{
  "id": "replica-redb",
  "title": "Create replica databases on Kubernetes",
  "url": "https://redis.io/docs/latest/operate/kubernetes/7.8.4/re-databases/replica-redb/",
  "summary": "How to create and automate database replicas using the database controller",
  "content": "\nYou can configure a replica of a database by creating an item in\nthe [`replicaSources`]() section of the RedisEnterpriseDatabase (REDB) custom resource.\n\nA secret must be created with the `stringData` section containing the replica source URI as follows:\n\nCreate a secret with the replica source URI listed in the `stringData` field as follows:\n\n```yaml\napiVersion: v1\nkind: Secret\nmetadata:\n   name: my-replica-source\nstringData:\n   uri: \u003creplica-source-uri-goes-here\u003e\n```\n\nThe replica source URL can be retrieved by going to \"UI \u003e database \u003e configuration \u003e Press the button Get Replica of source URL\"\nin the administrative UI. But, this information can also be retrieved directly from\nthe REST API as well.\n\nA replica of database CR simply uses the secret in the `replicaSources` section:\n\n```yaml\napiVersion: app.redislabs.com/v1alpha1\nkind: RedisEnterpriseDatabase\nmetadata:\n   name: name-of-replica\nspec:\n   redisEnterpriseCluster:\n      name: name-of-cluster\n   replicaSources:\n   - replicaSourceType: SECRET\n     replicaSourceName: my-replica-source\n```\n\nIn the above, `name-of-replica` database will be created as a replica of the\nsource database as long as the source database exists on the source cluster\nand the secret contains the correct replica source URL for that database.\n\n## Retrieving the replica source URL via kubectl\n\nYou will need `kubectl`, `curl`, and `jq` installed for this procedure.\n\n1. Set your metadata:\n\n   ```js\n   CLUSTER_NAME=test\n   SOURCE_DB=db1\n   TARGET_DB=db2\n   TARGET_CLUSTER_NAME=test\n   ```\n\n1. Retrieve the cluster authentication:\n\n   ```js\n   CLUSTER_USER=`kubectl get secret/${CLUSTER_NAME} -o json | jq -r .data.username | base64 -d`\n   CLUSTER_PASSWORD=`kubectl get secret/${CLUSTER_NAME} -o json | jq -r .data.password | base64 -d`\n   ```\n\n1. Forward the port of the REST API service for your source cluster:\n\n   ```sh\n   kubectl port-forward pod/${CLUSTER_NAME}-0 9443\n   ```\n\n1. Request the information from the REST API:\n\n   ```js\n   JQ='.[] | select(.name==\"'\n   JQ+=\"${SOURCE_DB}\"\n   JQ+='\") | (\"redis://admin:\" + .authentication_admin_pass + \"@\"+.name+\":\"+(.endpoints[0].port|tostring))'\n   URI=`curl -sf -k -u \"$CLUSTER_USER:$CLUSTER_PASSWORD\" \"https://localhost:9443/v1/bdbs?fields=uid,name,endpoints,authentication_admin_pass\" | jq \"$JQ\" | sed 's/\"//g'`\n   ```\n\n   Note: URI now contains the replica source URI.\n\n1. Construct the secret for the replica:\n\n   ```yaml\n   cat \u003c\u003c EOF \u003e secret.yaml\n   apiVersion: v1\n   kind: Secret\n   metadata:\n     name: ${SOURCE_DB}-url\n   stringData:\n     uri: ${URI}\n   EOF\n   kubectl apply -f secret.yaml\n   ```\n\n1. Create the replica database:\n\n   ```yaml\n   cat \u003c\u003c EOF \u003e target.yaml\n   apiVersion: app.redislabs.com/v1alpha1\n   kind: RedisEnterpriseDatabase\n   metadata:\n     name: ${TARGET_DB}\n   spec:\n     redisEnterpriseCluster:\n       name: ${TARGET_CLUSTER_NAME}\n     replicaSources:\n     - replicaSourceType: SECRET\n       replicaSourceName: ${SOURCE_DB}-url\n   EOF\n   kubectl apply -f target.yaml\n   ```\n\n## Automating the creation via a job\n\nThe following procedure uses a ConfigMap and a Job to construct the replica\nsource URL secret from the source database and configure the target database.\n\nThere are four parameters:\n\n- `source` - the name of the source database\n- `cluster` - the name of the cluster for the source database\n- `target` - the name of the target database\n- `targetCluster` - the name of the cluster for the target database\n\nThese parameters can be set by:\n\n```sh\nkubectl create configmap replica-of-database-parameters \\\n--from-literal=source=name-of-source \\\n--from-literal=cluster=name-of-cluster \\\n--from-literal=target=name-of-target \\\n--from-literal=targetCluster=name-of-cluster\n```\n\nwhere \"name-of-...\" is replaced with the database source, source cluster,\ndatabase target, and target cluster names.\n\nThe Job and ConfigMap below, when submitted, will create the secret and\nreplica database:\n\n```yaml\napiVersion: batch/v1\nkind: Job\nmetadata:\n  name: replica-of-database\nspec:\n  backoffLimit: 4\n  template:\n    spec:\n      serviceAccountName: redis-enterprise-operator\n      restartPolicy: Never\n      volumes:\n        - name: scripts\n          configMap:\n            name: replica-of-database\n      containers:\n        - name: createdb\n          image: debian:stable-slim\n          env:\n            - name: MY_NAMESPACE\n              valueFrom:\n                fieldRef:\n                  fieldPath: metadata.namespace\n            - name: SCRIPT\n              value: create.sh\n            - name: SOURCE_DB\n              valueFrom:\n                configMapKeyRef:\n                  name: replica-of-database-parameters\n                  key: source\n            - name: TARGET_DB\n              valueFrom:\n                configMapKeyRef:\n                  name: replica-of-database-parameters\n                  key: target\n            - name: CLUSTER_SERVICE\n              value: .svc.cluster.local\n            - name: CLUSTER_NAME\n              valueFrom:\n                configMapKeyRef:\n                  name: replica-of-database-parameters\n                  key: cluster\n            - name: CLUSTER_PORT\n              value: \"9443\"\n            - name: TARGET_CLUSTER_NAME\n              valueFrom:\n                configMapKeyRef:\n                  name: replica-of-database-parameters\n                  key: targetCluster\n          volumeMounts:\n            - mountPath: /opt/scripts/\n              name: scripts\n          command:\n            - /bin/bash\n            - -c\n            - |\n              apt-get update; apt-get install -y curl jq apt-transport-https gnupg2\n              apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6A030B21BA07F4FB\n              curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -\n              echo \"deb https://apt.kubernetes.io/ kubernetes-xenial main\" | tee -a /etc/apt/sources.list.d/kubernetes.list\n              apt-get update\n              apt-get install -y kubectl\n              bash /opt/scripts/$SCRIPT\n---\napiVersion: v1\nkind: ConfigMap\nmetadata:\n  name: replica-of-database\ndata:\n  create.sh: |\n    CLUSTER_USER=`kubectl get secret/${CLUSTER_NAME} -o json | jq -r .data.username | base64 -d`\n    CLUSTER_PASSWORD=`kubectl get secret/${CLUSTER_NAME} -o json | jq -r .data.password | base64 -d`\n    CLUSTER_HOST=${CLUSTER_NAME}.${MY_NAMESPACE}${CLUSTER_SERVICE}\n    JQ='.[] | select(.name==\"'\n    JQ+=\"${SOURCE_DB}\"\n    JQ+='\") | (\"redis://admin:\" +  .authentication_admin_pass + \"@\"+.endpoints[0].dns_name+\":\"+(.endpoints[0].port|tostring))'\n    URI=`curl -sf -k -u \"$CLUSTER_USER:$CLUSTER_PASSWORD\" \"https://${CLUSTER_HOST}:${CLUSTER_PORT}/v1/bdbs?fields=uid,name,endpoints,authentication_admin_pass\" | jq \"$JQ\" | sed 's/\"//g'`\n    echo \"URL: ${URL}\"\n    echo \"\"\n    cat \u003c\u003c EOF \u003e /tmp/secret.yaml\n    apiVersion: v1\n    kind: Secret\n    metadata:\n      name: ${SOURCE_DB}-url\n    stringData:\n      uri: ${URI}\n    EOF\n    cat /tmp/secret.yaml\n    cat \u003c\u003c EOF \u003e /tmp/target.yaml\n    apiVersion: app.redislabs.com/v1alpha1\n    kind: RedisEnterpriseDatabase\n    metadata:\n      name: ${TARGET_DB}\n    spec:\n      redisEnterpriseCluster:\n        name: ${TARGET_CLUSTER_NAME}\n      replicaSources:\n      - replicaSourceType: SECRET\n        replicaSourceName: ${SOURCE_DB}-url\n    EOF\n    echo \"---\"\n    cat /tmp/target.yaml\n    echo \"\"\n    kubectl -n ${MY_NAMESPACE} apply -f /tmp/secret.yaml\n    kubectl -n ${MY_NAMESPACE} apply -f /tmp/target.yaml\n```\n",
  "tags": ["docs","operate","kubernetes"],
  "last_updated": "2026-04-08T12:21:52-07:00"
}