Merge pull request #265 from benjaminhuo/main

Add guide for dapr standalone mode

Author: benjaminhuo

README.md

@@ -1,5 +1,7 @@
 # OpenFunction Website
 
+[![Netlify Status](https://api.netlify.com/api/v1/badges/ecf7df22-21fe-4e32-8cae-fc62fb20dff5/deploy-status)](https://app.netlify.com/sites/openfunction-dev/deploys)
+
 openfunction.dev is OpenFunction's website which is built with [Hugo](https://gohugo.io/) and [Hugo template Docsy](https://github.com/google/docsy).
 
 ## Contribute

content/en/docs/concepts/baas_integration.md

@@ -0,0 +1,102 @@
+---
+title: "BaaS Integration"
+linkTitle: "BaaS Integration"
+weight: 3350
+description: 
+---
+
+One of the unique features of OpenFunction is its simple integration with various backend services (BaaS) through [Dapr](https://docs.dapr.io/concepts/components-concept/). Currently, OpenFunction supports Dapr [pub/sub](https://docs.dapr.io/reference/components-reference/supported-pubsub/) and [bindings](https://docs.dapr.io/reference/components-reference/supported-bindings/) building blocks, and more will be added in the future.
+
+In OpenFunction v0.7.0 and versions prior to v0.7.0, OpenFunction integrates with BaaS by injecting a dapr sidecar container into each function instance's pod, which leads to the following problems：
+
+- The entire function instance's launch time is slowed down by the launching of the dapr sidecar container.
+- The dapr sidecar container may consume more resources than the function container itself.
+
+To address the problems above, OpenFunction introduces the `Dapr Standalone Mode` in v0.8.0.
+
+## Dapr Standalone Mode
+
+In Dapr standalone mode, one `Dapr Proxy service` will be created for each function which is then shared by all instances of this function. This way, there is no need to launch a seperate Dapr sidecar container for each function instance anymore which reduces the function launching time significantly.
+
+<div align=center><img width="100%" height="100%" src=/images/docs/en/concepts/function/dapr_proxy.png/></div>
+
+## Choose the appropriate Dapr Service Mode
+
+So now you've 2 options to integrate with BaaS:
+
+- `Dapr Sidecar Mode`
+- `Dapr Standalone Mode`
+
+You can choose the appropriate Dapr Service Mode for your functions. The `Dapr Standalone Mode` is the recommened and default mode. You can use `Dapr Sidecar Mode` if your function doesn't scale frequently or you've difficulty to use the `Dapr Standalone Mode`.
+
+You can control how to integrate with BaaS with 2 flags, both can be set in function's `serving.spec.annotations`:
+
+- `openfunction.io/enable-dapr` can be set to `true` or `false`
+- `openfunction.io/dapr-service-mode` can be set to `standalone` or `sidecar`
+- When `openfunction.io/enable-dapr` is set to `true`, users can choose the `Dapr Service Mode` by setting `openfunction.io/dapr-service-mode` to `standalone` or `sidecar`.
+- When `openfunction.io/enable-dapr` is set to `false`, the value of `openfunction.io/dapr-service-mode` will be ignored and neither `Dapr Sidecar` nor `Dapr Proxy Service` will be launched. 
+
+There're default values for both of these two flags if they're not set.
+
+- The value of `openfunction.io/enable-dapr` will be set to `true` if it's not defined  in `serving.spec.annotations` and the function definition contains either `serving.spec.inputs` or `serving.spec.outputs`. Otherwise it will be set to `false`.
+- The default value of `openfunction.io/dapr-service-mode` is `standalone` if not set.
+
+Below you can find a function example to set these two flags:
+
+```yaml
+apiVersion: core.openfunction.io/v1beta1
+kind: Function
+metadata:
+  name: cron-input-kafka-output
+spec:
+  version: "v2.0.0"
+  image: openfunctiondev/cron-input-kafka-output:v1
+  imageCredentials:
+    name: push-secret
+  build:
+    builder: openfunction/builder-go:latest
+    env:
+      FUNC_NAME: "HandleCronInput"
+      FUNC_CLEAR_SOURCE: "true"
+    srcRepo:
+      url: "https://github.com/OpenFunction/samples.git"
+      sourceSubPath: "functions/async/bindings/cron-input-kafka-output"
+      revision: "main"
+  serving:
+    annotations:
+      openfunction.io/enable-dapr: "true"
+      openfunction.io/dapr-service-mode: "standalone"
+    template:
+      containers:
+        - name: function # DO NOT change this
+          imagePullPolicy: IfNotPresent 
+    runtime: "async"
+    inputs:
+      - name: cron
+        component: cron
+    outputs:
+      - name: sample
+        component: kafka-server
+        operation: "create"
+    bindings:
+      cron:
+        type: bindings.cron
+        version: v1
+        metadata:
+        - name: schedule
+          value: "@every 2s"
+      kafka-server:
+        type: bindings.kafka
+        version: v1
+        metadata:
+        - name: brokers
+          value: "kafka-server-kafka-brokers:9092"
+        - name: topics
+          value: "sample-topic"
+        - name: consumerGroup
+          value: "bindings-with-output"
+        - name: publishTopic
+          value: "sample-topic"
+        - name: authRequired
+          value: "false"
+```