bug#59797: 30.0.50; [wishlist] Using namespaces in Tramp's kubernetes integration

[Eshel Yaron via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Michael Albinus <michael.albinus@gmx.de> writes:

> Eshel Yaron <me@eshelyaron.com> writes:
>
>> Hi Michael,
>
> Hi Eshel,
>
>> Michael Albinus <michael.albinus@gmx.de> writes:
>>
>>> Now we have kubernetes integrated in Tramp. We can access pods like
>>> "/kubernetes:POD:/path/to/file".
>>>
>>> However, kubernetes can much more. For all services (like pods) it
>>> creates DNS entries "<service-name>.<namespace-name>.svc.cluster.local".
>>> Should'nt we support this? It means should we allow to access kubernetes
>>> pods like "/kubernetes:POD.NAMESPACE:/path/to/file", including
>>> completion for namespace names?
>>
>> [...]
>>
>>> Finally, I've taken the stab and implemented something along these
>>> lines. It is a little bit different from earlier proposals.
>>>
>>> - You can now specify a container in the host name, dotted notation.
>>>   "/kubernetes:container.pod:" accesses the given container. If it is
>>>   not specified, as in "/kubernetes:pod:", the first container is taken.
>>>
>>> - You can now specify different context and namespace. Change the new
>>>   user options tramp-kubernetes-context or tramp-kubernetes-namespace
>>>   for this effect.
>>>
>>> Everything pushed to the Emacs and Tramp master repositories. The target
>>> is now Tramp 2.7 / Emacs 30. Comments welcome :-)
>>
>> Sorry for not chiming in when this discussion was still ongoing, and
>> thank you for your work on the Kubernetes integration.  I use it a lot.
>>
>> Would it be possible the reconsider adding an optional namespace to
>> Tramp's Kubernetes file name syntax?  I'm thinking of something like
>> "/kubernetes:[CONTAINER.]POD[.NAMESPACE]:/...".
>
> Possible. However, the syntax is ambiguous. If we have "/kubernetes:name1.name2:/..."
> it isn't clear what they are. name1 could be a container, and name2 a pod. Or
> name1 is a pod, and name2 is a namespace. Could we agree on another
> delimiter between POD and NAMESPACE?

You're absolutely right.  AFAIU from the Kubernetes documentation[0],
non-alphanumeric characters other than "-" and "." should be safe.
Maybe "@" would be the most natural choice?  "+" could work too I think.

>> My use case is that I want to start Dired for a (container in a) pod in
>> another namespace.  I can almost get there if I temporarily bind
>> tramp-kubernetes-namespace around the call to dired, but the binding
>> doesn't carry on to subsequent operations in the Dired buffer.  So an
>> explicit namespace in default-directory could help, I think.
>
> I see, it makes sense. My practical kubernetes experience is sparse; I
> would exploit you while implementing. At least for tests.

SGTM.

> Note also, that Emacs 30 is in pretest. Any such feature change will be
> targeted to Emacs 31 / Tramp 2.8.

Of course, that's fine.

Thank you!


[0] https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/
    https://kubernetes.io/docs/concepts/overview/working-with-objects/names/