Quickstarts

• 1: Prerequisites
• 2: Create sync functions
• 3: Create async functions

1 - 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: 3.1.0
       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:
       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
   

2 - Create sync functions

Before you creating any functions, make sure you’ve installed all the prerequisites

Sync functions are funtions whose inputs are payloads of HTTP requests, and the output or response are sent to the waiting client immediately after the function logic finishes processing the inputs payload. Below you can find some sync function examples in different languages:

You can find more function samples here

3 - Create async functions

Before you creating any functions, make sure you’ve installed all the prerequisites

Async functions are event-driven and their inputs are usually events from Non-HTTP event sources like message queues, cron triggers, MQTT brokers etc. and usually the client will not wait for an immediate response after triggering an async function by delivering an event. Below you can find some async function examples in different languages:

You can find more function samples here