Lesson 02: Docker on Pi5

2.1 Installing Docker on Raspberry Pi 5

Installing Docker on Raspberry Pi 5

Follow these steps to install Docker on your Raspberry Pi 5 using Docker's official apt repository:

Update and install prerequisites:


sudo apt-get update
sudo apt-get install ca-certificates curl

Add Docker's official GPG key:


sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

Add Docker repository to apt sources:


echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

Install Docker packages:


sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

After completing these steps, Docker will be installed and ready to use on your Raspberry Pi 5.

2.2 Changing the Docker Root Direction

Relocating the Docker root directory on a Raspberry Pi 5 involves changing the directory where Docker stores all its data, including images, containers, volumes, and configurations. Docker uses /var/lib/docker as the root directory by default. If you want to move this directory to a different location, follow these steps:

Step 1: Stop the Docker Service

First, stop the Docker service to ensure no Docker processes are running while you move the data.

sudo systemctl stop docker

Step 2: Create the New Docker Directory

Create the new directory where you want Docker to store its data. For example, if you want to move it to /mnt/docker-data, you can create this directory:

sudo mkdir -p /ssd/docker

Step 3: Move the Existing Docker Data

Now, move the existing Docker data from /var/lib/docker to the new directory:

sudo rsync -aP /var/lib/docker/ /ssd/docker/

The rsync command is used here to ensure that all files are copied correctly and that the ownership and permissions are preserved.

Step 4: Update Docker Configuration

Tell Docker to use the new directory. To do this, create or edit the Docker daemon configuration file:

sudo nano /etc/docker/daemon.json

Add or modify the following line to specify the new directory:


{
    "data-root": "/ssd/docker"
}

Step 5: Start the Docker Service

Now that Docker's configuration has been updated restart the Docker service:


sudo systemctl start docker

Step 6: Verify the Change

To verify that Docker is now using the new directory, you can run:


docker info | grep "Docker Root Dir"
 Docker Root Dir: /ssd/docker

This command should show the new directory, confirming that Docker uses it correctly.

Step 7: Clean Up (Optional)

If everything is working correctly, and you're confident that the data was successfully moved, you can delete the old Docker data directory to free up space:


sudo rm -rf /var/lib/docker

You have successfully relocated the Docker root directory on your Raspberry Pi 5. Docker should now store all its data in the new directory you specified. This can be particularly useful if you're running low on space on the default filesystem or have a faster or larger storage option.