Sort containers by `Labels.com.docker.compose.container-number`

[AkramiPro]

Thank you for the great work on docker-gen.

I want to sort my containers using container-number, but I think this is not supported yet, or I might be doing it wrong.

sort by Labels.com.docker.compose.container-number

{{ $backends := sortObjectsByKeysAsc (whereLabelValueMatches . "com.example.haproxy.backend" "true") "Labels.com.docker.compose.container-number" }}

result:

    server app-3 172.25.0.3:443
    server app-9 172.25.0.4:443
    server app-8 172.25.0.5:443
    server app-4 172.25.0.6:443
    server app-7 172.25.0.7:443
    server app-10 172.25.0.8:443
    server app-1 172.25.0.9:443
    server app-2 172.25.0.10:443
    server app-6 172.25.0.11:443
    server app-5 172.25.0.12:443

sort by Name

{{ $backends := sortObjectsByKeysAsc (whereLabelValueMatches . "com.example.haproxy.backend" "true") "Name" }}

result:

    server app-1 172.25.0.9:443
    server app-10 172.25.0.8:443
    server app-2 172.25.0.10:443
    server app-3 172.25.0.3:443
    server app-4 172.25.0.6:443
    server app-5 172.25.0.12:443
    server app-6 172.25.0.11:443
    server app-7 172.25.0.7:443
    server app-8 172.25.0.5:443
    server app-9 172.25.0.4:443

[SchoNie]

It's being sorted lexicographically (as strings), which causes "10" to come before "2" (because "1" < "2").
This happens because sortObjectsByKeysAsc performs string-based sorting.

Could you pad the container numbers labels with a 0? So 1 becomes 01, 2 becomes 02 and so on.

[buchdag]

@AkramiPro that's actually a bug, docker-gen treat the full string passed to sortObjectsByKeysAsc as a key path expression, but for Labels this is not the case and everything after Labels. should be treated as a single key string.

In other words sortObjectsByKeysAsc $containers "Labels.com.docker.compose.container-number" currently expect something like this:

{
  "Labels": {
    "com": {
      "docker":{
        "compose": {
          "container_number": 1
        }
      }
    }
  }
}

While in reality you have:

{
  "Labels": {
    "com.docker.compose.container_number": 1
  }
}

[buchdag]

@AkramiPro I've got a fix but that will get you to the same point as what @SchoNie describe : since sortObjectsByKeysAsc performs string based sorting, sorting on unpadded integer (like the com.docker.compose.container-number label) will give you the same result as sorting by container Name.

Edit: I got that fixed too.

[AkramiPro]

@buchdag thanks for fixing ❤️🙏

[buchdag]

@AkramiPro could you test the nginxproxy/docker-gen:fix-679 image and confirm that it fixes your issue ?

[AkramiPro]

@AkramiPro could you test the nginxproxy/docker-gen:fix-679 image and confirm that it fixes your issue ?

yes it works
thank you @buchdag

    server app-1 172.25.0.9:443
    server app-2 172.25.0.10:443
    server app-3 172.25.0.3:443
    server app-4 172.25.0.6:443
    server app-5 172.25.0.12:443
    server app-6 172.25.0.11:443
    server app-7 172.25.0.7:443
    server app-8 172.25.0.5:443
    server app-9 172.25.0.4:443
    server app-10 172.25.0.8:443

[buchdag]

@AkramiPro sorry but it look like the fix caused other templates function to break (#683).

I'll have to revert this for now and re-fix it properly later.