Configure a custom values file for ScalarDB Cluster

This document explains how to create your custom values file for the ScalarDB Cluster chart. For details on the parameters, see the README of the ScalarDB Cluster chart.

Required configurations

Image configurations

You must set scalardbCluster.image.repository. Be sure to specify the ScalarDB Cluster container image so that you can pull the image from the container repository.

scalardbCluster:
  image:
    repository: <SCALARDB_CLUSTER_CONTAINER_IMAGE>

Database configurations

You must set scalardbCluster.scalardbClusterNodeProperties. Please set scalardb-cluster-node.properties to this parameter. For more details on the configurations of ScalarDB Cluster, see ScalarDB Cluster Configurations.

scalardbCluster:
  scalardbClusterNodeProperties: |
    scalar.db.cluster.membership.type=KUBERNETES
    scalar.db.cluster.membership.kubernetes.endpoint.namespace_name=${env:SCALAR_DB_CLUSTER_MEMBERSHIP_KUBERNETES_ENDPOINT_NAMESPACE_NAME}
    scalar.db.cluster.membership.kubernetes.endpoint.name=${env:SCALAR_DB_CLUSTER_MEMBERSHIP_KUBERNETES_ENDPOINT_NAME}
    scalar.db.contact_points=localhost
    scalar.db.username=${env:SCALAR_DB_USERNAME}
    scalar.db.password=${env:SCALAR_DB_PASSWORD}
    scalar.db.storage=cassandra

Note that you must always set the following three properties if you deploy ScalarDB Cluster in a Kubernetes environment by using Scalar Helm Chart. These properties are fixed values. Since the properties don't depend on individual environments, you can set the same values by copying the following values and pasting them in scalardbCluster.scalardbClusterNodeProperties.

scalardbCluster:
  scalardbClusterNodeProperties: |
    scalar.db.cluster.membership.type=KUBERNETES
    scalar.db.cluster.membership.kubernetes.endpoint.namespace_name=${env:SCALAR_DB_CLUSTER_MEMBERSHIP_KUBERNETES_ENDPOINT_NAMESPACE_NAME}
    scalar.db.cluster.membership.kubernetes.endpoint.name=${env:SCALAR_DB_CLUSTER_MEMBERSHIP_KUBERNETES_ENDPOINT_NAME}

Optional configurations

Resource configurations (recommended in production environments)

To control pod resources by using requests and limits in Kubernetes, you can use scalardbCluster.resources.

Note that, for commercial licenses, the resources for each pod of Scalar products are limited to 2vCPU / 4GB memory. Also, if you use the pay-as-you-go containers that the AWS Marketplace provides, you will not be able to run any containers that exceed the 2vCPU / 4GB memory configuration in resources.limits. If you exceed this resource limitation, the pods will automatically stop.

You can configure requests and limits by using the same syntax as requests and limits in Kubernetes. For more details on requests and limits in Kubernetes, see Resource Management for Pods and Containers.

scalardbCluster:
  resources:
    requests:
      cpu: 2000m
      memory: 4Gi
    limits:
      cpu: 2000m
      memory: 4Gi

Secret configurations (recommended in production environments)

To use environment variables to set some properties (e.g., credentials) in scalardbCluster.scalardbClusterNodeProperties, you can use scalardbCluster.secretName to specify the Secret resource that includes some credentials.

For example, you can set credentials for a backend database (scalar.db.username and scalar.db.password) by using environment variables, which makes your pods more secure.

For more details on how to use a Secret resource, see How to use Secret resources to pass the credentials as the environment variables into the properties file.

scalardbCluster:
  secretName: "scalardb-cluster-credentials-secret"

Affinity configurations (recommended in production environments)

To control pod deployment by using affinity and anti-affinity in Kubernetes, you can use scalardbCluster.affinity.

You can configure affinity and anti-affinity by using the same syntax for affinity and anti-affinity in Kubernetes. For more details on configuring affinity in Kubernetes, see Assigning Pods to Nodes.

scalardbCluster:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - podAffinityTerm:
            labelSelector:
              matchExpressions:
                - key: app.kubernetes.io/name
                  operator: In
                  values:
                    - scalardb-cluster
                - key: app.kubernetes.io/app
                  operator: In
                  values:
                    - scalardb-cluster
            topologyKey: kubernetes.io/hostname
          weight: 50

Prometheus and Grafana configurations (recommended in production environments)

To monitor ScalarDB Cluster pods by using kube-prometheus-stack, you can set scalardbCluster.grafanaDashboard.enabled, scalardbCluster.serviceMonitor.enabled, and scalardbCluster.prometheusRule.enabled to true. When you set these configurations to true, the chart deploys the necessary resources and kube-prometheus-stack starts monitoring automatically.

scalardbCluster:
  grafanaDashboard:
    enabled: true
    namespace: monitoring
  serviceMonitor:
    enabled: true
    namespace: monitoring
    interval: 15s
  prometheusRule:
    enabled: true
    namespace: monitoring

SecurityContext configurations (default value is recommended)

To set SecurityContext and PodSecurityContext for ScalarDB Cluster pods, you can use scalardbCluster.securityContext and scalardbCluster.podSecurityContext.

You can configure SecurityContext and PodSecurityContext by using the same syntax as SecurityContext and PodSecurityContext in Kubernetes. For more details on the SecurityContext and PodSecurityContext configurations in Kubernetes, see Configure a Security Context for a Pod or Container.

scalardbCluster:
  podSecurityContext:
    seccompProfile:
      type: RuntimeDefault
  securityContext:
    capabilities:
      drop:
        - ALL
    runAsNonRoot: true
    allowPrivilegeEscalation: false

TLS configurations (optional based on your environment)

You can enable TLS in all ScalarDB Cluster connections by using the following configurations:

scalardbCluster:
  scalardbClusterNodeProperties: |
    ...(omit)...
    scalar.db.cluster.tls.enabled=true
    scalar.db.cluster.tls.ca_root_cert_path=/tls/certs/ca-root-cert.pem
    scalar.db.cluster.node.tls.cert_chain_path=/tls/certs/cert-chain.pem
    scalar.db.cluster.node.tls.private_key_path=/tls/certs/private-key.pem
    scalar.db.cluster.tls.override_authority=cluster.scalardb.example.com
  tls:
    enabled: true
    overrideAuthority: "cluster.scalardb.example.com"
    caRootCertSecret: "scalardb-cluster-tls-ca"
    certChainSecret: "scalardb-cluster-tls-cert"
    privateKeySecret: "scalardb-cluster-tls-key"

In this case, you have to create secret resources that include private key and certificate files for ScalarDB Cluster as follows:

kubectl create secret generic scalardb-cluster-tls-ca --from-file=ca-root-cert=/path/to/your/ca/certificate/file -n <NAMESPACE>
kubectl create secret generic scalardb-cluster-tls-cert --from-file=cert-chain=/path/to/your/certificate/file -n <NAMESPACE>
kubectl create secret generic scalardb-cluster-tls-key --from-file=private-key=/path/to/your/private/key/file -n <NAMESPACE>

For more details on how to prepare private key and certificate files, see How to create private key and certificate files for Scalar products.

Also, you can set the custom authority for TLS communication by using scalardbCluster.tls.overrideAuthority. This value doesn't change what host is actually connected. This value is intended for testing but may safely be used outside of tests as an alternative to DNS overrides. For example, you can specify the hostname presented in the certificate chain file that you set by using scalardbCluster.tls.certChainSecret. This chart uses this value for startupProbe and livenessProbe.

Replica configurations (optional based on your environment)

You can specify the number of ScalarDB Cluster replicas (pods) by using scalardbCluster.replicaCount.

scalardbCluster:
  replicaCount: 3

Logging configurations (optional based on your environment)

To change the ScalarDB Cluster log level, you can use scalardbCluster.logLevel.

scalardbCluster:
  logLevel: INFO

GraphQL configurations (optional based on your environment)

To use the GraphQL feature in ScalarDB Cluster, you can set scalardbCluster.graphql.enabled to true to deploy some resources for the GraphQL feature. Note that you also need to set scalar.db.graphql.enabled=true in scalardbCluster.scalardbClusterNodeProperties when using the GraphQL feature.

scalardbCluster:
  graphql:
    enabled: true

Also, you can configure the Service resource that accepts GraphQL requests from clients.

scalardbCluster:
  graphql:
    service:
      type: ClusterIP
      annotations: {}
      ports:
        graphql:
          port: 8080
          targetPort: 8080
          protocol: TCP

SQL configurations (optional based on your environment)

To use the SQL feature in ScalarDB Cluster, there is no configuration necessary for custom values files. You can use the feature by setting scalar.db.sql.enabled=true in scalardbCluster.scalardbClusterNodeProperties.

Scalar Envoy configurations (optional based on your environment)

To use ScalarDB Cluster with indirect mode, you must enable Envoy as follows.

envoy:
  enabled: true

Also, you must set the Scalar Envoy configurations in the custom values file for ScalarDB Cluster. This is because clients need to send requests to ScalarDB Cluster via Scalar Envoy as the load balancer of gRPC requests if you deploy ScalarDB Cluster in a Kubernetes environment with indirect mode.

For more details on Scalar Envoy configurations, see Configure a custom values file for Scalar Envoy.

envoy:
  configurationsForScalarEnvoy: 
    ...

scalardbCluster:
  configurationsForScalarDbCluster: 
    ...

Taint and toleration configurations (optional based on your environment)

If you want to control pod deployment by using the taints and tolerations in Kubernetes, you can use scalardbCluster.tolerations.

You can configure taints and tolerations by using the same syntax as the tolerations in Kubernetes. For details on configuring tolerations in Kubernetes, see the official Kubernetes documentation Taints and Tolerations.

scalardbCluster:
  tolerations:
    - effect: NoSchedule
      key: scalar-labs.com/dedicated-node
      operator: Equal
      value: scalardb-cluster