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

Chapter 8 ■ Using Rolling Updates
Figure 8-4. Listing the nodes
The kubectl rolling-update command is used to perform a rolling update. The syntax for the
rolling-update command is as follows.
kubectl rolling-update OLD_CONTROLLER_NAME ([NEW_CONTROLLER_NAME] --image=NEW_CONTAINER_
IMAGE | -f NEW_CONTROLLER_SPEC)
The old container name is required to be specified, and if a new controller name is to be assigned to
the updated RC, a new controller name may be specified. Either a new container image or a new container
specification must be specified as a command parameter. Next, we shall discuss performing a rolling update
using each of the methods; a new container image and a new controller specification.
Rolling Update with an RC Definition File
In this section we’ll discuss the rolling update of an existing replication controller by providing an RC
definition file to the kubectl rolling-update command. The following requirements apply for rollingupdating
an RC.
1. The new replication controller must be in the same namespace.
2. The new replication controller name in the definition file must not be the same
as the existing replication controller being updated.
3. The new replication controller must specify at least one matching key with a
nonequal value in the selector field.
First, create a replication controller to be updated. The following RC definition file mysql.yaml creates
an RC called mysql and specifies three replicas. Create a definition file mysql.yaml in a vi editor:
sudo vi mysql.yaml
Copy the following source code to the definition file:
---
apiVersion: v1
kind: ReplicationController
metadata:
name: mysql
labels:
app: mysql-app
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