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Redis

Redis is the open source, in-memory data store used by millions of developers as a database, cache, streaming engine and message broker.

Introduction

We will be using Redis chart that bootstraps a Redis deployment on a Kubernetes cluster using the Helm package manager.

Prerequisites

  • Kubernetes 1.20+
  • PV provisioner support in the underlying infrastructure
  • Kanister controller version 0.92.0 installed in your cluster, let's assume in Namespace kanister
  • Kanctl CLI installed (https://docs.kanister.io/tooling.html#install-the-tools)
  • Docker CLI installed
  • A docker image containing the required tools to back up Redis. The Dockerfile for the image can be found here. To build and push the docker image to your docker registry, execute these steps.

Build docker image

  • Execute below commands to build and push redis-tools docker image to a registry.
# On your local kanister git repo
$ cd ~/kanister/docker/redis-tools
$ docker build -t <registry>/<account_name>/redis-tools:<tag_name> .
$ docker push <registry>/<account_name>/redis-tools:<tag_name>

Installing the Chart

Execute the below commands to install the Redis database using the bitnami chart with the release name redis:

# Add bitnami in your local chart repository
$ helm repo add bitnami https://charts.bitnami.com/bitnami

# Update your local chart repository
$ helm repo update

# Install the Redis database
$ helm install redis bitnami/redis --namespace redis-test --create-namespace \
    --set auth.password='<redis-password>' --set volumePermissions.enabled=true

The command deploys a Redis instance in the redis-test namespace.

By default a random password will be generated for the user. For setting your own password, use the auth.password param as shown above.

You can retrieve your root password by running the following command. Make sure to replace [YOUR_RELEASE_NAME] and [YOUR_NAMESPACE]:

`kubectl get secret [YOUR_RELEASE_NAME] --namespace [YOUR_NAMESPACE] -o jsonpath="{.data.redis-password}" | base64 -d`

Tip: List all releases using helm list --all-namespaces, using Helm Version 3.

Integrating with Kanister

If you have deployed Redis application with name other than redis and namespace other than redis-test, you need to modify the commands (backup, restore and delete) used below to use the correct release name and namespace.

Create Profile

Create Profile CR if not created already

$ kanctl create profile s3compliant --access-key <aws-access-key-id> \
	--secret-key <aws-secret-key> \
	--bucket <s3-bucket-name> --region <region-name> \
	--namespace redis-test

You can read more about the Profile custom Kanister resource here.

NOTE:

The above command will configure a location where artifacts resulting from Kanister data operations such as backup should go. This is stored as a profiles.cr.kanister.io CustomResource (CR) which is then referenced in Kanister ActionSets. Every ActionSet requires a Profile reference to complete the action. This CR (profiles.cr.kanister.io) can be shared between Kanister-enabled application instances.

Create Blueprint

Create Blueprint in the same namespace as the Kanister controller

NOTE:

Replace <registry>, <account_name> and <tag_name> for the image value in ./redis-blueprint.yaml before running following command.

$ kubectl create -f ./redis-blueprint.yaml -n kanister

Once Redis is running, you can populate it with some data. Let's add a key called "name":

# Connect to Redis by running a shell inside Redis' pod
$ kubectl -n redis-test exec -it redis-master-0 -- bash

# From inside the shell, use the redis-cli to insert some data
# Replace redis-password with the password that you have set while installing Redis
$ redis-cli -a <redis-password>

# Set value for "name" key
127.0.0.1:6379> set name test-redis
OK

# Verify value is properly set
127.0.0.1:6379> get name
"test-redis"

Protect the Application

You can now take a backup of the Redis data using an ActionSet defining backup for this application. Create an ActionSet in the same namespace as the controller.

# Find profile name
$ kubectl get profile -n redis-test
NAME               AGE
s3-profile-75ql6   2m

# Create Actionset
# Make sure the value of profile and blueprint matches the names of profile and blueprint created above
$ kanctl create actionset --action backup --namespace kanister --blueprint redis-blueprint --statefulset redis-test/redis-master --profile redis-test/s3-profile-75ql6 --secrets redis=redis-test/redis
actionset backup-ms8wg created

# View the status of the actionset
$ kubectl --namespace kanister get actionsets.cr.kanister.io backup-ms8wg
NAME           PROGRESS   LAST TRANSITION TIME   STATE
backup-ms8wg   100.00     2022-12-30T08:26:36Z   complete

Disaster strikes!

Let's say someone accidentally deleted the key using the following command:

# Connect to Redis by running a shell inside Redis' pod
$ kubectl -n redis-test exec -it redis-master-0 -- bash

# From inside the shell, use the redis-cli to insert some data
# Replace redis-password with the password that you have set while installing Redis
$ redis-cli -a <redis-password>

# Delete key from Redis
127.0.0.1:6379> get name
"test-redis"

127.0.0.1:6379> del name
(integer) 1

127.0.0.1:6379> get name
(nil)

Restore the Application

To restore the missing data, you should use the backup that you created before. An easy way to do this is to leverage kanctl, a command-line tool that helps create ActionSets that depend on other ActionSets:

# Make sure to use correct backup actionset name here
$ kanctl --namespace kanister create actionset --action restore --from backup-ms8wg
actionset restore-backup-ms8wg-2c4c7 created

# View the status of the ActionSet
$ kubectl --namespace kanister get actionsets.cr.kanister.io restore-backup-ms8wg-2c4c7
NAME                         PROGRESS   LAST TRANSITION TIME   STATE
restore-backup-ms8wg-2c4c7   100.00     2022-12-30T08:42:21Z   complete

Once the ActionSet status is set to "complete", you can verify that the data has been successfully restored to Redis.

# Connect to Redis by running a shell inside Redis' pod
$ kubectl -n redis-test exec -it redis-master-0 -- bash

# From inside the shell, use the redis-cli to insert some data
# Replace redis-password with the password that you have set while installing Redis
$ redis-cli -a <redis-password>

127.0.0.1:6379> get name
"test-redis"

Delete the Artifacts

The artifacts created by the backup action can be cleaned up using the following command:

$ kanctl --namespace kanister create actionset --action delete --from backup-ms8wg --namespacetargets kanister
actionset delete-backup-ms8wg-b6lz4 created

# View the status of the ActionSet
$ kubectl --namespace kanister get actionsets.cr.kanister.io delete-backup-ms8wg-b6lz4
NAME                        PROGRESS   LAST TRANSITION TIME   STATE
delete-backup-ms8wg-b6lz4   100.00     2022-12-30T08:44:40Z   complete

Troubleshooting

If you run into any issues with the above commands, you can check the logs of the controller using:

$ kubectl --namespace kanister logs -l app=kanister-operator

you can also check events of the actionset

$ kubectl describe actionset restore-backup-ms8wg-2c4c7 -n kanister

Cleanup

Uninstalling the Chart

To uninstall/delete the redis deployment:

# Helm Version 3
$ helm delete redis -n redis-test
release "redis" uninstalled

The command removes all the Kubernetes components associated with the chart and deletes the release.

Delete CRs

Remove Blueprint, Profile CR and ActionSets

$ kubectl delete blueprints.cr.kanister.io redis-blueprint -n kanister
blueprint.cr.kanister.io "redis-blueprint" deleted

$ kubectl get profiles.cr.kanister.io -n redis-test
NAME               AGE
s3-profile-75ql6   23m

$ kubectl delete profiles.cr.kanister.io s3-profile-75ql6 -n redis-test
profile.cr.kanister.io "s3-profile-75ql6" deleted

$ kubectl --namespace kanister delete actionsets.cr.kanister.io backup-ms8wg delete-backup-ms8wg-b6lz4 restore-backup-ms8wg-2c4c7
actionset.cr.kanister.io "backup-ms8wg" deleted
actionset.cr.kanister.io "delete-backup-ms8wg-b6lz4" deleted
actionset.cr.kanister.io "restore-backup-ms8wg-2c4c7" deleted