Deploying a specific version of Red Hat Enterprise Linux Atomic Host

Environment

• Red Hat Enterprise Linux Atomic Host 7.x

Issue

As a customer, I would like the ability to move to any released version of Red Hat Enterprise Linux Atomic Host.

Resolution

Red Hat Enterprise Linux Atomic Host release version commit IDs

In order to move to arbitrary releases of Red Hat Enterprise Linux Atomic Host, you must provide the full release commit ID. The table below lists the commit IDs for all Red Hat Enterprise Linux Atomic Host releases:

Determining the Version Commit ID from the command line.

In addition to the table above, the version commit ID for all releases versions of RHEL Atomic Host can be found with the following commands:

# ostree pull --depth=-1 --commit-metadata-only rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard
# ostree log rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard
commit 9bfe1fb65094d43e420490196de0e9aea26b3923f1c18ead557460b83356f058    <=== Version ID
Date:  2016-06-18 15:21:12 +0000
Version: 7.2.5
[...]

Moving to arbitrary versions of Red Hat Enterprise Linux Atomic Host

There are two methods for switching to an arbitrary version of Red Hat Enterprise Linux Atomic Host. Both are described below.

NOTE: - Modified configuration files will not be modified when switching to an arbitrary release. If the configuration format or arguments have changed, config files will need to be adjusted to match.

Method 1a: Using the atomic command to move to a specific version (supported in RHEL AH versions 7.2.4 and newer)

This method uses the built-in atomic commands to simplify moving to a specific version.

-bash-4.2# atomic host status
  TIMESTAMP (UTC)         VERSION     ID             OSNAME               REFSPEC                                                        
* 2016-05-06 05:57:30     7.2.4       b060975ce3     rhel-atomic-host     rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard     
  2016-04-12 14:20:45     7.2.3-1     644fcc6035     rhel-atomic-host     rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard     

Then, use atomic host deploy to move to the desired version:

# atomic host deploy <version commit ID>
# systemctl reboot

Method 1b: Moving to an specific version manually without locking it down (supported in all RHEL AH versions)

This method is the manual version of the atomic host deploy command above. It allows you to move to a particular version of Atomic Host, but atomic host upgrade will still move to the latest version. To do it, you will need to use a release refspec. The refspec can be seen when the atomic host status command is run.

# atomic host status
  TIMESTAMP (UTC)         VERSION   ID             OSNAME               REFSPEC                                                        
* 2015-12-03 19:40:36     7.2.1     aaf67b91fa     rhel-atomic-host     rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard  

# ostree pull rhel-atomic-host-ostree <version commit ID>
# ostree reset rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard  <version commit ID>
# ostree admin deploy rhel-atomic-host-ostree:rhel-atomic-host/7/x86_64/standard
# systemctl reboot

Method 2: Manually moving to a specific version and locking a system to an specific version (supported in all versions of RHEL AH)

This method "locks you in" to a particular release, requiring an atomic host rollback before being able to upgrade again. This method is ideal if you do not want the Atomic Host to be upgraded inadvertently.

# ostree pull rhel-atomic-host-ostree <version commit ID>
# ostree admin deploy <version commit ID>
# systemctl reboot

Any attempt to upgrade will show that the Atomic Host has no upgrade available:

# atomic host upgrade
Updating from: <version commit ID>


No upgrade available.

To "unlock" the Atomic Host, rollback and reboot. Once rebooted, the system will upgrade normally.

# atomic host rollback
# systemctl reboot

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