Share docker socket to http rest with some filtering

I will share socket files to http with forward tool, https://github.com/worldline-go/forward which I programmed.

This tool listening http request and forwarding to the socket with some method filtering.

So lets download or run in docker:

To download visit the release page

# scratch version
docker pull ghcr.io/worldline-go/forward:v0.1.2
# alpine version
docker pull ghcr.io/worldline-go/forward:v0.1.2-alpine

This tool asking you a command parameter to show location of the socket file and redirection path and some filtering methods.

In here, I will redirect all /docker/* requests to the docker.sock file. And I will disabled some method, so without any filtering methods all methods is works.

Using - begining on the method name is disabling:

-s /docker.sock:/docker/:-POST,-PUT,-DELETE,-PATCH

export socket to HTTP
version: 0.1.2 commit: b8e86c7 buildDate:2022-06-29T10:46:25Z

Usage:
  forward [flags]

Flags:
  -h, --help                 help for forward
  -H, --host string          Host to listen on, default: 0.0.0.0:8080 (default "0.0.0.0:8080")
  -s, --socket stringArray   Socket to export: /var/run/docker.sock:/docker/:*,-POST,-PUT,-DELETE
  -v, --version              version for forward

Lets run

docker run --rm -p 8080:8080 -v /var/run/docker.sock:/docker.sock ghcr.io/worldline-go/forward:v0.1.2 -s /docker.sock:/docker/:-POST,-PUT,-DELETE,-PATCH

Now call http service, (check this document for detail)

curl http://localhost:8080/docker/containers/json

I shared to the /docker path so I called with /docker prefix but this is for just demo not need to set any path.

---

Now, we can use this tool for in traefik.

Traefik is a proxy tool and in swarm mode it is need a docker.sock communication to find services's information.

We can mount docker.sock to Traefik and solve communication but there is one point. In the swarm's worker nodes docker.sock cannot reach to the swarm-api (default). We can fix this communication to run forward tool as service and set Traefik to the our service to communicate with docker socket.

Forward service

forward-docker:
  image: ghcr.io/worldline-go/forward:v0.1.2
  command: "-s /var/run/docker.sock::-POST,-PUT,-PATCH,-DELETE"
  deploy:
    mode: global
    # Just works in manager nodes for swarm API
    placement:
      constraints:
        - "node.role==manager"
  volumes:
    - /var/run/docker.sock:/var/run/docker.sock
  networks:
    - proxy

In traefik's static configuration change enpoint

providers:
  docker:
    # endpoint: "unix///var/run/docker.sock"
    endpoint: "tcp://forward-docker:8080"

Now you can replicate your Traefik in the all nodes of the swarm.