for "A self-sufficient runtime for containers"; really
not important to check for.
- don't make the checks positional (just match that we find them, and
that we don't find them multiple times)
- account for leading whitespace to change instead of hard-coding the
number of spaces before output.
- change the badopt check; I think it should be sufficient to check
that the bad option was printed and that "run --help" output is
printed.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Plugins are expected to be management commands ("docker <object> <verb>").
This patch modified the usage output to shown plugins in the "Management commands"
section.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
- The placement of the vendor is now in the end of the line.
- A '*' is now added as suffix of plugins' top level commands.
Signed-off-by: Ulysses Souza <ulysses.souza@docker.com>
They were listed twice in `docker --help` (but not `docker help`), since the
stubs were added in both `tryRunPluginHelp` and the `setHelpFunc` closure.
Calling `AddPluginStubCommands` earlier in `setHelpFunc` before the call to
`tryRunPluginHelp` is sufficient. Also it is no longer necessary to add just
valid plugins (`tryRunPluginHelp` handles invalid plugins correctly) so remove
that logic (which was in any case broken for e.g. `docker --help`).
Update the e2e test to check for duplicate entries and also to test `docker
--help` which was previously missed.
Signed-off-by: Ian Campbell <ijc@docker.com>
To do this we add a stub `cobra.Command` for each installed plugin (only when
invoking `help`, not for normal running).
This requires a function to list all available plugins so that is added here.
Signed-off-by: Ian Campbell <ijc@docker.com>
Sebastiaan van Stijn
Alano Terblanche
Ian Campbell
Silvin Lubecki
Ulysses Souza