moby-engine package should not include /etc/docker/daemon.json

[paulmey]

Describe the bug
#8556 included a change that includes sane defaults in daemon.json. However, any consumer that deploys config using a configuration package now has a conflict.

file /etc/docker/daemon.json from install of azuredb-dataplane-common-0.0.19-1.cm2.noarch conflicts with file from package moby-engine-24.0.9-1.cm2.x86_64

To Reproduce
Steps to reproduce the behavior:

1. Create a package that deploys custom config using /etc/docker/daemon.json
2. Try to install your package on a system where
3. Scroll down to '....'
4. See error

Expected behavior
Since docker does not have a drop-in system or any other kind of composability for its config, the moby-engine package should not 'own' /etc/docker/daemon.json.
It might be a good idea to install a default in /etc/docker/daemon.json.default and copy it to /etc/docker/daemon.json in postinst if this file does not exist. That still achieves the goal of shipping sane defaults, while not taking ownership of the file.

[cpuguy83]

For this specific binary, upstream does not seem to try to resolve it from libexec.
For other ones, such as docker-init, it does look in /usr/libexec/docker/docker-init.
Should be pretty easy to convince upstream to do the same for docker-proxy.

It may be reasonable to look for docker-* binaries directly in /usr/libexec as well, but I don't think its currently doing this for any binary today.

[hbeberman]

Thanks for the report Paul Meyer (@paulmey)! I'm looking into the appropriate fix here and will prioritize making sure that /etc/docker/daemon.json is no longer owned by the moby-engine package, be that some %post trickery or enlightening moby-engine to assume a default path to docker-proxy.

[cpuguy83]

Opened this upstream: moby/moby#47804

[cpuguy83]

Upstream PR is merged.

[hbeberman]

ACK. Backporting the change into Azure Linux 2.0 now so we can drop the /etc/docker/daemon.json file.

[hbeberman]

The moby-engine-24.0.9-6.cm2.x86_64 package has just been published and no longer provides the /etc/docker/daemon.json file.