Cobra Softwares Blog

Prerequisites

Before you begin:

• Have an Ubuntu 20.04 server.
• Create a Container Registry to store your Podman container images. This article uses Vultr Container Registry as an example, but the commands can be adapted to any registry by switching to the appropriate registry-specific variables.
• Access the server using SSH as a non-root user with sudo privileges.
• Update the server.

Install Podman

Podman is available in the default package repositories on Ubuntu 20.04. Follow the steps below to install Podman on your server using the APT package manager.

1. Update the server’s package index.
   console

   $ sudo apt update
   

2. Load the system release information.
   console

   $ source /etc/os-release
   

3. Add the official Podman repository to your server’s apt index.
   console

   $ echo "deb https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/xUbuntu_${VERSION_ID}/ /" | sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable.list
   

4. Import the repository’s GPG key.
   console

   $ curl -fsSL https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable/xUbuntu_${VERSION_ID}/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/libcontainers.gpg > /dev/null
   

5. Update the package index again.
   console

   $ sudo apt update
   

6. Install Podman.
   console

   $ sudo apt install podman -y
   

7. View the installed Podman version on your server.
   console

   $ podman --version
   

   Your output should be similar to the one below.

   podman version 3.4.2

Manage the Podman System Service

Podman operates with two system services: podman CLI and podman.socket. The podman CLI allows users to interact directly with Podman to manage containers, images, and pods. Meanwhile, podman.socket is a systemd socket file that provides remote API access for managing Podman, making it suitable for remote control and integration with development tools. You can also run Podman as a system service using podman.socket. Follow the steps below to manage and enable the Podman system service on your server.

1. Enable the Podman service to automatically start at system boot.
   console

   $ sudo systemctl enable podman.socket
   

2. Start the Podman service.
   console

   $ sudo systemctl start podman.socket
   

3. Stop the Podman service.
   console

   $ sudo systemctl stop podman.socket
   

4. Restart the Podman service.
   console

   $ sudo systemctl restart podman.socket
   

5. View the Podman service status and verify that it’s running.
   console

   $ sudo systemctl status podman.socket
   

   Output:

   ● podman.socket - Podman API Socket
        Loaded: loaded (/usr/lib/systemd/system/podman.socket; enabled; preset: enabled)
        Active: active (listening) since Mon 2024-08-26 12:07:01 UTC; 37s ago
      Triggers: ● podman.service
          Docs: man:podman-system-service(1)
        Listen: /run/podman/podman.sock (Stream)
        CGroup: /system.slice/podman.socket

Deploy Containerized Applications using Podman

Podman utilizes different image sources to pull container images from registries listed in the /etc/containers/registries.conf file. Follow the steps below to deploy an HTTP server application using the Nginx container image from Docker Hub.

1. Pull the Nginx container image from Docker Hub.
   console

   $ podman pull docker.io/nginx:alpine
   

   Output:

   Trying to pull docker.io/library/nginx:alpine...
   //...
   Writing manifest to image destination
   1ae23480369fa4139f6dec668d7a5a941b56ea174e9cf75e09771988fe621c95

2. List all container images available on the server.
   console

   $ podman images
   

   Verify that the Nginx container image is available in your output.

   REPOSITORY               TAG         IMAGE ID      CREATED      SIZE
   docker.io/library/nginx  alpine      1ae23480369f  6 weeks ago  45.1 MB

3. Run a new containerized application using the Nginx image.
   console

   $ podman run -d --name nginx-server -p 9090:80 docker.io/nginx:alpine
   

4. List all running Podman container processes.
   console

   $ podman ps
   

   Output:

   CONTAINER ID  IMAGE                           COMMAND               CREATED        STATUS        PORTS                 NAMES
   20628c4b7d0f  docker.io/library/nginx:alpine  nginx -g daemon o...  4 seconds ago  Up 4 seconds  0.0.0.0:9090->80/tcp  nginx-server

5. Test access to the container using the host port 9090.
   console

   $ curl http://localhost:9090
   

   Output:

   <!DOCTYPE html>
   <html>
   <head>
   <title>Welcome to nginx!</title>
   //.....

Log in to Vultr Container Registry

Podman supports custom registries like the Vultr Container Registry to build and store container images. Follow the steps below to create a Python application using FastAPI, build the container image, and push it to your Vultr Container Registry.

1. Access your Vultr Container Registry’s management panel to view the registry’s username and API key credentials.
2. Create a new environment variable to store your Vultr Container Registry name.
   console

   $ export VULTR_CONTAINER_REGISTRY_NAME=<enter the Vultr Container Registry name>
   

3. Create another environment variable to store the registry username.
   console

   $ export VULTR_CONTAINER_REGISTRY_USERNAME=<enter the Vultr Container Registry username>
   

4. Create a environment variable to store the registry’s API key.
   console

   $ export VULTR_CONTAINER_REGISTRY_API_KEY=<enter the Vultr Container Registry API key>
   

5. Log in to your Vultr Container Registry using the environment variable values.
   console

   $ sudo podman login sjc.vultrcr.com/$VULTR_CONTAINER_REGISTRY_NAME -u $VULTR_CONTAINER_REGISTRY_USERNAME -p $VULTR_CONTAINER_REGISTRY_API_KEY
   

   Replace sjc.vultrcr.com with the URL of the region where your VCR is hosted.

   Output:

   Login Succeeded!

6. Create a new Python application file app.py.
   console

   $ nano app.py
   

7. Add the following contents to the file.
   python

   from fastapi import FastAPI, Response
   import uvicorn
   
   app = FastAPI()
   
   @app.get("/")
   def hello():
       return Response(content="Hello from Vultr", media_type="text/plain")
   
   if __name__ == "__main__":
       uvicorn.run(app, host="0.0.0.0", port=5000)
   

   Save and close the file.

   The above FastAPI application initializes a new web server on port 5000 that displays a Hello from Vultr message when accessed.

8. Create a new Dockerfile configuration.
   console

   $ nano Dockerfile
   

9. Add the following contents to the file.
   dockerfile

   FROM python:3.12-slim
   WORKDIR /app
   COPY app.py /app
   RUN pip install fastapi uvicorn
   EXPOSE 5000
   CMD ["python", "app.py"]
   

   Save and close the file.

   The above Dockerfile creates a Python 3.12 environment, installs fastapi and uvicorn, and runs a web server on port 5000 using the app.py file.

10. Build the container image with all files in your working directory.
    console

    $ podman build -t python-fastapi-app .
    

    Output:

    //...
    Successfully tagged localhost/python-fastapi-app:latest
    8f00b7a023da93ce714c41ab817be66913385f8c8583b4c38e59a35e53af0037

11. Tag the container image with your Vultr Container Registry’s name.
    console

    $ podman tag python-fastapi-app sjc.vultrcr.com/$VULTR_CONTAINER_REGISTRY_NAME/python-fastapi-app:v1
    

    Replace sjc.vultrcr.com with the URL of the region where your VCR is hosted.

12. List all container images on your server and verify that the tagged image is available.
    console

    $ podman images
    

    Output:

    REPOSITORY                               TAG         IMAGE ID      CREATED         SIZE
    sjc.vultrcr.com/demo/python-fastapi-app  v1          8f00b7a023da  30 seconds ago  217 MB
    localhost/python-fastapi-app             latest      8f00b7a023da  30 seconds ago  217 MB
    docker.io/library/nginx                  alpine      1ae23480369f  6 weeks ago     45.1 MB
    docker.io/library/python                 3.12-slim   8d6f9eba56c9  11 days ago     135 MB

13. Push the image to your Vultr Container Registry.
    console

    $ podman push sjc.vultrcr.com/$VULTR_CONTAINER_REGISTRY_NAME/python-fastapi-app:v1
    

    Replace sjc.vultrcr.com with the URL of the region where your VCR is hosted.

    Output:

    //...
    Writing manifest to image destination

14. Deploy a new containerized application using your Vultr Container Registry image.
    console

    $ podman run -d --name demo-app -p 5000:5000 sjc.vultrcr.com/$VULTR_CONTAINER_REGISTRY_NAME/python-fastapi-app:v1
    

15. Test access to the application using Curl on the host port 5000.
    console

    $ curl http://localhost:5000
    

    Output:

    Hello from Vultr

Conclusion

You have successfully installed Podman on your Ubuntu 20.04 server and deployed containerized applications. Podman allows you to build, store, and manage containers on your server.