bitnamicharts/redis-cluster

Bitnami Secure Images Helm chart for Redis® Cluster

Redis® is an open source, scalable, distributed in-memory cache for applications. It can be used to store and serve data in the form of strings, hashes, lists, sets and sorted sets.

http://redis.io

Disclaimer: Redis is a registered trademark of Redis Ltd. Any rights therein are reserved to Redis Ltd. Any use by Bitnami is for referential purposes only and does not indicate any ***hip, endorsement, or affiliation between Redis Ltd.

TL;DR

console
helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository.

Introduction

This chart bootstraps a https://github.com/bitnami/containers/tree/main/bitnami/redis deployment on a https://kubernetes.io cluster using the https://helm.sh package manager.

Choose between Redis® Helm Chart and Redis® Cluster Helm Chart

You can choose any of the two Redis® Helm charts for deploying a Redis® cluster. While https://github.com/bitnami/charts/tree/main/bitnami/redis will deploy a master-slave cluster using Redis® Sentinel, the https://github.com/bitnami/charts/tree/main/bitnami/redis-cluster will deploy a Redis® Cluster with sharding. The main features of each chart are the following:

Before you begin

• Kubernetes 1.23+
• Helm 3.8.0+
• PV provisioner support in the underlying infrastructure

Installing the Chart

To install the chart with the release name my-release:

console
helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts.

The command deploys Redis® on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.

NOTE: if you get a timeout error waiting for the hook to complete increase the default timeout (300s) to a higher one, for example:

console
helm install --timeout 600s myrelease oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts. Tip: List all releases using helm list

Configuration and installation details

This section describes credentials, configuration, and other installation options.

Resource requests and limits

Bitnami charts allow setting resource requests and limits for all containers inside the chart deployment. These are inside the resources value (check parameter table). Setting requests is essential for production workloads and these should be adapted to your specific use case.

To make this process easier, the chart contains the resourcesPreset values, which automatically sets the resources section according to different presets. Check these presets in https://github.com/bitnami/charts/blob/main/bitnami/common/templates/_resources.tpl#L15. However, in production workloads using resourcesPreset is discouraged as it may not fully adapt to your specific needs. Find more information on container resource management in the https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/.

Prometheus metrics

This chart can be integrated with Prometheus by setting metrics.enabled to true. This will deploy a sidecar container with https://github.com/oliver006/redis_exporter in all pods and a metrics service, which can be configured under the metrics.service section. This metrics service will have the necessary annotations to be automatically scraped by Prometheus.

Prometheus requirements

It is necessary to have a working installation of Prometheus or Prometheus Operator for the integration to work. Install the https://github.com/bitnami/charts/tree/main/bitnami/prometheus or the https://github.com/bitnami/charts/tree/main/bitnami/kube-prometheus to easily have a working Prometheus in your cluster.

Integration with Prometheus Operator

The chart can deploy ServiceMonitor objects for integration with Prometheus Operator installations. To do so, set the value metrics.serviceMonitor.enabled=true. Ensure that the Prometheus Operator CustomResourceDefinitions are installed in the cluster or it will fail with the following error:

text
no matches for kind "ServiceMonitor" in version "monitoring.coreos.com/v1"

Install the https://github.com/bitnami/charts/tree/main/bitnami/kube-prometheus for having the necessary CRDs and the Prometheus Operator.

https://techdocs.broadcom.com/us/en/vmware-tanzu/bitnami-secure-images/bitnami-secure-images/services/bsi-doc/apps-tutorials-understand-rolling-tags-containers-index.html

It is strongly recommended to use immutable tags in a production environment. This ensures your deployment does not change automatically if the same tag is updated with a different image.

Bitnami will release a new chart updating its containers if a new version of the main container, significant changes, or critical vulnerabilities exist.

Use a different Redis® version

To modify the application version used in this chart, specify a different version of the image using the image.tag parameter and/or a different repository using the image.repository parameter.

Cluster topology

To successfully set the cluster up, it will need to have at least 3 master nodes. The total number of nodes is calculated like- nodes = numOfMasterNodes + numOfMasterNodes * replicas. Hence, the defaults cluster.nodes = 6 and cluster.replicas = 1 means, 3 master and 3 replica nodes will be deployed by the chart.

By default the Redis® Cluster is not accessible from outside the Kubernetes cluster, to access the Redis® Cluster from outside you have to set cluster.externalAccess.enabled=true at deployment time. It will create in the first installation only 6 Load*** services, one for each Redis® node, once you have the external IPs of each service you will need to perform an upgrade passing those IPs to the cluster.externalAccess.service.loadbalancerIP array.

The replicas will be read-only replicas of the masters. By default only one service is exposed (when not using the external access mode). You will connect your client to the exposed service, regardless you need to read or write. When a write operation arrives to a replica it will redirect the client to the proper master node. For example, using redis-cli you will need to provide the -c flag for redis-cli to follow the redirection automatically.

Using the external access mode, you can connect to any of the pods and the slaves will redirect the client in the same way as explained before, but the all the IPs will be public.

In case the master crashes, one of his slaves will be promoted to master. The slots stored by the crashed master will be unavailable until the slave finish the promotion. If a master and all his slaves crash, the cluster will be down until one of them is up again. To avoid downtime, it is possible to configure the number of Redis® nodes with cluster.nodes and the number of replicas that will be assigned to each master with cluster.replicas. For example:

• cluster.nodes=9 ( 3 master plus 2 replicas for each master)
• cluster.replicas=2

Providing the values above, the cluster will have 3 masters and, each master, will have 2 replicas.

NOTE: By default cluster.init will be set to true in order to initialize the Redis® Cluster in the first installation. If for testing purposes you only want to deploy or upgrade the nodes but avoiding the creation of the cluster you can set cluster.init to false.

Adding a new node to the cluster

There is a job that will be executed using a post-upgrade hook that will allow you to add a new node. To use it, you should provide some parameters to the upgrade:

• Pass as password the password used in the installation time. If you did not provide a password follow the instructions from the NOTES.txt to get the generated password.
• Set the desired number of nodes at cluster.nodes.
• Set the number of current nodes at cluster.update.currentNumberOfNodes.
• Set to true cluster.update.addNodes.

The following will be an example to add one more node:

console
helm upgrade --timeout 600s <release> --set "password=${REDIS_PASSWORD},cluster.nodes=7,cluster.update.addNodes=true,cluster.update.currentNumberOfNodes=6" oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts.

Where REDIS_PASSWORD is the password obtained with the command that appears after the first installation of the Helm Chart. The cluster will continue up while restarting pods one by one as the quorum is not lost.

External Access

If you are using external access, to add a new node you will need to perform two upgrades. First upgrade the release to add a new Redis® node and to get a Load***IP service. For example:

console
helm upgrade <release> --set "password=${REDIS_PASSWORD},cluster.externalAccess.enabled=true,cluster.externalAccess.service.type=LoadBalancer,cluster.externalAccess.service.loadBalancerIP[0]=<loadBalancerip-0>,cluster.externalAccess.service.loadBalancerIP[1]=<loadbalanacerip-1>,cluster.externalAccess.service.loadBalancerIP[2]=<loadbalancerip-2>,cluster.externalAccess.service.loadBalancerIP[3]=<loadbalancerip-3>,cluster.externalAccess.service.loadBalancerIP[4]=<loadbalancerip-4>,cluster.externalAccess.service.loadBalancerIP[5]=<loadbalancerip-5>,cluster.externalAccess.service.loadBalancerIP[6]=,cluster.nodes=7,cluster.init=false" oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts. Important here to provide the load***IP parameters for the new nodes empty to not get an index error.

As we want to add a new node, we are setting cluster.nodes=7 and we leave empty the LoadIP for the new node, so the cluster will provide the correct one. REDIS_PASSWORD is the password obtained with the command that appears after the first installation of the Helm Chart. At this point, you will have a new Redis® Pod that will remain in crashLoopBackOff state until we provide the LoadIP for the new service. Now, wait until the cluster provides the new Load***IP for the new service and perform the second upgrade:

console
helm upgrade <release> --set "password=${REDIS_PASSWORD},cluster.externalAccess.enabled=true,cluster.externalAccess.service.type=LoadBalancer,cluster.externalAccess.service.loadBalancerIP[0]=<loadbalancerip-0>,cluster.externalAccess.service.loadBalancerIP[1]=<loadbalancerip-1>,cluster.externalAccess.service.loadBalancerIP[2]=<loadbalancerip-2>,cluster.externalAccess.service.loadBalancerIP[3]=<loadbalancerip-3>,cluster.externalAccess.service.loadBalancerIP[4]=<loadbalancerip-4>,cluster.externalAccess.service.loadBalancerIP[5]=<loadbalancerip-5>,cluster.externalAccess.service.loadBalancerIP[6]=<loadbalancerip-6>,cluster.nodes=7,cluster.init=false,cluster.update.addNodes=true,cluster.update.newExternalIPs[0]=<load-balancerip-6>" oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts.

Note we are providing the new IPs at cluster.update.newExternalIPs, the flag cluster.update.addNodes=true to enable the creation of the Job that adds a new node and now we are setting the Load***IP of the new service instead of leave it empty.

NOTE: To avoid the creation of the Job that initializes the Redis® Cluster again, you will need to provide cluster.init=false.

Scale down the cluster

To scale down the Redis® Cluster, follow these steps:

First perform a normal upgrade setting the cluster.nodes value to the desired number of nodes. It should not be less than 6 and the difference between current number of nodes and the desired should be less or equal to cluster.replicas to avoid removing master node an its slaves at the same time. Also it is needed to provide the password using the password. For example, having more than 6 nodes, to scale down the cluster to 6 nodes:

console
helm upgrade --timeout 600s <release> --set "password=${REDIS_PASSWORD},cluster.nodes=6" .

The cluster will continue working during the update as long as the quorum is not lost.

NOTE: To avoid the creation of the Job that initializes the Redis® Cluster again, you will need to provide cluster.init=false.

Once all the nodes are ready, get the list of nodes in the cluster using the CLUSTER NODES command. You will see references to the ones that were removed. Write down the node IDs of the nodes that show fail. In the following example the cluster scaled down from 7 to 6 nodes.

console
redis-cli -a $REDIS_PASSWORD CLUSTER NODES

...
b23bcffa1fd64368d445c1d9bd9aeb92641105f7 10.0.0.70:6379@16379 slave,fail - 1645633139060 0 0 connected
...

In each cluster node, execute the following command. Replace the NODE_ID placeholder.

console
redis-cli -a $REDIS_PASSWORD CLUSTER FORGET NODE_ID

In the previous example the commands would look like this in each cluster node:

console
redis-cli -a $REDIS_PASSWORD CLUSTER FORGET b23bcffa1fd64368d445c1d9bd9aeb92641105f7

Using password file

To use a password file for Redis® you need to create a secret containing the password.

NOTE: It is important that the file with the password must be called redis-password

And then deploy the Helm Chart using the secret name as parameter:

text
usePassword=true
usePasswordFile=true
existingSecret=redis-password-secret
metrics.enabled=true

Securing traffic using TLS

TLS support can be enabled in the chart by specifying the tls. parameters while creating a release. The following parameters should be configured to properly enable the TLS support in the cluster:

• tls.enabled: Enable TLS support. Defaults to false
• tls.existingSecret: Name of the secret that contains the certificates. No defaults.
• tls.certFilename: Certificate filename. No defaults.
• tls.certKeyFilename: Certificate key filename. No defaults.
• tls.certCAFilename: CA Certificate filename. No defaults.

For example:

First, create the secret with the certificates files:

console
kubectl create secret generic certificates-tls-secret --from-file=./cert.pem --from-file=./cert.key --from-file=./ca.pem

Then, use the following parameters:

console
tls.enabled="true"
tls.existingSecret="certificates-tls-secret"
tls.certFilename="cert.pem"
tls.certKeyFilename="cert.key"
tls.certCAFilename="ca.pem"

Sidecars and Init Containers

If you have a need for additional containers to run within the same pod as Redis® (e.g. an additional metrics or logging exporter), you can do so via the sidecars config parameter. Simply define your container according to the Kubernetes container spec.

yaml
sidecars:
  - name: your-image-name
    image: your-image
    imagePullPolicy: Always
    ports:
      - name: portname
       containerPort: 1234

Similarly, you can add extra init containers using the initContainers parameter.

yaml
initContainers:
  - name: your-image-name
    image: your-image
    imagePullPolicy: Always
    ports:
      - name: portname
        containerPort: 1234

Adding extra environment variables

In case you want to add extra environment variables (useful for advanced operations like custom init scripts), you can use the extraEnvVars property.

yaml
extraEnvVars:
  - name: REDIS_WHATEVER
    value: value

Alternatively, you can use a ConfigMap or a Secret with the environment variables. To do so, use the extraEnvVarsCM or the extraEnvVarsSecret values.

Metrics

The chart optionally can start a metrics exporter for [***] The metrics endpoint (port 9121) is exposed in the service. Metrics can be scraped from within the cluster using something similar as the described in the https://github.com/prometheus/prometheus/blob/master/documentation/examples/prometheus-kubernetes.yml. If metrics are to be scraped from outside the cluster, the Kubernetes API proxy can be utilized to access the endpoint.

Host Kernel Settings

Redis® may require some changes in the kernel of the host machine to work as expected, in particular increasing the somaxconn value and disabling transparent huge pages. To do so, you can set up a privileged initContainer with the sysctlImage config values, for example:

yaml
sysctlImage:
  enabled: true
  mountHostSys: true
  command:
    - /bin/sh
    - -c
    - |-
      sysctl -w net.core.somaxconn=10000
      echo never > /host-sys/kernel/mm/transparent_hugepage/enabled

Alternatively, for Kubernetes 1.12+ you can set podSecurityContext.sysctls which will configure sysctls for master and slave pods. Example:

yaml
podSecurityContext:
  sysctls:
  - name: net.core.somaxconn
    value: "10000"

Note that this will not disable transparent huge tables.

Helm Upgrade

By default cluster.init will be set to true in order to initialize the Redis® Cluster in the first installation. If for testing purposes you only want to deploy or upgrade the nodes but avoiding the creation of the cluster you can set cluster.init to false.

FIPS parameters

The FIPS parameters only have effect if you are using images from the https://go-vmware.broadcom.com/contact-us.

For more information on this new support, please refer to the https://techdocs.broadcom.com/us/en/vmware-tanzu/bitnami-secure-images/bitnami-secure-images/services/bsi-doc/security-frameworks-FIPS-compliance.html.

Backup and restore

To back up and restore Redis Cluster Helm chart deployments on Kubernetes, you need to back up the persistent volumes from the source deployment and attach them to a new deployment using https://velero.io/, a Kubernetes backup/restore tool.

These are the steps you will usually follow to back up and restore your Redis Cluster database cluster data:

• Install Velero on the source and destination clusters.
• Use Velero to back up the PersistentVolumes (PVs) used by the deployment on the source cluster.
• Use Velero to restore the backed-up PVs on the destination cluster.
• Create a new deployment on the destination cluster with the same chart, deployment name, credentials and other parameters as the original. This new deployment will use the restored PVs and hence the original data.

Refer to our detailed https://techdocs.broadcom.com/us/en/vmware-tanzu/bitnami-secure-images/bitnami-secure-images/services/bsi-doc/apps-tutorials-backup-restore-data-redis-cluster-kubernetes-index.html for more information.

NetworkPolicy

To enable network policy for Redis®, install https://kubernetes.io/docs/tasks/administer-cluster/declare-network-policy#before-you-begin, and set networkPolicy.enabled to true.

For Kubernetes v1.5 & v1.6, you must also turn on NetworkPolicy by setting the DefaultDeny namespace annotation. Note: this will enforce policy for all pods in the namespace:

console
kubectl annotate namespace default "net.beta.kubernetes.io/network-policy={\"ingress\":{\"isolation\":\"DefaultDeny\"}}"

With NetworkPolicy enabled, only pods with the generated client label will be able to connect to Redis®. This label will be displayed in the output after a successful install.

With networkPolicy.ingressNSMatchLabels pods from other namespaces can connect to redis. Set networkPolicy.ingressNSPodMatchLabels to match pod labels in matched namespace. For example, for a namespace labeled redis=external and pods in that namespace labeled redis-client=true the fields should be set:

yaml
networkPolicy:
  enabled: true
  ingressNSMatchLabels:
    redis: external
  ingressNSPodMatchLabels:
    redis-client: true

Setting Pod's affinity

This chart allows you to set your custom affinity using the XXX.affinity paremeter(s). Find more information about Pod's affinity in the https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity.

As an alternative, you can use of the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the https://github.com/bitnami/charts/tree/main/bitnami/common#affinities chart. To do so, set the XXX.podAffinityPreset, XXX.podAntiAffinityPreset, or XXX.nodeAffinityPreset parameters.

Persistence

By default, the chart mounts a https://kubernetes.io/docs/concepts/storage/persistent-volumes/ at the /bitnami path. The volume is created using dynamic volume provisioning.

If persistence is disabled, an emptyDir volume is used. This is only recommended for testing environments because the required information included in the nodes.conf file is missing. This file contains the relationship between the nodes and the cluster. For example, if any node is down or faulty, when it starts again, it is a self-proclaimed master and also acts as an independent node outside the main cluster as it doesn't have the necessary information to connect to it.

To reconnect the failed node, run the following:

See nodes.sh

console
$ cat /bitnami/redis/data/nodes.sh
declare -A host_2_ip_array=([redis-node-0]="192.168.192.6" [redis-node-1]="192.168.192.2" [redis-node-2]="192.168.192.4" [redis-node-3]="192.168.192.5" [redis-node-4]="1

_Note: the README for this chart is longer than the DockerHub length limit of 25000, so it has been trimmed. The full README can be found at https://techdocs.broadcom.com/us/en/vmware-tanzu/bitnami-secure-images/bitnami-secure-images/services/bsi-app-doc/apps-charts-redis-cluster-index.html_