Docker-proxy-ACL-Alpine

Lightweight container running a restricted Docker unix socket proxy

Image size	RAM usage	CPU usage
5.82MB	10MB	Low

Why

• A better version than titpetric/docker-proxy-acl
  • 6MB instead of 450MB Docker image
  • Options can be changed with the command line argument
  • Emojis
  • More checks
• No need to run with --privileged although you bind mount the docker socket
• No networking, just unix socket files

Exposing /var/run/docker.sock to a Docker container requiring it (such as netdata) involves security concerns and the container should be limited in what it can do with docker.sock.

You can enable an endpoint with the -a argument. Currently supported endpoints are:

• containers: opens access to /containers/json and /containers/{name}/json
• images: opens access to /images/json , /images/{name}/json and /images/{name}/history
• networks: opens access to /networks and /networks/{name}
• volumes: opens access to /volumes and /volumes/{name}
• services: opens access to /services and /services/{id}
• tasks: opens access to /tasks and /tasks/{name}
• events: opens access to /events
• info: opens access to /info
• version: opens access to /version
• ping: opens access to /_ping
• Untested endpoints:
  • events
  • auth
  • secrets
  • build
  • commit
  • configs
  • distribution
  • exec
  • nodes
  • plugins
  • session
  • swarm
  • system

To combine arguments, repeat them like this: -a info -a version

Setup

The following is in example for netdata, such that it can resolve the container names found in the cgroups filesystem.

docker run -d --net=none \
-v /var/run/docker.sock:/var/run/docker.sock \
-v /yourpath:/tmp/docker-proxy-acl \
qmcgaw/docker-proxy-acl-alpine -a containers

A new socket file is hence created at /yourpath/docker.sock with only the /containers/json and /containers/{name}/json endpoints allowed.

This socket file can then be passed to the netdata container, with an additional option like this:

-v /yourpath/docker.sock:/var/run/docker.sock

You can also use docker-compose:

version: '3'
services:
  docker-proxy:
    build: .
    image: qmcgaw/docker-proxy-acl-alpine
    container_name: docker-proxy
    volumes:
      - /yourpath/docker-proxy-acl:/tmp/docker-proxy-acl
      - /var/run/docker.sock:/var/run/docker.sock
    command: -a containers
    network_mode: none
    restart: always

TODOs

• Change to another router
• Healthcheck
• Non root user
• Title icon