Accessing a Docker Host with Portainer: Privileged Container Guide

A simple guide to accessing the docker host from your Portainer instance

In this article, I will show you how to access the host machine from a Portainer instance.

Assumptions

• Familiarity with Docker

• Familiarity with Portainer

• Docker is installed on your machine

Introduction

Portainer is management software for containers. It's packed with amazing features that make working with Docker seamless. Portainer itself runs as a Docker container. It connects to the underlying Docker host using Docker mounts. Below is a Docker Compose file showing a Portainer container deployment.

volumes:
  portainer-data:

services:
  portainer:
    container_name: portainer
    image: "docker.io/portainer/portainer-ce:2.21.0-rc2-alpine"
    ports:
      - "9000:9000"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - portainer-data:/data
    restart: always

After saving and running this compose file, a Portainer instance will be accessible at http://localhost:9000.

Lets get to it then!

Portainer has a feature called stacks that lets you define a compose project and deploy it to your Docker host (server) directly from the Portainer web interface.

Let's create a new stack with the following Docker Compose content. Remember to add a name of your stack.

services:
  chroot_service:
    image: busybox
    container_name: chroot_service
    privileged: true
    network_mode: host
    pid: host
    ipc: host
    volumes:
      - /:/host
    tty: true  # Enable TTY
    stdin_open: true  # Keep stdin open
    command: chroot /host

Now save and run this stack. You will see the following container running.

Select the container chroot_service and open an interactive console in the Portainer instance. Be sure to select the /bin/sh type since we are using busybox image.

In the console, run the chroot command into the host directory. Voila! you are in the host system console as a root user.

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