Chapter 7. Configuring the discovery image
The Assisted Installer uses an initial image to run an agent that performs hardware and network validations before attempting to install OpenShift Container Platform. You can use Ignition to customize the discovery image.
Modifications to the discovery image will not persist in the system.
7.1. Creating an Ignition configuration file Copy linkLink copied to clipboard!
Ignition is a low-level system configuration utility, which is part of the temporary initial root filesystem, the initramfs. When Ignition runs on the first boot, it finds configuration data in the Ignition configuration file and applies it to the host before switch_root
is called to pivot to the host’s root filesystem.
Ignition uses a JSON configuration specification file to represent the set of changes that occur on the first boot.
Ignition versions newer than 3.2 are not supported, and will raise an error.
Procedure
Create an Ignition file and specify the configuration specification version:
vim ~/ignition.conf
$ vim ~/ignition.conf
Copy to Clipboard Copied! Toggle word wrap Toggle overflow { "ignition": { "version": "3.1.0" } }
{ "ignition": { "version": "3.1.0" } }
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Add configuration data to the Ignition file. For example, add a password to the
core
user.Generate a password hash:
openssl passwd -6
$ openssl passwd -6
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Add the generated password hash to the
core
user:Copy to Clipboard Copied! Toggle word wrap Toggle overflow
Save the Ignition file and export it to the
IGNITION_FILE
variable:export IGNITION_FILE=~/ignition.conf
$ export IGNITION_FILE=~/ignition.conf
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
7.2. Modifying the discovery image with Ignition Copy linkLink copied to clipboard!
Once you create an Ignition configuration file, you can modify the discovery image by patching the infrastructure environment using the Assisted Installer API.
Prerequisites
- If you used the web console to create the cluster, you have set up the API authentication.
-
You have an infrastructure environment and you have exported the infrastructure environment
id
to theINFRA_ENV_ID
variable. -
You have a valid Ignition file and have exported the file name as
$IGNITION_FILE
.
Procedure
Create an
ignition_config_override
JSON object and redirect it to a file:jq -n \ --arg IGNITION "$(jq -c . $IGNITION_FILE)" \ '{ignition_config_override: $IGNITION}' \ > discovery_ignition.json
$ jq -n \ --arg IGNITION "$(jq -c . $IGNITION_FILE)" \ '{ignition_config_override: $IGNITION}' \ > discovery_ignition.json
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Refresh the API token:
source refresh-token
$ source refresh-token
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Patch the infrastructure environment:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow The
ignition_config_override
object references the Ignition file.- Download the updated discovery image.