Search code examples
dockerredhatpodman

Interact with podman docker via socket in Redhat 9

I'm trying to migrate one of my dev boxes over from centos 8 to RHEL9. I rely heavily on docker and noticed when I tried to run a docker command on the RHEL box it installed podman-docker. This seemed to go smoothly; I was able to pull an image, launch, build, commit a new version without problem using the docker commands I knew already.

The problem I have encountered though is I can't seem to interact with it via the docker socket (which seems to be a link to the podman one).

If I run the docker command:

[@rhel9 ~]$ docker images
Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg.
REPOSITORY             TAG              IMAGE ID      CREATED      SIZE
docker.io/redhat/ubi9  dev_image        de371523ca26  6 hours ago  805 MB
docker.io/redhat/ubi9  latest           9ad46cd10362  6 days ago   230 MB

it has my images listed as expected. I should be able to also run:

[@rhel9 ~]$ curl --unix-socket /var/run/docker.sock -H 'Content-Type: application/json' http://localhost/images/json | jq .
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100     3  100     3    0     0     55      0 --:--:-- --:--:-- --:--:--    55
[]

but as you can see, nothing is coming back. The socket is up and running as I can ping it without issue:

[@rhel9 ~]$ curl -H "Content-Type: application/json" --unix-socket /var/run/docker.sock http://localhost/_ping
OK

I also tried the curl commands using the podman socket directly but it had the same results. Is there something I am missing or a trick to getting it to work so that I can interact with docker/podman via the socket?

Solution

  • I managed to solve my problem although I'm not entirely sure how the scenario came about. I was looking through the output of docker info and podman info and noticed that they both had the remote socket set as:

    remoteSocket:
    exists: true
    path: /run/user/1000/podman/podman.sock

    rather than /run/podman/podman.sock which is where I thought it was (this socket does actually exist on my machine). Looking at the systemd file for podman.socket I can see that the socket was specified as %t/podman/podman.sock and checking the man page for podman-system-service it specified the rootless socket as unix://$XDG_RUNTIME_DIR/podman/podman.sock (where my $XDG_RUNTIME_DIR=/run/user/1000.

    To get it all working with my software I just needed to make sure the DOCKER_HOST env variable was correctly set e.g. export DOCKER_HOST=unix:///run/user/1000/podman/podman.sock