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Chapter 3. Managing repositories

3.1. Image Builder default system repositories

The osbuild-composer backend does not inherit the system repositories located in the /etc/yum.repos.d/ directory. Instead, it has its own set of official repositories defined in the /usr/share/osbuild-composer/repositories directory. To override the official repositories, you must define overrides in /etc/osbuild-composer/repositories. This directory is for user defined overrides and the files located here take precedence over those in the /usr directory.

The configuration files are not in the usual DNF repository format known from the files in /etc/yum.repos.d/. Instead, they are simple JSON files.

3.2. Overriding a system repository

You can configure a repository override in the /etc/osbuild-composer/repositories directory by following these steps.

Note

Prior to RHEL 8.5 release, the name of the repository overrides is rhel-8.json. Starting from RHEL 8.5, the names also respect the minor version: rhel-84.json, rhel-85.json, and so on.

Prerequisites

  • You have a custom repository that is accessible from the host system

Procedure

  1. Create a directory that contains the repository overrides you want to use: 

    $ sudo mkdir -p /etc/osbuild-composer/repositories

  2. Create a JSON file with the following structure, for example: 

    {
    "<ARCH>": [
        {
            "name": "baseos",
            "metalink": "",
            "baseurl": "http://mirror.example.com/composes/released/RHEL-8/8.2.0/BaseOS/x86_64/os/",
            "mirrorlist": "",
            "gpgkey": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n\n (...)",
            "check_gpg": true,
            "metadata_expire": "",
        }
    ]
}

    Specify only one of the following attributes: metalink, mirrorlist, or baseurl. The remaining fields are optional.

  3. Save the file using a name corresponding to your RHEL version, for example: 

    /etc/osbuild-composer/repositories/rhel-84.json
/etc/osbuild-composer/repositories/rhel-85.json
/etc/osbuild-composer/repositories/rhel-90.json

    Alternatively, you can copy the file for your distribution from /usr/share/osbuild-composer/ and modify its content.

  4. Copy the repository file to the directory you created. 

    $  cp /usr/share/osbuild-composer/repositories/rhel-version.json /etc/osbuild-composer/repositories/

    Replace rhel-version.json with your RHEL version, for example: rhel-85.json

  5. Using the editor of your choice, edit the baseurl paths in the rhel-85.json file. For example: 

    $  vi etc/osbuild-composer/repositories/rhel-85.json

As a result, the repository points to the correct URLs which are copied from the /etc/yum.repos.d/redhat.repo file.

3.3. Overriding a system repository with support for subscriptions

osbuild-composer service can use system subscriptions that are defined in the /etc/yum.repos.d/redhat.repo file. To use a system subscription in osbuild-composer, you need to define a repository override which has:

  • The same baseurl as the repository defined in /etc/yum.repos.d/redhat.repo.
  • The value of ”rhsm”: true defined in the JSON object.

Prerequisites

Procedure

  1. Get the baseurl from the /etc/yum.repos.d/redhat.repo file: 

    [AppStream]
name = AppStream mirror example
baseurl = https://mirror.example.com/RHEL-8/8.5.0/AppStream/x86_64/os/
enabled = 1
gpgcheck = 0
sslverify = 1
sslcacert = /etc/pki/ca1/ca.crt
sslclientkey = /etc/pki/ca1/client.key
sslclientcert = /etc/pki/ca1/client.crt
metadata_expire = 86400
enabled_metadata = 0

  2. Configure the repository override to use the same baseurl and set rhsm to true: 

    {
    "x86_64": [
        {
            "name": "AppStream mirror example",
            "baseurl": "https://mirror.example.com/RHEL-8/8.5.0/AppStream/x86_64/os/",
            "gpgkey": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n\n (...)",
            "check_gpg": true,
            "rhsm": true
        }
    ]
}
Note

osbuild-composer does not automatically use repositories defined in /etc/yum.repos.d/. You need to manually specify them either as a system repository override or as an additional source using composer-cli. System repository overrides are usually used for “BaseOS” and “AppStream” repositories, whereas composer-cli sources are used for all the other repositories.

Additional resources