Prerequisites

Registry Credential

When building a function, you’ll need to push your function container image to a container registry like Docker Hub or Quay.io. To do that you’ll need to generate a secret for your container registry first.

You can create this secret by filling in the REGISTRY_SERVER, REGISTRY_USER and REGISTRY_PASSWORD fields, and then run the following command.

REGISTRY_SERVER=https://index.docker.io/v1/
REGISTRY_USER=<your_registry_user>
REGISTRY_PASSWORD=<your_registry_password>
kubectl create secret docker-registry push-secret \
 --docker-server=$REGISTRY_SERVER \
 --docker-username=$REGISTRY_USER \
 --docker-password=$REGISTRY_PASSWORD

Source repository Credential

If your source code is in a private git repository, you’ll need to create a secret containing the private git repo’s username and password:

USERNAME=<your_git_username>
PASSWORD=<your_git_password>
kubectl create secret generic git-repo-secret \
 --username=$USERNAME \
 --password=$USERNAME

You can then reference this secret in the Function CR’s spec.build.srcRepo.credentials

apiVersion: core.openfunction.io/v1beta1
kind: Function
metadata:
  name: function-sample
spec:
  version: "v2.0.0"
  image: "openfunctiondev/sample-go-func:v1"
  imageCredentials:
    name: push-secret
  port: 8080 # default to 8080
  build:
    builder: openfunction/builder-go:latest
    env:
      FUNC_NAME: "HelloWorld"
      FUNC_CLEAR_SOURCE: "true"
    srcRepo:
      url: "https://github.com/OpenFunction/samples.git"
      sourceSubPath: "functions/knative/hello-world-go"
      revision: "main"
      credentials:
         name: git-repo-secret
  serving:
    template:
      containers:
        - name: function # DO NOT change this
          imagePullPolicy: IfNotPresent 
    runtime: "knative"

Kafka

Async functions can be triggered by events in message queues like Kafka, here you can find steps to setup a Kafka cluster for demo purpose.

  1. Install strimzi-kafka-operator in the default namespace.

    helm repo add strimzi https://strimzi.io/charts/
    helm install kafka-operator -n default strimzi/strimzi-kafka-operator
    
  2. Run the following command to create a Kafka cluster and Kafka Topic in the default namespace. The Kafka and Zookeeper clusters created by this command have a storage type of ephemeral and are demonstrated using emptyDir.

    Here we create a 1-replica Kafka server named <kafka-server> and a 1-replica topic named <kafka-topic> with 10 partitions

    cat <<EOF | kubectl apply -f -
    apiVersion: kafka.strimzi.io/v1beta2
    kind: Kafka
    metadata:
      name: <kafka-server>
      namespace: default
    spec:
      kafka:
        version: 3.3.1
        replicas: 1
        listeners:
          - name: plain
            port: 9092
            type: internal
            tls: false
          - name: tls
            port: 9093
            type: internal
            tls: true
        config:
          offsets.topic.replication.factor: 1
          transaction.state.log.replication.factor: 1
          transaction.state.log.min.isr: 1
          default.replication.factor: 1
          min.insync.replicas: 1
          inter.broker.protocol.version: "3.1"
        storage:
          type: ephemeral
      zookeeper:
        replicas: 1
        storage:
          type: ephemeral
      entityOperator:
        topicOperator: {}
        userOperator: {}
    ---
    apiVersion: kafka.strimzi.io/v1beta2
    kind: KafkaTopic
    metadata:
      name: <kafka-topic>
      namespace: default
      labels:
        strimzi.io/cluster: <kafka-server>
    spec:
      partitions: 10
      replicas: 1
      config:
        cleanup.policy: delete
        retention.ms: 7200000
        segment.bytes: 1073741824
    EOF
    
  3. Run the following command to check Pod status and wait for Kafka and Zookeeper to run and start.

    $ kubectl get po
    NAME                                              READY   STATUS        RESTARTS   AGE
    <kafka-server>-entity-operator-568957ff84-nmtlw   3/3     Running       0          8m42s
    <kafka-server>-kafka-0                            1/1     Running       0          9m13s
    <kafka-server>-zookeeper-0                        1/1     Running       0          9m46s
    strimzi-cluster-operator-687fdd6f77-cwmgm         1/1     Running       0          11m
    

    Run the following command to view the metadata for the Kafka cluster.

    $ kafkacat -L -b <kafka-server>-kafka-brokers:9092