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Configuring Splunk Enterprise Multisite Deployments

This document provides examples to configure a multisite cluster using the splunk-operator.

Please refer to the Configuring Splunk Enterprise Deployments Guide for more information and examples about deploying the different Splunk resources in single site mode.

Multisite Indexer Clusters in Kubernetes

Multisite indexer cluster architecture can be used for various purposes. However, Kubernetes clusters are generally deployed at the scale of a region, and the main purpose of this documentation is to cover the topic of building high-available indexer clusters allowing to control the placement of bucket replicas across multiple availability zones, to prevent the failure of a single zone from causing events to be unavailable for search or permanently lost.

Designing applications requiring high-availability to support the loss of a zone is a recommendation from all cloud providers (e.g. GCP, AWS, Azure). In a private datacenter, multisite indexer clusters can be used to support the loss of a room or rack. In the case of dedicated hardware with local storage used for Splunk (or various datastores), a multisite indexer cluster allows to support regular maintenance (e.g. OS upgrades) in the case of multiple indexer pods scheduled on the same host.

Multipart IndexerCluster

Description: connect multiple IndexerCluster resources to ClusterManager resource, each constrained to run within a dedicated zone and configured with a hardcoded site.

Advantages:

  • some operations are performed per site which mitigates the risk of impact on the whole cluster (e.g. Splunk upgrades, scaling up resources)
  • specific indexer services are created per site allowing to send events to the indexers located in the same zone, avoiding possible cost of cross-zone traffic. Indexer discovery from cluster-manager can do this for forwarders, but this solution also covers http/HEC traffic

Limitation: all the IndexerCluster resources must be located in the same namespace

Deploy the cluster-manager

Note:

  • The image version is defined in these resources as this allows to control the upgrade cycle
  • For all available default parameters refer to splunk-ansible default.yml.spec.md
cat <<EOF | kubectl apply -n splunk-operator -f -
---
apiVersion: enterprise.splunk.com/v4
kind: ClusterManager
metadata:
  name: example
  finalizers:
  - enterprise.splunk.com/delete-pvc
spec:
  defaults: |-
    splunk:
      site: site1
      multisite_master: localhost
      all_sites: site1,site2,site3
      multisite_replication_factor_origin: 1
      multisite_replication_factor_total: 2
      multisite_search_factor_origin: 1
      multisite_search_factor_total: 2
      idxc:
        search_factor: 2
        replication_factor: 2
      # Apps defined here are deployed to the indexers of all the sites
      apps_location:
        - "https://example.com/splunk-apps/app3.tgz"
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: failure-domain.beta.kubernetes.io/zone
            operator: In
            values:
            - zone-1a
EOF

Deploy the indexer sites

cat <<EOF | kubectl apply -n splunk-operator -f -
---
apiVersion: enterprise.splunk.com/v4
kind: IndexerCluster
metadata:
  name: example-site1
  finalizers:
  - enterprise.splunk.com/delete-pvc
spec:
  replicas: 2
  clusterManagerRef:
    name: example
  defaults: |-
    splunk:
      multisite_master: splunk-example-cluster-manager-service
      site: site1
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: failure-domain.beta.kubernetes.io/zone
            operator: In
            values:
            - zone-1a
EOF

Create IndexerCluster CR for each required site with zone affinity specified as needed

Note:

  • The value of label for zone i.e. zone-1a for label failure-domain.beta.kubernetes.io/zone is specific to each cloud provider and should be changed based on the cloud provider you are using
  • Starting in Kubernetes v1.17, the label failure-domain.beta.kubernetes.io/zone is deprecated in favor of topology.kubernetes.io/zone. See the official documentation

Connecting a search-head cluster to a multisite indexer-cluster

Search head clusters do not have site awareness for artifact replication, so mapping Splunk sites to Kubernetes zones is not relevant in that context.

SearchHeadCluster resources can be connected to a multisite indexer cluster the same way as for single site. The name of the IndexerCluster part containing the cluster manager must be referenced in parameter clusterManagerRef.

Additional ansible default parameters must be set to activate multisite:

cat <<EOF | kubectl apply -n splunk-operator -f -
---
apiVersion: enterprise.splunk.com/v4
kind: SearchHeadCluster
metadata:
  name: example
  finalizers:
  - enterprise.splunk.com/delete-pvc
spec:
  replicas: 3
  image: "splunk/splunk:9.1.3"
  clusterManagerRef:
    name: example
  defaults: |-
    splunk:
      multisite_master: splunk-example-cluster-manager-service
      site: site0
EOF