damiannolan / eventing-init

A K8s Init Container as a wait mechanism for Kafka availability and Topic configuration

eventing-init

A Kubernetes Init Container as a wait mechanism for Kafka availability and topic configuration.

This project serves as a means to block service startup until Kafka eventing and topic dependencies have been fulfilled.

Usage

The following example assumes the use of Helm (A Package manager for Kubernetes), however this is not a requirement and appropriate K8s manifests can be constructed without the use of Helm's templating functionality.

1. A ConfigMap should be provided with the required Kafka Topics. For Example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: service-x-topics-config
data:
  topics.yml: |
    topics:
    {{- range .Values.kafka.topics }}
      - {{ . | quote }}
    {{- end }}

2. Topic entries should be supplied through values.yaml For Example:

...
kafka:
  topics:
    - notification-events
    - request-events

3. An initContainers entry should be added to the service Deployment PodSpec with a volumeMounts entry specifying the associated ConfigMap. Environment variables can be provided in the Container spec, if omitted the default configuration fallbacks are used for Kafka host, port and version.

For Example:

spec:
    initContainers:
    - name: eventing-init
      image: damiannolan/eventing-init:0.1.0
      imagePullPolicy: Always
      volumeMounts:
      - name: topics-config
        mountPath: /etc/config
    ...
    volumes:
    - name: topics-config
      configMap:
      name: sevice-x-topics-config

TODO's

• Cleanup config pkg - possibly use viper
• Add more configurability (Create topics if not exists option)
• Use logrus for logging
• Use testify for assertions