compat: Add DNSNames to GET /containers/{name:.*}/json

[simek-m]

Docker Engine API v1.44 introduces a new field named DNSNames containing all non-fully qualified DNS names a container takes on a specific network for the GET /containers/{name:.*}/json endpoint.

• Populate DNSNames for the compat endpoints GET /containers/json and GET /containers/{name:.*}/json (the Docker changelog mentions only /containers/{name:.*}/json, but it's the same moby structure).
• Add the DNSNames field to GET /libpod/containers/json (added to entities.ListContainer) too based on RUN-3314 description - works with podman list/ps --format '{{.DNSNames}}'

Fixes: https://redhat.atlassian.net/browse/RUN-3314

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Does this PR introduce a user-facing change?

Add field DNSNames to the compat endpoints GET /containers/json and GET /containers/{name:.*}/json and to the libpod endpoint GET /libpod/containers/json.

Example output

➜ curl -s http://localhost:8080/v1.44/containers/dnstest/json | jq '.NetworkSettings'
{
  "SandboxID": "",
  "SandboxKey": "/run/netns/netns-a3fa06b8-40a8-b0e7-10ab-c2d73127538f",
  "Ports": {},
  "Networks": {
    "podman": {
      "IPAMConfig": null,
      "Links": null,
      "Aliases": [
        "844f6d6ce177"
      ],
      "DriverOpts": null,
      "GwPriority": 0,
      "NetworkID": "2f259bab93aaaaa2542ba43ef33eb990d0999ee1b9924b557b7be53c0b7a1bb9",
      "EndpointID": "",
      "Gateway": "10.88.0.1",
      "IPAddress": "10.88.0.186",
      "MacAddress": "ee:76:15:30:c1:7d",
      "IPPrefixLen": 16,
      "IPv6Gateway": "",
      "GlobalIPv6Address": "",
      "GlobalIPv6PrefixLen": 0,
      "DNSNames": [
        "dnstest",
        "844f6d6ce177"
      ]
    }
  }
}

➜  podman git:(main) ✗ curl -s http://localhost:8080/v1.44/containers/json | jq '.[].NetworkSettings'
{
  "Networks": {
    "podman": {
      "IPAMConfig": null,
      "Links": null,
      "Aliases": [
        "844f6d6ce177"
      ],
      "DriverOpts": null,
      "GwPriority": 0,
      "NetworkID": "2f259bab93aaaaa2542ba43ef33eb990d0999ee1b9924b557b7be53c0b7a1bb9",
      "EndpointID": "",
      "Gateway": "10.88.0.1",
      "IPAddress": "10.88.0.186",
      "MacAddress": "ee:76:15:30:c1:7d",
      "IPPrefixLen": 16,
      "IPv6Gateway": "",
      "GlobalIPv6Address": "",
      "GlobalIPv6PrefixLen": 0,
      "DNSNames": [
        "dnstest",
        "844f6d6ce177"
      ]
    }
  }
}

➜  curl -s http://localhost:8080/v6.0.0/libpod/containers/json | jq .
[
  {
    "AutoRemove": false,
    "Command": [
      "top"
    ],
    "Created": "2026-07-30T14:26:23.637667619+02:00",
    "CreatedAt": "",
    "CIDFile": "",
    "Exited": false,
    "ExitedAt": -62135596800,
    "ExitCode": 0,
    "ExposedPorts": null,
    "Id": "844f6d6ce177a4d5d89aba9849b246e9ca7fa26d6e2c468eee988ad56d2cca88",
    "Image": "docker.io/library/alpine:latest",
    "ImageID": "1991bd789d7184290c3cce84fd6af068b8b745e9bddf178661ce7f5ecf68135c",
    "IsInfra": false,
    "Labels": null,
    "Mounts": [],
    "Names": [
      "dnstest"
    ],
    "Namespaces": {},
    "Networks": [
      "podman"
    ],
    "DNSNames": {
      "podman": [
        "dnstest",
        "844f6d6ce177"
      ]
    },
    "Pid": 366232,
    "Pod": "",
    "PodName": "",
    "Ports": null,
    "Restarts": 0,
    "Size": null,
    "StartedAt": 1785414383,
    "State": "running",
    "Status": ""
  }
]

[simek-m]

xref-helpmsgs-manpages: 'podman container list --format {{.DNSNames' is a nested structure. Please add '...' to man page.
xref-helpmsgs-manpages: 'podman container ps --format {{.DNSNames' is a nested structure. Please add '...' to man page.
xref-helpmsgs-manpages: 'podman ps --format {{.DNSNames' is a nested structure. Please add '...' to man page.
make: *** [Makefile:632: xref-helpmsgs-manpages] Error 1

Oh, I'll fix this.

[Luap99]

I have not really looked at the details here but I already reviewed #29227 from @ashley-cui. Can you cross check that, which version is needed?

[simek-m]

I have not really looked at the details here but I already reviewed #29227 from @ashley-cui. Can you cross check that, which version is needed?

Oh, thank you. I knew that v1.45 mentions:

The Aliases field returned in calls to GET /containers/{name:.*}/json no longer contains the short container ID, but instead will reflect exactly the values originally submitted to the POST /containers/create endpoint. The newly introduced DNSNames should now be used instead when short container IDs are needed.

but unfortunately completely missed that Ashley did this one too:(
It's a bit chaotic working on multiple versions in parallel (some changelogs were implemented from even higher versions than v1.45, but there are some missing parts from versions below 1.44 according to Nicola).

Well, at least I've learnt a bit about networking. I implemented it a bit differently and Ashley's version has much better tests. I'll comment there.

[simek-m]

Closing in favor of #29227