Add dnsnames field & fix alias field by ashley-cui · Pull Request #29227 · podman-container-tools/podman

ashley-cui · 2026-07-20T16:56:32Z

Docker now reserves alias specfically for user-defined aliases, and uses another field, dnsnames, to hold all aliases, including container ID and name.
Part of docker v1.45 compat work, but this touches the cli too, since they updated it there too.

The NetworkSettings.Network.Aliases field in the `podman inspect` command and in returned in calls to GET /containers/{name:.*}/json API no longer contains the short container ID, and only contains user-provided network aliases. A new field, NetworkSettings.Network.DNSNames contains all aliases, container ID and name.

Luap99

approach looks good to me but tests are failing

Luap99 · 2026-07-24T16:33:51Z

+	networks := make([]types.NamedPerNetworkOptions, len(opts.Networks))
+	copy(networks, opts.Networks)


I don't think we need a copy here, the options we are given can be expected to be modified. This should not cause any negative downsides AFAIK

Luap99 · 2026-07-24T16:34:31Z

+	networks := make([]types.NamedPerNetworkOptions, len(opts.Networks))
+	copy(networks, opts.Networks)
+	for i := range networks {
+		networks[i].Aliases = append(slices.Clone(networks[i].Aliases), getExtraNetworkAliases(c)...)


This code could use slices.Concat() instead of the append and then could also get rid of that clone as concat will allocate a new slice always

Luap99 · 2026-07-24T16:35:17Z

 				netInfo := new(define.InspectAdditionalNetwork)
 				netInfo.NetworkID = getNetworkID(net.Name)
 				netInfo.Aliases = net.Aliases
+				netInfo.DNSNames = append(append([]string{c.Name()}, net.Aliases...), getExtraNetworkAliases(c)...)


same here and for the other nested appends consider using slices.Concat instead

Luap99

LGTM, thanks
@mheon PTAL

simek-m · 2026-07-31T12:23:56Z

Hi,
I completely missed this PR and independently opened a PR based on the v1.44 changelog adding the DnsNames too, my bad.

Comparing it apart from much better tests, different approach how the DnsNames field in the compat endpoint gets populated and change in the Aliases semantics, I noticed three other differences that I wanted to discuss:

I used getNetworkPodName(c) instead of c.Name(). Not sure what's more correct.
I deduplicated the DNSNames based on the Docker (Moby) implementation. When I test that, it looks like this in this branch:

{
  "Networks": {
    "podman": {
      ...
      "Aliases": [
        "844f6d6ce177"
      ],
      "DNSNames": [
        "dnstest",
        "844f6d6ce177",
        "844f6d6ce177"
      ]
    }
  }

The JIRA ticket also lists the libpod endpoint GET /libpod/containers/json to have DNSNames added (me adding that, also affected CLI).

Thanks.

ashley-cui · 2026-07-31T13:46:23Z

I think the second difference comes in because in 1.44 dnsnames are added, and in 1.45 alias is reserved exclusively for user-defined names? So in this PR aliases are empty and dont contain the short container ID unless the alias is set by the user using a option. And since the fields are changed in InspectAdditionalNetwork, the cli and libpod api should both be updated

simek-m · 2026-07-31T14:32:06Z

I think the second difference comes in because in 1.44 dnsnames are added, and in 1.45 alias is reserved exclusively for user-defined names? So in this PR aliases are empty and dont contain the short container ID unless the alias is set by the user using a option. And since the fields are changed in InspectAdditionalNetwork, the cli and libpod api should both be updated

Yes, I also understand it like you.
Sorry for the confusion, the output was from your branch's podman, but the container was created with my branch's podman and that's why the Aliases and short ID was there.

What I meant was only the duplicate value that would Docker deduplicate. Maybe it's a non-issue, though.

I'm not sure about the libpod endpoint:

➜  curl -s http://localhost:8080/v6.0.0/libpod/containers/json | jq .
[
  {
    "AutoRemove": false,
    "Command": [
      "top"
    ],
    "Created": "2026-07-31T16:19:20.388670122+02:00",
    "CreatedAt": "",
    "CIDFile": "",
    "Exited": false,
    "ExitedAt": -62135596800,
    "ExitCode": 0,
    "ExposedPorts": null,
    "Id": "2c58132268f74f004b6969e10b9998f434850702456bec011d00acfc2a3322cd",
    "Image": "docker.io/library/alpine:latest",
    "ImageID": "1991bd789d7184290c3cce84fd6af068b8b745e9bddf178661ce7f5ecf68135c",
    "IsInfra": false,
    "Labels": null,
    "Mounts": [],
    "Names": [
      "dnstest"
    ],
    "Namespaces": {},
    "Networks": [
      "podman"
    ],
    "Pid": 512040,
    "Pod": "",
    "PodName": "",
    "Ports": null,
    "Restarts": 0,
    "Size": null,
    "StartedAt": 1785507560,
    "State": "running",
    "Status": ""
  }
]

For comparison:

➜  curl -s http://localhost:8080/v6.0.0/libpod/containers/json | jq .
[
  {
    ...
    "Names": [
      "dnstest"
    ],
    "Namespaces": {},
    "Networks": [
      "podman"
    ],
    "DNSNames": {
      "podman": [
        "dnstest",
        "844f6d6ce177"
      ]
    },
    ...
  }
]

ashley-cui · 2026-07-31T14:41:58Z

Oh maybe not then. I'll update the libpod endpoint. I don't think we need to worry about dedup?

simek-m · 2026-07-31T14:49:43Z

Oh maybe not then. I'll update the libpod endpoint. I don't think we need to worry about dedup?

Yeah, I think that with your other changes it's less of an issue. You can probably set multiple same aliases (haven't tried that), but it's a completely minor thing.

Edit:

Yes, you can, but it's on you if you set the same alias multiple times.

{
  "Networks": {
    "podman": {
      ...
      "Aliases": [
        "alias",
        "alias"
      ],
      ...
      "DNSNames": [
        "dnstest",
        "alias",
        "alias",
        "19c1e70a47f0"
      ]
    }
  }
}

ashley-cui · 2026-08-03T19:52:57Z

Looks like the PR in its current state does have this behavior in the libpod endpoint:

curl -s --unix-socket /tmp/podman-test.sock http://d/v6.0.0/libpod/containers/dnscontainer/json | jq '.NetworkSettings.Networks.dnstest |  {Aliases, DNSNames}'
{
  "Aliases": [
    "myalias"
  ],
  "DNSNames": [
    "dnscontainer",
    "myalias",
    "e21b70f3817a",
    "myhostname"
  ]
}

Re-pushed for de-dup though

@simek-m PTAL, thanks!

Docker now reserves alias specfically for user-defined aliases, and uses another field, dnsnames, to hold all aliases, including container ID and name. Part of docker v1.45 compat work, but this touches the cli too, since they updated it there too. Signed-off-by: Ashley Cui <acui@redhat.com>

simek-m · 2026-08-04T11:16:13Z

Looks like the PR in its current state does have this behavior in the libpod endpoint:
curl -s --unix-socket /tmp/podman-test.sock http://d/v6.0.0/libpod/containers/dnscontainer/json | jq '.NetworkSettings.Networks.dnstest |  {Aliases, DNSNames}'
{
  "Aliases": [
    "myalias"
  ],
  "DNSNames": [
    "dnscontainer",
    "myalias",
    "e21b70f3817a",
    "myhostname"
  ]
}
Re-pushed for de-dup though

@simek-m PTAL, thanks!

Yes, re-tested and it looks all correct. I was wrong about libpod/containers/json, it's just libpod/containers/dnscontainer/json that should have DNSNames, sorry. Deduplication works too, thanks.

ashley-cui · 2026-08-04T13:30:10Z

@podman-container-tools/podman-maintainers PTAL and merge

baude · 2026-08-04T13:49:26Z

LGTM

Luap99 reviewed Jul 20, 2026

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Comment thread libpod/runtime_ctr.go Outdated

ashley-cui marked this pull request as draft July 20, 2026 17:43

ashley-cui force-pushed the dnsnames branch 2 times, most recently from fd925fb to 7f92308 Compare July 24, 2026 14:21

ashley-cui marked this pull request as ready for review July 24, 2026 14:35

ashley-cui force-pushed the dnsnames branch from 7f92308 to 7aefeb3 Compare July 24, 2026 14:51

Luap99 reviewed Jul 24, 2026

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ashley-cui force-pushed the dnsnames branch 2 times, most recently from 884e420 to d519dd4 Compare July 28, 2026 13:04

Luap99 approved these changes Jul 28, 2026

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Luap99 mentioned this pull request Jul 30, 2026

compat: Add DNSNames to GET /containers/{name:.*}/json #29349

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ashley-cui force-pushed the dnsnames branch from d519dd4 to 114131a Compare August 3, 2026 19:51

ashley-cui force-pushed the dnsnames branch from 114131a to d05eddd Compare August 3, 2026 20:19

simek-m approved these changes Aug 4, 2026

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baude merged commit 80bf6e6 into podman-container-tools:main Aug 4, 2026
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		networks := make([]types.NamedPerNetworkOptions, len(opts.Networks))
		copy(networks, opts.Networks)

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