High Availability Kubecost

Note: High availability mode is only officially supported on Kubecost Enterprise plans.

Running Kubecost in high availability (HA) mode is a feature that relies on multiple Kubecost replica pods implementing the ETL Bucket Backup feature combined with a Leader/Follower implementation which ensures that there always exists exactly one leader across all replicas.

Leader + Follower

The Leader/Follower implementation leverages a coordination.k8s.io/v1 Lease resource to manage the election of a leader when necessary. To control access of the backup from the ETL pipelines, a RWStorageController is implemented to ensure the following:

  • Followers block on all backup reads, and poll bucket storage for any backup reads every 30 seconds.
  • Followers no-op on any backup writes.
  • Followers who receive Queries in a backup store will not stack on pending reads, preventing external queries from blocking.
  • Followers promoted to Leader will drop all locks and receive write privileges.
  • Leaders behave identically to a single Kubecost install.

Leader/Follower

Configuring high availability

In order to enable the leader/follower and HA features, the following must also be configured:

  • Replicas are set to a value greater than 1
  • ETL FileStore is Enabled (enabled by default)
  • ETL Bucket Backup is configured

For example, using our Helm chart, the following is an acceptable configuration:

helm install kubecost kubecost/cost-analyzer --namespace kubecost \
       --setkubecostDeployment.leaderFollower.enabled=true\
       --setkubecostDeployment.replicas=5 \
       --setkubecostModel.etlBucketConfigSecret=kubecost-bucket-secret

This can also be done in the values.yaml file within the chart:

kubecostModel:image:"gcr.io/kubecost1/cost-model"imagePullPolicy:Always# ...# ETL should be enabled with etlFileStoreEnabled: trueetl:trueetlFileStoreEnabled:true# ...# ETL Bucket Backup should be configured by passing the configuration secret nameetlBucketConfigSecret:kubecost-bucket-secret# Used for HA mode in Enterprise tierkubecostDeployment:# Select a number of replicas of Kubecost pods to runreplicas:5# Enable Leader/Follower ElectionleaderFollower:enabled:true