/run/containerd/containerd.sock doesn't exist

[dpgeekzero]

This is a reasonably default docker deployment on OpenSUSE 15.6, the docker socket is still at /run/docker.sock.
The only way I found this was to use the new debug mode, copy out the docker run command and create the container manually.

Any chance the plugin could detect this at startup and start the container correctly?

ops:/home/core # docker info
Client:
 Version:    27.5.1-ce
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  0.11.2
    Path:     /usr/lib/docker/cli-plugins/docker-buildx

Server:
 Containers: 1
  Running: 0
  Paused: 0
  Stopped: 1
 Images: 1
 Server Version: 27.5.1-ce
 Storage Driver: overlay2
  Backing Filesystem: btrfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 oci runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 05044ec0a9a75232cad458027ca83437aae3f4da
 runc version: v1.1.14-0-g2c9f5602f0ba
 init version:
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.4.0-150600.23.47-default
 Operating System: openSUSE Leap 15.6
 OSType: linux
 Architecture: x86_64
 CPUs: 56
 Total Memory: 125.8GiB
 Name: ops
 ID: 155a47a7-2d14-4046-a9ce-207aa7479f01
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
 Live Restore Enabled: false

ops:/home/core # cat /etc/os-release
NAME="openSUSE Leap"
VERSION="15.6"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.6"
PRETTY_NAME="openSUSE Leap 15.6"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.6"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Leap"
LOGO="distributor-logo-Leap"

ops:/home/core # ls -l /run/docker.sock
srw-rw---- 1 root docker 0 Jun 19 17:35 /run/docker.sock
ops:/home/core # ls -l /run/container*
total 0

[dpgeekzero]

Unregistry output:

(base) core@ops:~> docker logs unregistry-pussh-21302-63372
time="2025-06-19T21:30:57Z" level=warning msg="No HTTP secret provided - generated random secret. This may cause problems with uploads if multiple registries are behind a load-balancer. To provide a shared secret, fill in http.secret in the configuration file or set the REGISTRY_HTTP_SECRET environment variable." go.version=go1.24.4
time="2025-06-19T21:30:57Z" level=info msg="redis not configured" go.version=go1.24.4
panic: unable to configure registry middleware (containerd): create containerd client: connection error: desc = "transport: Error while dialing: dial unix /run/containerd/containerd.sock: connect: connection refused"

goroutine 1 [running]:
github.com/distribution/distribution/v3/registry/handlers.NewApp({0x1458d40, 0x1d50080}, 0xc0003c7408)
        /go/pkg/mod/github.com/distribution/distribution/v3@v3.0.0/registry/handlers/app.go:335 +0x1d9a
github.com/uncloud/unregistry/internal/registry.NewRegistry({{0x12b75f8, 0x5}, {0x12d3792, 0x1f}, {0x12b6be8, 0x4}, {0x12b6be4, 0x4}, {0x12b6be0, 0x4}})
        /build/internal/registry/registry.go:64 +0x4b1
main.run({{0x12b75f8, 0x5}, {0x12d3792, 0x1f}, {0x12b6be8, 0x4}, {0x12b6be4, 0x4}, {0x12b6be0, 0x4}})
        /build/cmd/unregistry/main.go:63 +0x5e
main.main.func2(0xc000446308?, {0x12b6c5c?, 0x4?, 0x12b6c60?})
        /build/cmd/unregistry/main.go:42 +0x38
github.com/spf13/cobra.(*Command).execute(0xc000446308, {0xc00003c0a0, 0x0, 0x0})
        /go/pkg/mod/github.com/spf13/cobra@v1.9.1/command.go:1015 +0xaaa
github.com/spf13/cobra.(*Command).ExecuteC(0xc000446308)
        /go/pkg/mod/github.com/spf13/cobra@v1.9.1/command.go:1148 +0x46f
github.com/spf13/cobra.(*Command).Execute(...)
        /go/pkg/mod/github.com/spf13/cobra@v1.9.1/command.go:1071
main.main()
        /build/cmd/unregistry/main.go:57 +0x27b
(base) core@ops:~> ls -l /run/containerd/containerd.sock
total 0

[psviderski]

CPUs: 56
Total Memory: 125.8GiB

Wow! 😄

I can see containerd is used in docker info so there must be a running containerd daemon somewhere and the unix socket that docker uses to talk to. Can you please check if it's at /run/docker/containerd/containerd.sock?

Let's also check systemctl cat docker.service, can you see --containerd=XXX in ExecStart?

And finally, please try finding it on the file system if the options above didn't succeed:

sudo find /run -type s -name containerd.sock
# or
sudo find / -type s -name containerd.sock

[FGRibreau]

mince was in /run/docker/containerd/containerd.sock (Synology DSM)

[psviderski]

We can definitely try to check and use at least a few commonly known paths for the containerd.sock. Happy to merge if someone creates a PR for this

[yuzhichang]

@dpgeekzero @FGRibreau Fixed by PR #30