148422597X Kubernetes Management Design Patterns [Vohra 2017-01-29] {E559F6BB}

Chapter 8 ■ Using Rolling Updates
The rolling update is completed using an existing update as shown in Figure 8-19. Next, list the new RC
and pods.
Figure 8-19. Rolling update using existing update
Rolling Back an Update
A rollback of a rolling update can be performed if required. As an example, a rolling update to an RC called
postgresql is started using a new container image mysql:
kubectl rolling-update postgresql mysql --image=mysql
Now suppose that while the rolling update is still in progress, we realize the update should not have
been started, or was started in error, or needs to be started with different parameters. Using ^C, terminate
the update. Then run the following command to roll back the update:
kubectl rolling-update postgresql mysql –rollback
When the rolling update was terminated, the postgresql RC had already scaled down to one pod and
the mysql RC had already scaled up to two pods. When the rollback is performed, the existing controller
postgresql is scaled back up from one to three pods and the mysql RC is scaled down from two to zero pods,
as shown in Figure 8-20.
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