OpenShift Hands-On Lab - Working with Image Registries, Tagging and Saving an Image using Podman

📝Introduction

In this lab, we will configure Podman to use 2 new registries running on the local system. In addition to this, a custom version of an image will be searched for and pulled to the local system. Also, we will explore podman image tagging, modifying a container, saving an image, and pushing an image to a repository.

These are the objectives of this lab:

Configure New Local Registries
Configure the Insecure Registry
Pull a Custom Image to the System
Modify the Existing Containers Default Web Page
Commit the Changes to a New Image and Tag the Image
Create a .tar Archive of the New Image
Publish the New Image to a Local Registry

📝Log in to the AWS Management Console

Using your credentials, make sure you're using the right Region. In my case, I am using AWS as my cloud provider and chose us-east-1. However, for this hands-on lab, you can select any cloud provider to create your Linux server VMs (I am using a Red Hat Enterprise Linux 8.7 distro) and Podman 3.0.1 (Link to how to install Podman)

📌Note: You must create the AWS Access Key and AWS Secret Access Key and configure the AWS CLI in the terminal to use it.

You can use link1 and link2 for it.

📝Configure New Local Registries

Use superuser privilege to edit the file:

 sudo vim /etc/containers/registries.conf

Scroll down to the registries.search section.
Within the brackets next to registries =, type 'localhost:5000' and 'localhost:5001' separated by a comma (Remember to pushi to enter insert mode).

📝Configure the Insecure Registry

Scroll down to the registries.insecure section.
Within the brackets next to registries =, type 'localhost:5001'.
Save and quit the file by pressing Escape followed by :wq.

📌Note: When copying and pasting code into Vim from the lab guide, first enter :set paste (and then i to enter insert mode) to avoid adding unnecessary spaces and hashes. To save and quit the file, press Escape followed by :wq. To exit the file without saving, press Escape followed by :q!.
Log in to the secure registry on port 5000:
```
 podman login localhost:5000
```
Under username and password, enter your credentials.

📝Pull a Custom Image to the System

Find the llama-web image:
```
 podman search llama-web
```
Find the tags associated with llama-web image on localhost:5000 (The localhost registry and image were previously created and configured for demo purposes. You can use this link to explain how to create and configure):
```
 skopeo inspect docker://<IMAGE_NAME> | less
```
📌Note: Skopeo is a tool for manipulating, inspecting, signing, and transferring container images and image repositories on Linux® systems.
Press Escape followed by :q to exit.
Use the v1.1 tag to pull the image:
```
 podman pull <IMAGE_NAME>:v1.1
```
Clear your screen:
```
 clear
```
View the pulled image:
```
 podman images
```

📝Modify the Existing Containers Default Web Page

Verify the container is running:
```
 podman ps -a
```
Check the default web page:
```
 curl localhost:8080
```
Connect to the container:
```
 podman exec -it web-1 bash
```

Change the default web page:

 echo "Demo Tagging and Saving an Image using Podman" > /usr/share/nginx/html/index.html

Exit out of the container:
```
 exit
```
Verify the change was successful:
```
 curl localhost:8080
```

📝Commit the Changes to a New Image and Tag the Image

Commit the changes to a new image:

 podman commit web-1 localhost:5000/llama-rama-web

Verify the changes have been committed:
```
 podman images
```
Clear your screen:
```
 clear
```
View the image list:
```
 podman images
```

Tag the new image as v1.0:

 podman tag <IMAGE_NAME> <IMAGE_NAME>:v1.0

View the image list to verify the tag:
```
 podman images
```
clear your screen.

📝Create a .tar Archive of the New Image

View the image list:
```
 podman images
```

Create a .tar archive of the new image named llama-rama-web.tar:

 podman save -o llama-rama-web.tar localhost:5000/llama-rama-web:v1.0

Confirm the .tar file exists:
```
 ls -l llama-rama-web.tar
```
clear your screen.

📝Publish the New Image to a Local Registry

Log in to the registry:
```
 podman login localhost:5000
```
Use your credentials for the Username and Password.
View the image list:
```
 podman images
```
Push the llama-rama-web image with the v1.0 tag to the local registry:
```
 podman push <IMAGE_NAME>:v1.0 <IMAGE_NAME>:v1.0
```
clear your screen.
Verify the image was successfully pushed:
```
 podman search llama-rama-web
```

📌Note - At the end of each hands-on Lab, always clean up all previous resources created to avoid being charged if you used a Cloud Provider to provision them.

Congratulations — you have completed this hands-on lab covering the basics of Working with Image Registries, Tagging and Saving an Image using Podman.

Thank you for reading. I hope you understood and learned something helpful from my blog.

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