hello-world-go

Sample Function Go

Prerequisites

OpenFunction

You can refer to the Installation Guide to setup OpenFunction.

Run it locally

Build the function locally

pack build func-helloworld-go --builder openfunction/builder-go:v2.4.0-1.17 --env FUNC_NAME="HelloWorld"  --env FUNC_CLEAR_SOURCE=true

Run the function

docker run --rm --env="FUNC_CONTEXT={\"name\":\"HelloWorld\",\"version\":\"v1.0.0\",\"port\":\"8080\",\"runtime\":\"Knative\"}" --env="CONTEXT_MODE=self-host" --name func-helloworld-go -p 8080:8080 func-helloworld-go

Send a request

curl http://localhost:8080/OpenFunction
# Hello, OpenFunction!

Deployment

1. Create secret

Generate a secret to access your container registry, such as one on Docker Hub or Quay.io. You can create this secret by editing the REGISTRY_SERVER, REGISTRY_USER and REGISTRY_PASSWORD fields in following command, and then run it.

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

2. Create function

   For sample function below, modify the spec.image field in function-sample.yaml to your own container registry address:

   apiVersion: core.openfunction.io/v1beta1
   kind: Function
   metadata:
     name: function-sample
   spec:
     image: "<your registry name>/sample-go-func:v1"

   Use the following command to create this Function:

   kubectl apply -f function-sample.yaml

3. Access function

   You can observe the process of a function with the following command:

   kubectl get functions.core.openfunction.io
   
   NAME              BUILDSTATE   SERVINGSTATE   BUILDER         SERVING         ADDRESS                                                         AGE
   function-sample   Succeeded    Running        builder-jgnzp   serving-q6wdp   http://function-sample.default.svc.cluster.local/               22m

   The Function.status.addresses field provides various methods for accessing functions. Get Function addresses by running following command:

   kubectl get function function-sample -o=jsonpath='{.status.addresses}'

   You will get the following address:

   [{"type":"External","value":"http://function-sample.default.ofn.io/"},
   {"type":"Internal","value":"http://function-sample.default.svc.cluster.local/"}]

   You can use the following command to create a pod in the cluster and access the function from the pod:

   kubectl run curl --image=radial/busyboxplus:curl -i --tty

   Access functions by the internal address:

   [ root@curl:/ ]$ curl http://function-sample.default.svc.cluster.local/OpenFunction
   Hello, OpenFunction!

   Access functions by the external address:

   To access the function via the Address of type External in Funtion.status, you should configure local domain first, see Configure Local Domain.

   [ root@curl:/ ]$ curl http://function-sample.default.ofn.io/World
   Hello, World!

   There is also an alternative way to trigger the function via the access address provided by the Knative Services:

   kubectl get ksvc
    
   NAME                       URL                                                            LATESTCREATED                   LATESTREADY                     READY   REASON
   serving-q6wdp-ksvc-wk6mv   http://serving-q6wdp-ksvc-wk6mv.default.<external-ip>.sslip.io   serving-q6wdp-ksvc-wk6mv-v100   serving-q6wdp-ksvc-wk6mv-v100   True

   Or get the service address directly with the following command:

   where<external-ip>indicates the external address of your gateway service.

   You can do a simple configuration to use the node ip as the <external-ip> as follows (Assuming you are using Kourier as network layer of Knative). Where 1.2.3.4 can be replaced by your node ip.

   kubectl patch svc -n kourier-system kourier \
     -p '{"spec": {"type": "LoadBalancer", "externalIPs": ["1.2.3.4"]}}'
   
   kubectl patch configmap/config-domain -n knative-serving \
     --type merge --patch '{"data":{"1.2.3.4.sslip.io":""}}'

   kubectl get ksvc serving-q6wdp-ksvc-wk6mv -o jsonpath={.status.url}
    
   http://serving-q6wdp-ksvc-wk6mv.default.<external-ip>.sslip.io

   Access the above service address via commands such as curl:

   curl http://serving-q6wdp-ksvc-wk6mv.default.<external-ip>.sslip.io/World
    
   Hello, World!
   
   curl http://serving-q6wdp-ksvc-wk6mv.default.<external-ip>.sslip.io/OpenFunction
    
   Hello, OpenFunction!