Add support for custom sidecars

[Mike Deeks (mdeeks)]

Customers can run optional sidecar containers alongside the API and Brainstore pods (e.g. OpenTelemetry collector for metrics routing to prometheus). The chart supports both extra containers and extra volumes so sidecars can mount config (ConfigMaps, Secrets, etc.).

Values

• api.extraContainers / api.extraVolumes
• brainstore.reader.extraContainers / brainstore.reader.extraVolumes
• brainstore.writer.extraContainers / brainstore.writer.extraVolumes

Example:

api:
  extraContainers:
    - name: otel-collector
      image: otel/opentelemetry-collector-contrib:0.100.0
      args:
        - --config=/etc/otel/config.yaml
      ports:
        - containerPort: 4318  # OTLP HTTP
      volumeMounts:
        - name: otel-config
          mountPath: /etc/otel
          readOnly: true
  extraVolumes:
    - name: otel-config
      configMap:
        name: otel-collector-config