Running Kamal via Docker with Colima

[Antvirf]

Most people are probably on Docker for Mac, but for those of us on Colima, the alias command provided in Kamal docs doesn't work as the sockets that should be mounted on the container are different. I've also ran into some other issues that I wanted to mention here. My target machine is an x86 Ubuntu box on the local network.

Troubleshooting SSH connection

With the default alias command, I could not connect to the target machine at all. Using the debug log level, I discovered an issue connecting to ssh-agent. Colima's SSH agent is in a different place so the path of the ssh agent needed to be updated as follows in the alias definition:

alias kamal='docker run -it --rm \
    -v "$(pwd):/workdir" \
    -v "$(colima ssh eval "echo \$SSH_AUTH_SOCK"):/ssh-agent" \
    -v "/var/run/docker.sock:/var/run/docker.sock" \
    -e SSH_AUTH_SOCK=/ssh-agent ghcr.io/basecamp/kamal:latest'

This allowed me to connect to the target machines, though kamal setup would fail at the build stage.

Local builder config - works fine

After trial and error, I foudn this config to work to at least get me past the stage of building the container:

# .config/deploy.yml
...
builder:
  multiarch: false
  local:
    arch: arm64
    host: unix:///Users/myusername/.colima/default/docker.sock

Remote builder config - fails

However my target machine is amd64 and hence in actuality I need to use multiarch, which I have not yet been able to get to work. This is the attempted config:

# .config/deploy.yml
builder:
  multiarch: true
  local:
    arch: arm64
    host: unix:///Users/myusername/.colima/default/docker.sock
  remote:
    arch: amd64
    host: ssh://[email protected]

And it errors out with the following message:

  ERROR (SSHKit::Command::Failed): docker exit status: 256
...
Successfully created context "kamal-app-multiarch-remote-amd64"
ERROR: failed to initialize builder kamal-app-core-multiarch-remote (kamal-app-multiarch-remote0): Cannot connect to the Docker daemon at unix:///Users/myusername/.colima/default/docker.sock. Is the docker daemon running?

The target machine is standard ubuntu, so the socket it should use is the default unix:///var/run/docker.sock.

Env:

• kamal version v0.16.1
• colima version 0.5.5