Polish the Golang demo with Gin web framework

demos/golang/README.md

@@ -1,20 +1,25 @@
 # Use Golang with Occlum
 
-This project demonstrates how Occlum enables [Golang](https://golang.org) programs running in SGX enclaves.
+This project demonstrates how Occlum enables [Golang](https://golang.org) programs running in SGX enclaves, the demo program is a HTTP web server based on a widely used web framework([Gin](https://gin-gonic.com)) for Go.
 
-Step 1: Build Golang web server program using the Occlum Golang toolchain(i.e., `occlum-go`)
+Step 1: Install Gin with `occlum-go`, it may take a few minutes
+```
+occlum-go get -u -v github.com/gin-gonic/gin
+```
+
+Step 2: Build the Golang web server using the Occlum Golang toolchain(i.e., `occlum-go`)
 ```
 occlum-go build -o web_server -buildmode=pie ./web_server.go
 ```
 
-Step 2: You can run the web server demo on Occlum via
+Step 3: You can run the web server demo on Occlum via
 ```
 ./run_golang_on_occlum.sh
 ```
 The HTTP web server should now start to listen on port 8090 and serve HTTP requests.
 
-Step 3: To check whether the HTTP server works, run
+Step 4: To check whether the HTTP server works, run
 ```
-curl http://127.0.0.1:8090/hello1
+curl http://127.0.0.1:8090/ping
 ```
-in another terminal, and get the response "hello,1".
+in another terminal, and get the response `{"message":"pong"}`.

demos/golang/run_golang_on_occlum.sh

@@ -16,8 +16,8 @@ fi
 rm -rf occlum_context && mkdir occlum_context
 cd occlum_context
 occlum init
-jq '.vm.user_space_size = "320MB"' Occlum.json > temp_Occlum.json
-jq '.process.default_mmap_size = "256MB"' temp_Occlum.json > Occlum.json
+jq '.vm.user_space_size = "380MB"' Occlum.json > temp_Occlum.json
+jq '.process.default_mmap_size = "300MB"' temp_Occlum.json > Occlum.json
 
 # 2. Copy program into Occlum Workspace and build
 cp ../web_server image/bin

demos/golang/web_server.go

@@ -1,29 +1,26 @@
 package main
 
-import "net/http"
-import "log"
-import "flag"
-import "fmt"
+import (
+    "io"
+    "os"
 
-type Controller struct {}
-func (c Controller)ServeHTTP(writer http.ResponseWriter, request *http.Request){
-    writer.Write([]byte("hello,1\n"));
-}
-
-func hello(writer http.ResponseWriter, request *http.Request) {
-    writer.Write([]byte("hello,2\n"));
-}
-
-var port string
-
-func init() {
-        flag.StringVar(&port, "port", "8090", "port number, default value is 8090")
-}
+    "github.com/gin-gonic/gin"
+)
 
 func main() {
-    flag.Parse()
-    fmt.Println("Web Server port is:", port)
-    http.Handle("/hello1",&Controller{})
-    http.Handle("/hello2",http.HandlerFunc(hello))
-    log.Fatal(http.ListenAndServe(":" + port, nil))
+    // Disable console color, you don't need console color when writing the logs to file.
+    gin.DisableConsoleColor()
+
+    // Use a file for logging
+    f, _ := os.Create("/root/gin.log")
+    gin.DefaultWriter = io.MultiWriter(f, os.Stdout)
+
+    r := gin.Default()
+    r.GET("/ping", func(c *gin.Context) {
+        c.JSON(200, gin.H{
+            "message": "pong",
+        })
+    })
+    // Listen and serve on 0.0.0.0:8090
+    r.Run(":8090")
 }