openstack team mailing list archive

[Adam Spiers <aspiers@xxxxxxxx>]

Dean Troyer (dtroyer@xxxxxxxxx) wrote:
> On Tue, May 1, 2012 at 2:11 PM, Adam Spiers <aspiers@xxxxxxxx> wrote:
> > As of my recent patch, --help is contextual in nova:
> 
> I hadn't seen that yet...
> 
> > and I have started work on some of the other commands too, so it would
> > be helpful if we could reach a consensus on this soon ... although
> > please let me know if I am wasting my time working on other commands
> > due to any imminent rewrites using python-openstack!
> 
> The continued existence of the project-specific commands is really up
> to the projects themselves.  I think it would be great to converge
> them on things like this, but trying to get them all to work the same
> is what led us to openstackclient due to backward compatibility and
> all.  My guess would be that the existing client binaries would live
> through the 'G' release even if we decided to deprecate them now.

OK, thanks for the info.  So what's the goal for this project - to
enter the incubation program? to become part of openstack-common?
Should it be added to http://wiki.openstack.org/Projects ?

> > I agree with Dolph - there is a precedent from other well-known
> > programs (git, hg, svn are the first ones I can think of) for --help
> > to behave differently depending on whether or not it was preceded by a
> > subcommand.  So my vote is that we should definitely aim to adhere to
> > this pattern.
> 
> How about detailing it in the HIG and once we get a command or two
> implemented with argument parsing we give it a shot?

I took a stab at this, but it's beginning to confirm the doubts which
I wrote about in https://lists.launchpad.net/openstack/msg10956.html
regarding the decision to have the verb preceding the noun:

    openstack create --help
    openstack help create

would require grouping of help for all the creation actions together
which doesn't make much sense to me.  These both seem to make more
sense:

    openstack endpoint --help
    openstack help endpoint

but would lead to overly long output unless they invoked man(1) on a
corresponding manual page all about endpoint management, similar to
how say, 'git remote --help' invokes the git-remote(1) man page which
covers management of git remotes.

The other option is to support a more fine-grained approach to help:

    openstack create endpoint --help
    openstack help create endpoint

and then make the help action require both, e.g.

    $ openstack help create
    Usage: openstack help create OBJECT-TYPE

    Which type of object do you want help creating?

    Available identity types:
        catalog         ec2-credentials endpoint         role
        service         tenant          user             user-password
        user-role

    Available compute types:
        absolute-limits actions         aggregate        bash-completion
        cloudpipe       console-log     credentials      diagnostics
        dns             dns-domain      endpoints        fixed-ip
        flavor          floating-ip     floating-ip-pool host
        image           keypair         meta(data)       quota
        quota-class     rate-limits     resource         root-password
        secgroup        secgroup-group  secgroup-rule    usage
        vnc-console     volume          volume-snapshot  volume-type
        x509-cert       x509-root-cert

    [...]

and ditto for 'openstack create --help'.  (Of course, this is just a
mockup and incorrectly lists some types which you would never create.)

Here are the classes of use cases I can think of:

  1. User has never/rarely used the (openstack) command before and
     needs to know overall structure of possible arguments and/or see
     a brief summary of common "get me started" arguments.

     Suggested implementation:
         openstack --help

  2. User has used the (openstack) command before but needs to check
     global options.

     Suggested implementation:
         openstack --help

  3. User wants to e.g. create something but isn't sure of the exact
     name of the type of the object to be created.

     Suggested implementation:
         openstack help create
         openstack create --help

  4. User wants to perform one or more actions on a particular type of
     object e.g. volume, but isn't sure which actions are available.

     Suggested implementation:
         ????

  5. User knows both the action and object type but needs to check
     details of options / extra positional arguments.

     Suggested implementation:
         openstack create endpoint --help
         openstack help create endpoint

Thoughts?