Developing an HTTP Function Using Go

Constraints

• HTTP functions can only use APIG or APIC triggers.

  According to the forwarding protocol between FunctionGraph and APIG/APIC, a valid HTTP function response must contain body(String), statusCode(int), headers(Map), and isBase64Encoded(boolean). By default, the response is encoded using Base64. The default value of isBase64Encoded is true. The same applies to other frameworks. For details, see Base64 Decoding and Return Structure.

• By default, port 8000 is enabled for HTTP functions.
• Table 13 describes the context methods provided by FunctionGraph.

Example of Using Go to Develop an HTTP Function

Overview

Since HTTP functions do not directly support Go code deployment, this chapter provides an example of using binary conversion to deploy a Go program on FunctionGraph.

Procedure

For details, see Building an HTTP Function with Go.

Sample Code

The code of the source file main.go is as follows:

// main.go
package main

import (
	"fmt"
	"net/http"

	"github.com/emicklei/go-restful"
)

func registerServer() {
	fmt.Println("Running a Go Http server at localhost:8000/")

	ws := new(restful.WebService)
	ws.Path("/")

	ws.Route(ws.GET("/hello").To(Hello))
	c := restful.DefaultContainer
	c.Add(ws)
	fmt.Println(http.ListenAndServe(":8000", c))
}

func Hello(req *restful.Request, resp *restful.Response) {
	resp.Write([]byte("nice to meet you"))
}

func main() {
	registerServer()
}

# bootstrap
/opt/function/code/go-http-demo

In main.go, an HTTP server is started using port 8000, and an API whose path is /hello is registered. When the API is invoked, "nice to meet you" is returned.

Compiling and Packaging

1. On the Linux server, compile the preceding code using the go build -o go-http-demo main.go command.
2. Compress go-http-demo and bootstrap into a ZIP package named xxx.zip.

Creating an HTTP Function

Create an HTTP function in FunctionGraph, and upload the xxx.zip code package.

Creating an APIG Trigger

Create an APIG trigger, select a proper group and environment, and click OK. (You can select None for Security Authentication in the test phase.)

Figure 1 Copying the URL

Invocation Test

Copy the URL generated in Creating an APIG Trigger + Path registered in the code + /hello to the address box of the browser. The following information is displayed:

Figure 2 Returned result