[lxc-devel] API wishlist

[Serge Hallyn]

Quoting Stéphane Graber (stgraber at ubuntu.com):
> So, I've been thinking a bit about what functions we're currently
> missing in the API which would make the bindings and scripts much easier.
> 
> So far, I've been thinking of:
>  - get_cgroup_item(cgroup, key)
>  - set_cgroup_item(cgroup, key, value)

Remind me - do we want these to affect the container if it is running
as well?  Or only the in-memory container representation (optionally
to be saved to disk on the next c->save_config()?

Oh right, in lxccontainer.h there are also commented-out
commit_cgroups() and reread_cgroups().  I guess I was thinking
that you'd do set_cgroup_item(...) to only change in-memory settings,
commit_cgroups() to apply to a running container, and reread_cgroups()
to re-load from configuration file?  No we don't need reread_cgroups()
I don't think.

>  - attach(namespaces, command)
>    Attach to the provided list of namespaces and runs the command inside
> the container.

+1 for all of these.  I'd like to finish with syslog_ns before I get
to those though.

>  - clone(container)
>    Used in a similar way to create() but instead of creating a new
> rootfs, copies the one from an existing container. It gets a bit
> trickier when we need to support weird storage backends.

I'd like far more detailed discussion on the API for that before I
consider coding :)

>  - console(tty)
>    Similar to what lxc-console does, attach to the given tty number and
> let the user exit with ctrl+a-q

Not sure how straightforward this is or we want it to be.  Do we just
want it to usurp the caller's console like lxc-console does?

>  - get_version() (not container specific)
>  - get_lxc_path() (not container specific)
>    Returns the storage path for the containers.
>    Defaults to LXCPATH.
>  - set_lxc_path(path) (not container specific)

Should be trivial.

> Looking at my todolist for this cycle, the highest priority ones for me
> would be:
>  1) get_lxc_path()
>  2) set_lxc_path()
>  3) get_cgroup_item()
>  4) set_cgroup_item()
> 
> The rest I currently already have by wrapping around the lxc-* tools,
> but it'd be nice to stop doing that and having those calls in the API so
> we can rebase the tools on the API and make things a bit more consistent.
> 
> -- 
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
> 



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