00:01

Lab: HTTP Trigger MQTT Bindings

current

Sample Function

Another plain forwarder

// Standard Express style HTTP sync function
export const tryKnative = (req, res) => {
  res.send(`Hello, ${req.query.u || 'World'}!`);
};

// OpenFunction standard function which could 
// set bridge between sync and async function
export const tryKnativeAsync = async (ctx, data) => {
  console.log('Data received: %o', data);

  // Forward HTTP body to Dapr outputs
  await ctx.send(data);

  // Send something back as HTTP response 
  // when necessary
  // ctx.res.send(data);
};

Remember to build the function, either when applying Function CR manifest or directly via Pack CLI tool

Sample CR Manifest

Check out full content in http-trigger.yml

spec:
  image: '<image-repo>/<image-name>:<image-tag>'
  serving:
    runtime: knative
    params:
      FUNCTION_TARGET: tryKnativeAsync
      FUNCTION_SIGNATURE_TYPE: openfunction
    outputs:
      - name: mqtt-output
        component: mqtt-out
        operation: create
    bindings:
      mqtt-out:
        type: bindings.mqtt
        version: v1
        metadata:
          - name: consumerID
            value: '{uuid}'
          - name: url
            value: tcp://admin:public@emqx:1883
          - name: topic
            value: out

OpenFunction 203

Triggering Async Function From HTTP Request

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Haili Zhang

KubeSphere Ambassador, CNCF OpenFunction TOC Memeber.
Cloud Platform Director of UISEE© Technology.
Cloud Native focuses: Kubernetes, DevOps, Observability, Service Mesh, Serverless.

webup

zhanghaili0610

haili.zhang@uisee.com

ServiceUP · 语雀

Table of Content

Tricky Part of Async Func

Pros

By leveraging Dapr, async function could nearly connect with everthing …
Check Dapr Bindings
Check Dapr PubSub Brokers

Cons

NEED events to pull the trigger
- Usually coming in from external systems, or interface with external systems
- e.g. message queue, cron, K8s events
Also rather unfriendly for testing
- We need a MQTT client tool to serve as the event publisher, remember that?

HTTP Comes to the Rescue

Idea

Use HTTP sync function as trigger
- POST data to one sync function
- Sync function bridge data to event hub
- With async function subscribed to hub

Solution

Enable Dapr output binding and pub in sync function runtime ^[1]
Check the figure aside as an example 👉

Feature introduced in OpenFunction 0.6.0 along with Node.js Function Framework 0.5.0 ↩︎

Invoke Async in A Sync Way!

Same function signature

Exactly the same async function signature.

function (ctx, data) {}

data: Request body data, parsed as JSON by default

Extensions

ctx.req: The pass-through Express standard HTTP request object
ctx.res: The pass-through Express standard HTTP response object
These two methods are optional for use, even no response made by ctx.res would NOT block the HTTP request handler

Specific signature type

New type openfunction ready to work.

OpenFunction Function CRD:

apiVersion: core.openfunction.io/v1beta1
kind: Function
metadata:
  name: func-name
spec:
  serving:
    # default to knative
    runtime: knative
    params:
      # default to http
      FUNCTION_SIGNATURE_TYPE: openfunction

CLI: --signature-type=openfunction
ENV: FUNCTION_SIGNATURE_TYPE=openfunction

Lab: HTTP Trigger MQTT Bindings

Sample Function

Another plain forwarder

// Standard Express style HTTP sync function
export const tryKnative = (req, res) => {
  res.send(`Hello, ${req.query.u || 'World'}!`);
};

// OpenFunction standard function which could 
// set bridge between sync and async function
export const tryKnativeAsync = async (ctx, data) => {
  console.log('Data received: %o', data);

  // Forward HTTP body to Dapr outputs
  await ctx.send(data);

  // Send something back as HTTP response 
  // when necessary
  // ctx.res.send(data);
};

Remember to build the function, either when applying Function CR manifest or directly via Pack CLI tool

Sample CR Manifest

Check out full content in http-trigger.yml

spec:
  image: '<image-repo>/<image-name>:<image-tag>'
  serving:
    runtime: knative
    params:
      FUNCTION_TARGET: tryKnativeAsync
      FUNCTION_SIGNATURE_TYPE: openfunction
    outputs:
      - name: mqtt-output
        component: mqtt-out
        operation: create
    bindings:
      mqtt-out:
        type: bindings.mqtt
        version: v1
        metadata:
          - name: consumerID
            value: '{uuid}'
          - name: url
            value: tcp://admin:public@emqx:1883
          - name: topic
            value: out

Deploy Sample Function

Apply function manifest, and check running states

$ kubectl apply -f http-trigger.yaml
function.core.openfunction.io/sample-node-http-trigger created

$ kubectl get fn
NAME                         BUILDSTATE   SERVINGSTATE   BUILDER   SERVING         URL                                                         AGE
sample-node-http-trigger     Skipped      Running                  serving-7d75d   http://openfunction.io/default/sample-node-http-trigger     6d

$ kubectl get deploy
NAME                                       READY   UP-TO-DATE   AVAILABLE   AGE
...
serving-7d75d-ksvc-xn768-v200-deployment   0/0     0            0           6d14h
...

Knative runtime would autoscale the deployment replica to 0, if no incoming request for a period of time.

HTTP~ Fire!

Send request to domain ingress.

POST data to target function URL:

curl -d '{"hello":"ofn"}' \
     -H 'Content-Type: application/json' \
     http://openfunction.io/default/sample-node-http-trigger

Wait a second (may be few more seconds for cold start), you would get results:
- From terminal: {"hello":"ofn"}
- From MQTT X ^[1] desktop client 👉

See also: OpenFunction 202 - Set up MQTT Broker ↩︎

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