[Bug] soci cli fails if containerd address starts with "unix://"

[ollypom]

Description

If the containerd address starts with unix:// the soci cli will fail. I stumbled upon this when I had a containerd address set in a nerdctl config file and was using the nerdctl image push --snapshotter soci command.

Steps to reproduce the bug

$ sudo soci --address="unix:///var/run/containerd/containerd.sock" index ls                                                                                                                            
soci: failed to dial "unix:///var/run/containerd/containerd.sock": failed to build resolver: invalid (non-empty) authority: unix:

$ sudo soci --address="/var/run/containerd/containerd.sock" index ls
DIGEST                                                                     SIZE    IMAGE REF                                                         PLATFORM       MEDIA TYPE                                    CREATED      
sha256:b8005edf213e3ef96bff588690c618a778adb88801db7acf9256b0bdd841b006    1211    111222333444.dkr.ecr.eu-west-1.amazonaws.com/nginxdemo2:latest    linux/amd64    application/vnd.oci.image.manifest.v1+json    4m24s ago

Where as on nerdctl

$ sudo nerdctl --address="/var/run/containerd/containerd.sock" ps
CONTAINER ID    IMAGE    COMMAND    CREATED    STATUS    PORTS    NAMES

$ sudo nerdctl --address="unix:///var/run/containerd/containerd.sock" ps                                                                                                                               
CONTAINER ID    IMAGE    COMMAND    CREATED    STATUS    PORTS    NAMES

Describe the results you expected

$ sudo soci --address="unix:///var/run/containerd/containerd.sock" index ls                                                                                                                            
DIGEST                                                                     SIZE    IMAGE REF                                                         PLATFORM       MEDIA TYPE                                    CREATED      
sha256:b8005edf213e3ef96bff588690c618a778adb88801db7acf9256b0bdd841b006    1211    111222333444.dkr.ecr.eu-west-1.amazonaws.com/nginxdemo2:latest    linux/amd64    application/vnd.oci.image.manifest.v1+json    4m24s ago

Host information

1. OS: Amazon Linux 2
2. Snapshotter Version: 0.4.0
3. Containerd Version: 1.6.9

Any additional context or information about the bug

No response

[austinvazquez]

Hi @ollypom! Thanks for reporting the issue. I have tracked the issue back to we can simply strip unix:// from the containerd address when creating the client (similar to nerdctl). As of v0.4.0, we have a dependency on containerd's ctr for this functionality [to create containerd client]. We have work in-progress to remove this dependency. (See #874)

Once #874 is complete, then it should be straightforward to add address := strings.TrimPrefix("unix://", context.GlobalString("address"), opts...) to achieve the desired behavior.