Many of the configuration options that are performed through hardware configuration, system commands or environment variables on traditional server platforms are now available through Helm properties. Most of these settings are listed in Section A.3, “Kubernetes Cluster Startup Options”.

One system setting that is not configurable through Kubernetes or Helm is whether the base platform has Transparent Huge Pages (THP) enabled or not. This is dependent of the memory management settings on the actual base hardware on which Kubernetes is hosted. Having THP enabled can cause problems with memory-intensive applications like VoltDB and it is strongly recommended that THP be disabled before starting your cluster. (See the section on Transparent Huge Pages in the VoltDB Administrator's Guide for an explanation of why this is an issue.)

If you are not managing the Kubernetes environment yourself or cannot get your provider to modify their environment, you will need to override VoltDB's warning about THP on startup by setting the cluster.clusterSpec.additionalArgs property to include the VoltDB start argument to disable the check for THP. For example:

cluster:
  clusterSpec:
    additionalStartArgs: 
      - "--ignore=thp"

In addition to configuring the environment VoltDB runs in, there are many different characteristics of the database itself you can control. These include mapping network interfaces and ports, selecting and configuring database features, and identifying the database schema, class files, and security settings.

The network settings are defined through the cluster.serviceSpec properties, where you can choose the individual ports and choose whether to expose them through the networking service (cluster.serviceSpec.type) you can also select. For example, the following YAML file disables exposure of the admin port and assigns the externalized client port to 31313:

cluster:
  serviceSpec:
    type: NodePort
      adminPortEnabled: false
      clientPortEnabled: true
      clientNodePort: 31313

The majority of the database configuration options for VoltDB are traditionally defined in an XML configuration file. When using Kubernetes, these options are declared using YAML and Helm properties.

In general, the Helm properties follow the same structure as the XML configuration, beginninging with "cluster.config". So, for example, where the number of sites per host is defined in XML as :

<deployment>
   <cluster sitesperhost="{n}"/>
</deployment>

It is defined in Kubernetes as:

cluster:
  config:
    deployment:
      cluster:
        sitesperhost: {n}

The following sections give examples of defining common database configurations options using both XML and YAML. See Section A.6, “VoltDB Database Configuration Options” for a complete list of the Helm properties available for configuring the database.

<commandlog enabled="true"
            synchronous="true"
            logsize="3072">
  <frequency time="300" 
             transactions="1000"/>
</commandlog>

cluster:
  config:
    deployment:
      commandlog:
        enabled: true
        synchronous: true
        logsize: 3072
        frequency:
          transactions 1000

<export>
  <configuration 
      target="eventlog" 
      type="file">
    <property 
       name="type">csv</property>
    <property 
       name="nonce">eventlog</property>
  </configuration>
</export>

cluster:
  config:
    deployment:
      export:
        configurations:
           - target: eventlog
             type: file
             properties:
                type: csv
                nonce: eventlog                 

<security enabled="true"/>
<users>
  <user name="admin" 
        password="superman" 
        roles="administrator"/>
  <user name="mitty" 
        password="thurber" 
        roles="user"/>
</users>

cluster:
  config:
    deployment:
      security:
        enabled: true
      users:
        - name: admin
          password: superman
          roles: administrator
        - name: mitty
          password: thurber
          roles: user
    auth:
      username: admin
      password: superman