Upgrade a Redis Enterprise cluster (REC) on Kubernetes

Redis implements rolling updates for software upgrades in Kubernetes deployments. The upgrade process consists of two steps:

1. Upgrade the Redis Enterprise operator
2. Upgrade the Redis Enterprise cluster (REC)

Upgrade the operator

Download the bundle

Make sure you pull the correct version of the bundle. You can find the version tags by checking the operator releases on GitHub or by using the GitHub API.

You can download the bundle for the latest release with the following curl command:

VERSION=`curl --silent https://api.github.com/repos/RedisLabs/redis-enterprise-k8s-docs/releases/latest | grep tag_name | awk -F'"' '{print $4}'`
curl --silent -O https://raw.githubusercontent.com/RedisLabs/redis-enterprise-k8s-docs/$VERSION/bundle.yaml

For OpenShift environments, the name of the bundle is openshift.bundle.yaml, and so the curl command to run is:

curl --silent -O https://raw.githubusercontent.com/RedisLabs/redis-enterprise-k8s-docs/$VERSION/openshift.bundle.yaml

If you need a different release, replace VERSION in the above with a specific release tag.

Apply the bundle

Apply the bundle to deploy the new operator binary. This will also apply any changes in the new release to custom resource definitions, roles, role binding, or operator service accounts.

Upgrade the bundle and operator with a single command, passing in the bundle YAML file:

kubectl apply -f bundle.yaml

If you are using OpenShift, run this instead:

kubectl apply -f openshift.bundle.yaml

After running this command, you should see a result similar to this:

role.rbac.authorization.k8s.io/redis-enterprise-operator configured
serviceaccount/redis-enterprise-operator configured
rolebinding.rbac.authorization.k8s.io/redis-enterprise-operator configured
customresourcedefinition.apiextensions.k8s.io/redisenterpriseclusters.app.redislabs.com configured
customresourcedefinition.apiextensions.k8s.io/redisenterprisedatabases.app.redislabs.com configured
deployment.apps/redis-enterprise-operator configured

Reapply other manual configurations

When upgrading the operator, there are few configurations you’ll need to reapply.

If you have the admission controller enabled, you need to manually reapply the ValidatingWebhookConfiguration. See the Enable the admission controller step during deployment for more details.

If you are using OpenShift, you will also need to manually reapply the Security context constraints file (scc.yaml).

oc apply -f openshift/scc.yaml

Verify the operator is running

You can check your deployment to verify the operator is running in your namespace.

kubectl get deployment/redis-enterprise-operator

You should see a result similar to this:

NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
redis-enterprise-operator   1/1     1            1           0m36s

Upgrade the Redis Enterprise cluster (REC)

The Redis Enterprise cluster (REC) can be updated automatically or manually. To trigger automatic upgrade of the REC after the operator upgrade completes, specify autoUpgradeRedisEnterprise: true in your REC spec. If you don’t have automatic upgrade enabled, follow the below steps for the manual upgrade.

Before beginning the upgrade of the Redis Enterprise cluster, check the K8s operator release notes to find the Redis Enterprise image tag. For example, in Redis Enterprise K8s operator release 6.0.12-5, the Images section shows the Redis Enterprise tag is 6.0.12-57.

After the operator upgrade is complete, you can upgrade Redis Enterprise cluster (REC).

Edit redisEnterpriseImageSpec in the REC spec

1. Edit the REC custom resource YAML file.

   kubectl edit rec <your-rec.yaml>
   

2. Replace the versionTag: declaration under redisEnterpriseImageSpec with the new version tag.

   spec:
     redisEnterpriseImageSpec:
       imagePullPolicy:  IfNotPresent
       repository:       redislabs/redis
       versionTag:       <new-version-tag>
   

3. Save the changes to apply.

Monitor the upgrade

You can view the state of the REC with kubectl get rec.

During the upgrade, the state should be Upgrade. When the upgrade is complete and the cluster is ready to use, the state will change to Running. If the state is InvalidUpgrade, there is an error (usually relating to configuration) in the upgrade.

$ kubectl get rec
NAME   NODES   VERSION      STATE     SPEC STATUS   LICENSE STATE   SHARDS LIMIT   LICENSE EXPIRATION DATE   AGE
rec    3       6.2.10-107   Upgrade   Valid         Valid           4              2022-07-16T13:59:00Z      92m

To see the status of the current rolling upgrade, run:

kubectl rollout status sts <REC_name>

Upgrade databases

After the cluster is upgraded, you can upgrade your databases. The process for upgrading databases is the same for both Kubernetes and non-Kubernetes deployments. For more details on how to upgrade a database, see the Upgrade an existing Redis Enterprise Software deployment documentation.

Note that if your cluster redisUpgradePolicy or your database redisVersion are set to major, you won’t be able to upgrade those databases to minor versions. See Redis upgrade policy for more details.

How does the REC upgrade work?

The Redis Enterprise cluster (REC) uses a rolling upgrade, meaning it upgrades pods one by one. Each pod is updated after the last one completes successfully. This helps keep your cluster available for use.

To upgrade, the cluster terminates each pod and deploys a new pod based on the new image. Before each pod goes down, the operator checks if the pod is a primary (master) for the cluster, and if it hosts any primary (master) shards. If so, a replica on a different pod is promoted to primary. Then when the pod is terminated, the API remains available through the newly promoted primary pod.

After a pod is updated, the next pod is terminated and updated. After all of the pods are updated, the upgrade process is complete.