065 Run a Service Inside a Container

Tech Tutorial: Manage Containers on RHEL #

Introduction #

In this tutorial, we’ll cover how to manage and run services inside containers specifically using tools and commands applicable in Red Hat Enterprise Linux (RHEL). This knowledge is particularly relevant for those preparing for the Red Hat Certified System Administrator (RHCSA) exam, which includes an objective on running services within containers.

Containers are lightweight, provide a consistent environment for applications, and are isolated from the host system. They make it easier to manage dependencies, ensure consistency across multiple development and production environments, and scale applications efficiently.

We will use Podman, a daemonless container engine for developing, managing, and running OCI Containers on your Linux System. Podman is included in the default RHEL 8 and RHEL 9 repositories and is a core part of the RHCSA exam objectives related to containers.

Prerequisites #

  • A running instance of RHEL 8 or RHEL 9.
  • Root or sudo privileges.
  • Basic familiarity with command-line interface and Linux environment.

Step-by-Step Guide #

Step 1: Install Podman #

First, ensure that your system is updated and then install Podman.

sudo dnf update -y
sudo dnf install -y podman

Step 2: Search for Container Images #

Before you can run a service inside a container, you need an appropriate image. Let’s say we want to run an Nginx server. First, search for Nginx images:

podman search nginx

Step 3: Pull the Container Image #

Pull the official Nginx image from the registry:

podman pull nginx

Step 4: Run the Nginx Service in a Container #

Now, run the Nginx service inside a container:

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

This command does the following:

  • --name mynginx: Names the container ‘mynginx’.
  • -d: Runs the container in detached mode.
  • -p 8080:80: Maps port 80 of the container to port 8080 on the host.

Step 5: Verify the Container is Running #

Check that the container is running and the Nginx service is accessible:

podman ps

You should see your Nginx container running. You can also access it through the browser or using curl:

curl http://localhost:8080

Step 6: Managing the Container #

To stop the container, use:

podman stop mynginx

To start the container again, use:

podman start mynginx

To remove the container when you are done, use:

podman rm mynginx

Detailed Code Examples #

Let’s go a bit further and see how to use a custom Nginx configuration within our container. For this, we need a custom configuration file on the host.

  1. Create a directory for custom configurations:
mkdir -p ~/custom-nginx
cd ~/custom-nginx

  1. Create a new nginx.conf file and modify as needed.

  2. Run the container using the custom configuration:

podman run --name custom-nginx -v ~/custom-nginx/nginx.conf:/etc/nginx/nginx.conf:Z -d -p 8080:80 nginx

The -v option mounts the custom configuration file inside the container.

Conclusion #

In this tutorial, you’ve learned how to install Podman, search for, pull, and run a Docker image as a container service in RHEL. We also covered how to manage the lifecycle of containers and how to use custom configurations. This knowledge will be beneficial not only for the RHCSA exam but also for real-world applications where containerization is increasingly becoming a standard practice.