Bob Explores Linux Containers with Podman on AlmaLinux

Bob’s next challenge was to dive into Linux containers using Podman, a daemonless container engine built for running, managing, and building containers. Containers allow for lightweight, portable applications, and Bob knew mastering them would future-proof his sysadmin skills.

“Containers are the future of IT—let’s get started with Podman!” Bob said enthusiastically.

Chapter Outline: “Bob Explores Linux Containers with Podman”

1. Introduction: What Are Containers?

   • Overview of containerization.
   • Podman vs. Docker.

2. Installing and Setting Up Podman

   • Installing Podman on AlmaLinux.
   • Configuring Podman for rootless operation.

3. Running and Managing Containers

   • Pulling container images.
   • Running and stopping containers.

4. Building Custom Container Images

   • Writing a Dockerfile.
   • Building images with Podman.

5. Using Pods for Multi-Container Applications

   • Understanding pods in Podman.
   • Creating and managing pods.

6. Persisting Data with Volumes

   • Creating and attaching volumes.
   • Backing up container data.

7. Networking and Port Management

   • Exposing ports for containerized services.
   • Configuring container networks.

8. Automating Containers with Systemd

   • Generating Systemd service files for containers.
   • Managing containers as services.

9. Conclusion: Bob Reflects on Container Mastery

Part 1: Introduction: What Are Containers?

Bob learned that containers are lightweight, portable environments for running applications. Unlike virtual machines, containers share the host kernel, making them faster to start and use fewer resources.

Why Podman?

• Daemonless: Runs without a central daemon, unlike Docker.
• Rootless Mode: Allows non-root users to run containers securely.
• Docker-Compatible: Supports Dockerfiles and images.

“With Podman, I get the power of Docker without the baggage!” Bob said.

Part 2: Installing and Setting Up Podman

Step 1: Installing Podman

• Install Podman:

  sudo dnf install -y podman
  

• Verify the installation:

  podman --version
  

Step 2: Configuring Rootless Podman

Bob configured Podman to run without root privileges for added security:

sudo sysctl user.max_user_namespaces=28633

• Log in as a regular user and test Podman:

  podman info
  

“Podman is ready to go—time to run my first container!” Bob said.

Part 3: Running and Managing Containers

Step 1: Pulling Container Images

• Search for an image:

  podman search nginx
  

• Pull the official nginx image:

  podman pull docker.io/library/nginx
  

Step 2: Running a Container

• Run the nginx container:

  podman run -d --name webserver -p 8080:80 nginx
  

• Check the running container:

  podman ps
  

• Access the containerized web server in a browser:

  http://<server-ip>:8080
  

Step 3: Stopping and Removing Containers

• Stop the container:

  podman stop webserver
  

• Remove the container:

  podman rm webserver
  

“Containers make deploying services quick and easy!” Bob said.

Part 4: Building Custom Container Images

Step 1: Writing a Dockerfile

Bob created a Dockerfile to build a custom nginx image:

nano Dockerfile

• Example Dockerfile content:

  FROM nginx:latest
  COPY index.html /usr/share/nginx/html/index.html
  

Step 2: Building the Image

• Build the image with Podman:

  podman build -t custom-nginx .
  

• Verify the image:

  podman images
  

“With custom images, I can tailor containers to my exact needs!” Bob said.

Part 5: Using Pods for Multi-Container Applications

Step 1: Understanding Pods

Bob learned that a pod groups multiple containers to share networking and storage.

Step 2: Creating and Managing Pods

• Create a pod:

  podman pod create --name mypod -p 8080:80
  

• Add containers to the pod:

  podman run -d --pod mypod nginx
  podman run -d --pod mypod redis
  

• List pod containers:

  podman ps --pod
  

“Pods make managing multi-container apps a breeze!” Bob said.

Part 6: Persisting Data with Volumes

Step 1: Creating a Volume

• Create a volume:

  podman volume create nginx-data
  

Step 2: Attaching the Volume

• Run a container with the volume:

  podman run -d --name webserver -v nginx-data:/usr/share/nginx/html nginx
  

Step 3: Backing Up Container Data

• Back up the volume:

  podman volume inspect nginx-data
  podman run --rm -v nginx-data:/data -v $(pwd):/backup busybox tar czvf /backup/nginx-data-backup.tar.gz /data
  

“Volumes keep my data safe even if containers are recreated!” Bob noted.

Part 7: Networking and Port Management

Exposing Ports

Bob exposed a container’s ports to make it accessible from outside:

podman run -d --name webserver -p 8080:80 nginx

Configuring Container Networks

• List networks:

  podman network ls
  

• Create a custom network:

  podman network create mynetwork
  

• Run a container on the custom network:

  podman run -d --name webserver --network mynetwork nginx
  

Part 8: Automating Containers with Systemd

Step 1: Generating Systemd Service Files

• Generate a Systemd unit file for a container:

  podman generate systemd --name webserver --files
  

• Copy the generated file to the system directory:

  sudo cp container-webserver.service /etc/systemd/system/
  

Step 2: Managing Containers as Services

• Enable and start the service:

  sudo systemctl enable container-webserver
  sudo systemctl start container-webserver
  

“With Systemd, I can manage containers just like regular services!” Bob said.

Conclusion: Bob Reflects on Container Mastery

Bob successfully learned to deploy, manage, and automate containers using Podman. With lightweight and portable containers, he was confident his AlmaLinux server was future-proofed for modern applications.

Next, Bob plans to explore Configuring Advanced Monitoring with Prometheus and Grafana on AlmaLinux.