Docker Inside Docker (DinD) Guide 🚀

Overview

This guide explains how to set up Docker inside Docker (DinD). This approach is useful for CI/CD pipelines, enabling Docker commands to be executed within a Docker container.

Prerequisites 📋

• Docker installed on the host machine
• Basic knowledge of Docker commands
• Docker Compose (optional, for easier orchestration)

Step-by-Step Guide 🛠️

Step 1: Install Docker 🐳

If Docker is not already installed on your host machine, follow these steps:

1. Update the package database:

   sudo apt-get update
   

2. Install prerequisites:

   sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
   

3. Add Docker’s official GPG key:

   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
   
   

4. Add Docker’s repository:

   sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
   
   

5. Install Docker CE:

   sudo apt-get update
   sudo apt-get install docker-ce
   
   

6. Verify Docker installation:

   docker --version
   
   

Step 2: Create a Dockerfile for DinD 📄

Create a Dockerfile that uses the official Docker-in-Docker image:

# Dockerfile
FROM docker:20.10.7-dind

# Optional: Install any additional packages
RUN apk add --no-cache git

# Optional: Create a working directory
WORKDIR /app

# Optional: Copy application files
COPY . /app

# Entry point for the Docker container
CMD ["sh"]

Step 3: Build the Docker Image 🏗️

Build the Docker image from the Dockerfile:

docker build -t my-dind-image .

Step 4: Run the DinD Container ▶️

Run a container using the DinD image with necessary Docker daemon options:

docker run --privileged --name my-dind-container -d docker:20.10.7-dind

--privileged grants the container extended privileges. --name assigns a name to the container. -d runs the container in detached mode.

Step 5: Interact with Docker Inside the Container 🐙

1. Access the running DinD container:

   docker exec -it my-dind-container sh
   

2. Verify Docker daemon is running inside the container:

   docker info
   

3. Run Docker commands inside the container:

   docker run hello-world
   

Step 6: Clean Up 🧹

To stop and remove the DinD container:

docker stop my-dind-container
docker rm my-dind-container

To remove the Docker image:

docker rmi my-dind-image

Conclusion 🎉

You have successfully set up Docker inside Docker (DinD). This configuration is ideal for CI/CD pipelines and allows you to run Docker commands within a Docker container.