Feature request: Health check

[vincentjorgensen]

Hi! I love this app. I created a docker compose file to use it—in lieu of k3d registry create—so that I can explicitly set the IP address it listens on. While doing so, I realized the dockerfile doesn't have a HEALTHCHECK directive. No biggie, but it would be nice. Even just something to safely fill this section in:

services:
  registry:
  healthcheck:
    test: ["CMD", "curl", "-f", "http://localhost"] # WHAT SHOULD GO HERE?
    interval: 1m30s
    timeout: 10s
    retries: 3
    start_period: 40s
    start_interval: 5s

If any other users have suggestions that do not involve modifying the code, I'm all ears!

thanks again for the great service. Cheers, Vincent

[vincentjorgensen]

Update:
I'm trying

test: ["CMD", "nc", "-vz", "localhost", "5000"]

Any reason that's a bad idea?

[ligfx]

Hey Vincent! How about http://localhost/v2/ (EDIT: added trailing slash)? That's a path mandated by the OCI Distribution Spec and k3d-registry-dockerd always returns HTTP 200.

I'm not too familiar with healthchecks, is this something that should be in the published image?

[vincentjorgensen]

After some trial and error, I learned that curl is not installed on the container, BUT wget is. So, this works:

services:
  registry:
  healthcheck:
      test: ["CMD", "wget", "-q", "localhost:5000/v2/", "-O", "/dev/null"]
      interval: 10s
      timeout: 3s
      retries: 3
      start_period: 10s
      start_interval: 1s

This is sufficient for my needs. Thank you!

[ligfx]

🥳 I'm going to keep this open, if you don't mind, as a reminder to add this to the actual image too.

[vincentjorgensen]

For the curious, this is my full docker compose file (jinja2 template syntax):

---
services:
  registry:
    container_name: k3d-dockerproxy
    environment:
      K3S_KUBECONFIG_OUTPUT: /output/kubeconfig.yaml
    healthcheck:
      interval: 10s
      retries: 3
      start_interval: 1s
      start_period: 10s
      test: ["CMD", "wget", "-q", "localhost:5000/v2/", "-O", "/dev/null"]
      timeout: 3s
    hostname: k3d-dockerproxy
    image: ligfx/k3d-registry-dockerd:{{ ligfx_ver }}
    init: true
    labels:
      app: k3d
      k3d.cluster: ""
      k3d.registry.host: ""
      k3d.registry.hostIP: 0.0.0.0
      k3d.role: registry
      k3s.registry.port.internal: 5000
    networks:
      default:
        ipv4_address: {{ registry_ip }}
    ports:
    - name: registry
      target: 5000
      host_ip: 0.0.0.0
      protocol: tcp
    privileged: true
    restart: unless-stopped
    security_opt:
    - label=disable
    tmpfs:
    - /run
    - /var/run
    userns_mode: host
    volumes:
    - /var/run/docker.sock:/var/run/docker.sock
networks:
  default:
    driver: bridge
    external: true
    name: {{ network }}
...

Edit: Figured out how to randomly assign an external port. :-)