Add pods created by play kube to a default network

[ancosma]

In order to allow pods to reach other pods (as in Kubernetes) they all need to be added to the same network. A network is created (if it doesn't exist) and pods created by play-kube are added to that network. When network options are passed to kube command the pods are not attached to the default kube network.

Signed-off-by: Andrei Natanael Cosma [email protected]

Does this PR introduce a user-facing change?

Behavior of play-kube is changed to create a network (podman-kube) if it doesn't exists and adds pods created by kube-play to that network, which allows pods to reach other pods - as in Kubernetes.

It partially overlaps with #12965

[rhatdan]

@Luap99 @mheon @umohnani8 WDYT

Should we take down the network, when all pods/containers are removed?

[mheon]

I see no reason to remove it.

Overall this feels like a good change. I would like to see it documented in the manpages, though.

[Luap99]

I don't think we should remopve this network, implementing this without TOCTOU race would require us to lock almost everything which can lead to performance problems.

Please add a test for this and remove [NO NEW TEST NEEDED] from your commit. This is only intended for things that cannot be tested in CI.

[rhatdan]

@mheon @Luap99 PTAL

Probably should get this into podman 4.3?

[mheon]

Changes LGTM

[Luap99]

LGTM

@mheon Do you want to include this in v4.3 or wait for v4.4?

[openshift-ci]

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[mheon]

/lgtm
Since I'm getting distracted by other things and haven't gotten the release out yet, I can just rebase the 4.3 branch to include this before I cut the tag.

[brendon]

Just wondering if there's any documentation around how to access a container in another pod from the current pod in terms of host names?

[mheon]

The pod name is the hostname. No domain name should be necessary, appropriate search domains are set to ensure that.

[brendon]

Excellent :) Yes I figured that out with a bit of trial and error. It's very elegant, well done!