How to create custom image using RHEL-ImageBuilder.
Prerequisites:
You must be connected to a RHEL VM. The VM for image builder must be running and subscribed to Red Hat Subscription Manager (RHSM) or Red Hat Satellite.
Procedure:
Install the image builder and other necessary packages by running below commands:
osbuild-composer - supported from RHEL 8.3 onward composer-cli cockpit-composer bash-completion
Command:
# dnf install osbuild-composer composer-cli cockpit-composer bash-completion
Enable image builder to start after each reboot:
# systemctl enable --now osbuild-composer.socket systemctl enable --now cockpit.socket
Overriding a system repository
Prerequisites: You have a custom repository that is accessible from the host system.
Procedure: Create a directory where you want to store your repository overrides:
# sudo mkdir -p /etc/osbuild-composer/repositories
Copy the file for your distribution from /usr/share/osbuild-composer/ and modify its content.For RHEL 8.7, use /etc/osbuild-composer/repositories/rhel-87.json. Now restart the osbuild-composer.service
# sudo systemctl restart osbuild-composer.service
Setup to create Image using Image Builder is completed.
Create Image using command line
The workflow for the command-line interface can be summarized as follows:
Export (save) the blueprint definition to a plain text file Edit this file in a text editor Import (push) the blueprint text file back into image builder Run a compose to build an image from the blueprint Export the image file to download it
Create file with extension .toml. In this repo case we created FIRSTIMAGE-BULEPRINT.toml Now Push (import) the blueprint:
# composer-cli blueprints push BLUEPRINT-NAME.toml
Verify that the blueprint has been pushed and exists:
# composer-cli blueprints list you will able to see your Buleprint.
Display the blueprint configuration you have just added:
# composer-cli blueprints show FIRSTIMAGE
Check whether the components and versions listed in the blueprint and their dependencies are valid:
# composer-cli blueprints depsolve FIRSTIMAGE
If image builder is unable to depsolve a package from your custom repositories, follow the steps:
Remove the osbuild-composer cache:
# sudo rm -rf /var/cache/osbuild-composer/*
# sudo systemctl restart osbuild-composer
Creating a system image with image builder in the command-line interface
Procedure: Start the compose
# composer-cli compose start BLUEPRINT-NAME IMAGE-TYPE
Composing images from blueprints
# composer-cli compose types
Currently this are the valid types availables :
Now run the below command to create iso image using our Blueprint
# composer-cli compose start FIRSTIMAGE image-installer output of above command: Compose c1e507cb-ffdf-4564-842a-89e3c2ade65d added to the queue where c1e507cb-ffdf-4564-842a-89e3c2ade65d is the unique UUID of the image creation
After running the command Compose added in the queue you can check the status by running below command.
# composer-cli compose status
To check Logs
# composer-cli compose log <build_id>
To download the created image
# composer-cli compose image COMPOSE-UUID
After downloading the image you can test the image by creating the virtual machine in oracle virtual box. The image which is created contains only limited required packages, if you want to add some custom packages you need to add it in blueprint while creating the image.
