Docker

Docker is a tool that makes it easy to run applications in isolated environments called containers.

Think of it like this:
📦 A container is like a “portable box” that has everything an app needs to run (code, libraries, dependencies).
🚢 Docker is the system that builds, runs, and manages these boxes.

Why use Docker?

✅ Works everywhere – Runs the same on your PC, server, or cloud.
✅ No “it works on my machine” issues – Everything is inside the container.
✅ Lightweight & fast – Uses less space than virtual machines.

• Stop and Remove the Old Container:

sudo docker stop remark42 && sudo docker rm remark42

• Recreate and Start the Container with the Updated docker-compose.yml:

sudo docker-compose up -d

• Check if the New Container is Running:

sudo docker ps

Installation

I chose to go with the docker engine rather than Docker Desktop for Linux because I’m using this to deploy a server and I don’t need Kubernetes and all that extra stuff. Additionally, Docker Desktop for Linux runs in a VM, while the engine runs locally (I think).

Using the apt Repository

Run the following command to uninstall all conflicting packages:

for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do sudo apt-get remove $pkg; done

1. Set up Docker’s apt repository.

   # Add Docker's official GPG key:
   sudo apt-get update
   sudo apt-get install ca-certificates curl
   sudo install -m 0755 -d /etc/apt/keyrings
   sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
   sudo chmod a+r /etc/apt/keyrings/docker.asc
    
   # Add the repository to Apt sources:
   echo \
     "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
     $(. /etc/os-release && echo "${UBUNTU_CODENAME:-$VERSION_CODENAME}") stable" | \
     sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
   sudo apt-get update

2. Install the Docker packages.

   Latest Specific version

   ---

   To install the latest version, run:

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

---

3. Verify that the installation is successful by running the hello-world image:

   sudo docker run hello-world

¹

Docker Compose

Installation

1. Update the package index, and install the latest version of Docker Compose:

   • For Ubuntu and Debian, run:

     $ sudo apt-get updatesudo docker stop remark42

sudo docker rm remark42

    $ sudo apt-get install docker-compose-plugin
    ```
    
- For RPM-based distributions, run:
    
    ```console
    $ sudo yum update
    $ sudo yum install docker-compose-plugin
    ```
    

2. Verify that Docker Compose is installed correctly by checking the version.

```console
$ docker compose version
```

Expected output:

```text
Docker Compose version vN.N.N
```

Where `vN.N.N` is placeholder text standing in for the latest version.

Update Docker Compose

To update the Docker Compose plugin, run the following commands:

• For Ubuntu and Debian, run:

sudo apt-get update
sudo apt-get install docker-compose-plugin

• For RPM-based distributions, run:

sudo yum update
sudo yum install docker-compose-plugin

Footnotes

1. https://docs.docker.com/engine/install/ubuntu/ ↩