bitnamicharts/redis-cluster
Bitnami Helm chart for Redis(R) Cluster
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Redis(R) 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.
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 sponsorship, endorsement, or affiliation between Redis Ltd.
helm install my-release oci://registry-1.docker.io/bitnamicharts/redis-cluster
Looking to use Redisreg; Cluster in production? Try VMware Tanzu Application Catalog, the commercial edition of the Bitnami catalog.
This chart bootstraps a Redis® deployment on a Kubernetes cluster using the Helm package manager.
Bitnami charts can be used with Kubeapps for deployment and management of Helm Charts in clusters.
You can choose any of the two Redis® Helm charts for deploying a Redis® cluster. While Redis® Helm Chart will deploy a master-slave cluster using Redis® Sentinel, the Redis® Cluster Helm Chart will deploy a Redis® Cluster with sharding. The main features of each chart are the following:
Redis® | Redis® Cluster |
---|---|
Supports multiple databases | Supports only one database. Better if you have a big dataset |
Single write point (single master) | Multiple write points (multiple masters) |
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To install the chart with the release name my-release
:
helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster
Note: You need to substitute the placeholders
REGISTRY_NAME
andREPOSITORY_NAME
with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to useREGISTRY_NAME=registry-1.docker.io
andREPOSITORY_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:
helm install --timeout 600s myrelease oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster
Note: You need to substitute the placeholders
REGISTRY_NAME
andREPOSITORY_NAME
with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to useREGISTRY_NAME=registry-1.docker.io
andREPOSITORY_NAME=bitnamicharts
. Tip: List all releases usinghelm list
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 the bitnami/common chart. 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 official Kubernetes documentation.
This chart can be integrated with Prometheus by setting metrics.enabled
to true
. This will deploy a sidecar container with 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 Bitnami Prometheus helm chart or the Bitnami Kube Prometheus helm chart 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:
no matches for kind "ServiceMonitor" in version "monitoring.coreos.com/v1"
Install the Bitnami Kube Prometheus helm chart for having the necessary CRDs and the Prometheus Operator.
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.
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.
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 LoadBalancer 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 totrue
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 setcluster.init
tofalse
.
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:
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.cluster.nodes
.cluster.update.currentNumberOfNodes
.cluster.update.addNodes
.The following will be an example to add one more node:
helm upgrade --timeout 600s <release> --set "password=${REDIS_PASSWORD},cluster.nodes=7,cluster.update.addNodes=true,cluster.update.currentNumberOfNodes=6" oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster
Note: You need to substitute the placeholders
REGISTRY_NAME
andREPOSITORY_NAME
with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to useREGISTRY_NAME=registry-1.docker.io
andREPOSITORY_NAME=bitnamicharts
.
Where REDIS_PASSWORD
is the password obtained with the command that appears after the first installation of the Helm Chart.
The cluster will continue up while restarting pods one by one as the quorum is not lost.
If you are using external access, to add a new node you will need to perform two upgrades. First upgrade the release to add a new Redis® node and to get a LoadBalancerIP service. For example:
helm upgrade <release> --set "password=${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
andREPOSITORY_NAME
with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to useREGISTRY_NAME=registry-1.docker.io
andREPOSITORY_NAME=bitnamicharts
. Important here to provide the loadBalancerIP 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 LoadBalancerIP 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 LoadBalancerIP for the new service.
Now, wait until the cluster provides the new LoadBalancerIP for the new service and perform the second upgrade:
helm upgrade <release> --set "password=${REDIS_PASSWORD},cluster.externalAccess.enabled=true,cluster.externalAccess.service.type=LoadBalancer,cluster.externalAccess.service.loadBalancerIP[0]=<loadbalancerip-0>,cluster.externalAccess.service.loadBalancerIP[1]=<loadbalancerip-1>,cluster.externalAccess.service.loadBalancerIP[2]=<loadbalancerip-2>,cluster.externalAccess.service.loadBalancerIP[3]=<loadbalancerip-3>,cluster.externalAccess.service.loadBalancerIP[4]=<loadbalancerip-4>,cluster.externalAccess.service.loadBalancerIP[5]=<loadbalancerip-5>,cluster.externalAccess.service.loadBalancerIP[6]=<loadbalancerip-6>,cluster.nodes=7,cluster.init=false,cluster.update.addNodes=true,cluster.update.newExternalIPs[0]=<load-balancerip-6>" oci://REGISTRY_NAME/REPOSITORY_NAME/redis-cluster
Note: You need to substitute the placeholders
REGISTRY_NAME
andREPOSITORY_NAME
with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to useREGISTRY_NAME=registry-1.docker.io
andREPOSITORY_NAME=bitnamicharts
.
Note we are providing the new IPs at cluster.update.newExternalIPs
, the flag cluster.update.addNodes=true
to enable the creation of the Job that adds a new node and now we are setting the LoadBalancerIP of the new service instead of leave it empty.
NOTE: To avoid the creation of the Job that initializes the Redis® Cluster again, you will need to provide
cluster.init=false
.
Scale down the cluster
To scale down the Redis® Cluster, follow these steps:
First perform a normal upgrade setting the cluster.nodes
value to the desired number of nodes. It should not be less than 6
and the difference between current number of nodes and the desired should be less or equal to cluster.replicas
to avoid removing master node an its slaves at the same time. Also it is needed to provide the password using the password
. For example, having more than 6 nodes, to scale down the cluster to 6 nodes:
helm upgrade --timeout 600s <release> --set "password=${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.
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.
redis-cli -a $REDIS_PASSWORD CLUSTER FORGET NODE_ID
In the previous example the commands would look like this in each cluster node:
redis-cli -a $REDIS_PASSWORD CLUSTER FORGET b23bcffa1fd64368d445c1d9bd9aeb92641105f7
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:
usePassword=true
usePasswordFile=true
existingSecret=redis-password-secret
metrics.enabled=true
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:
kubectl create secret generic certificates-tls-secret --from-file=./cert.pem --from-file=./cert.key --from-file=./ca.pem
Then, use the following parameters:
tls.enabled="true"
tls.existingSecret="certificates-tls-secret"
tls.certFilename="cert.pem"
tls.certKeyFilename="cert.key"
tls.certCAFilename="ca.pem"
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.
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.
initContainers:
- name: your-image-name
image: your-image
imagePullPolicy: Always
ports:
- name: portname
containerPort: 1234
In case you want to add extra environment variables (useful for advanced operations like custom init scripts), you can use the extraEnvVars
property.
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.
The chart optionally can start a metrics exporter for prometheus. 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 example Prometheus scrape configuration. If metrics are to be scraped from outside the cluster, the Kubernetes API proxy can be utilized to access the endpoint.
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:
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:
podSecurityContext:
sysctls:
- name: net.core.somaxconn
value: "10000"
Note that this will not disable transparent huge tables.
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
.
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 Velero, a Kubernetes backup/restore tool.
These are the steps you will usually follow to back up and restore your Redis Cluster database cluster data:
Refer to our detailed tutorial on backing up and restoring Redis Cluster deployments on Kubernetes for more information.
To enable network policy for Redis®, install
a networking plugin that implements the Kubernetes NetworkPolicy spec,
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:
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:
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 kubernetes documentation.
As an alternative, you can use of the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the bitnami/common chart. To do so, set the XXX.podAffinityPreset
, XXX.podAntiAffinityPreset
, or XXX.nodeAffinityPreset
parameters.
By default, the chart mounts a Persistent Volume 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
$ 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]="192.168.192.3" [redis-node-5]="192.168.192.7" )
Run redis-cli and run CLUSTER MEET to any other node in the cluster. Now the node has connected to the main cluster.
$ REDISCLI_AUTH=bitnami redis-cli
127.0.0.1:6379> cluster meet 192.168.192.7 6379
OK
See #15075
| Name | Description | Value | | ----------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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://github.com/bitnami/charts/blob/main/bitnami/redis-cluster/README.md