Allow container names to be supplied to weave ps

[bboreham]

So, weave ps will still show you all containers, but weave ps mycontainer will just show you that one.

If you give a nonexistent name you get no output, which is consistent with Unix ps.

[inercia]

+1

[rade]

I am not completely sold in this. docker ps doesn't take a container argument. And filtering by container id is just one 'grep' away. So what's the rationale here? Performance?

[bboreham]

I needed something like this to run smoke-tests for IPAM.

docker ps does have a --filter name=foo option (on master).

But yes, performance. In order to grep the weave ps output you need the short form of the container hex ID, which needs a docker inspect, possibly remotely. Also, it's much more inefficient to obtain details on every container then grep out the ones you don't need.

[rade]

ok. rationale accepted.

AFAICT, when this is fed a name, the output will contain that name, not the container id. Shouldn't the output always contain the id?

Docs could perhaps do with a sentence mentioning the extra functionality.

[bboreham]

While putting the hex ID in the output would be consistent, it seems rather a complex implementation to add for little benefit. If the caller of weave ps knows the name of a container and doesn't know the ID, then has to do extra work to be able to match them up.

[bboreham]

Doc change added.