[demos] Fix golang webserver build error

.github/workflows/demo_test.yml

@@ -82,8 +82,7 @@ jobs:
       run: docker exec ${{ github.job }} bash -c "cd /root/occlum/tools/toolchains/golang && ./build.sh go1.18.4_for_occlum && cd /root/occlum/demos/golang/go_sqlite/ && SGX_MODE=SIM ./run_go_sqlite_demo.sh"
 
     - name: Go Server set up and run
-      run: docker exec ${{ github.job }} bash -c "cd /root/occlum/demos/golang/web_server && occlum-go mod init web_server && occlum-go get -u -v github.com/gin-gonic/gin;
-            occlum-go build -o web_server ./web_server.go;
+      run: docker exec ${{ github.job }} bash -c "cd /root/occlum/demos/golang/web_server && ./build.sh;
             SGX_MODE=SIM ./run_golang_on_occlum.sh" &
 
     - name: Set up Golang grpc pingpong test

.github/workflows/hw_mode_test.yml

@@ -142,8 +142,7 @@ jobs:
 
     - name: Go server set up and run
       run: docker exec ${{ env.CONTAINER_NAME }} bash -c "export GO111MODULE=on;
-            cd /root/occlum/demos/golang/web_server && occlum-go mod init web_server && occlum-go get -u -v github.com/gin-gonic/gin;
-            occlum-go build -o web_server ./web_server.go;
+            cd /root/occlum/demos/golang/web_server && ./build.sh;
             ./run_golang_on_occlum.sh" &
 
     - name: Set up Golang grpc pingpong test

demos/golang/web_server/README.md

@@ -2,24 +2,18 @@
 
 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: Install Gin with `occlum-go`, it may take a few minutes
+Step 1: Install Gin and build Golang web server with `occlum-go`
 ```
-occlum-go mod init web_server && \
-occlum-go get -u -v github.com/gin-gonic/gin
+./build.sh
 ```
 
-Step 2: Build the Golang web server using the Occlum Golang toolchain(i.e., `occlum-go`)
-```
-occlum-go build -o web_server ./web_server.go
-```
-
-Step 3: You can run the web server demo on Occlum via
+Step 2: 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 4: To check whether the HTTP server works, run
+Step 3: To check whether the HTTP server works, run
 ```
 curl http://127.0.0.1:8090/ping
 ```

demos/golang/web_server/build.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+
+rm -f go.mod
+occlum-go mod init web_server
+occlum-go mod tidy
+occlum-go get -u -v github.com/gin-gonic/gin
+occlum-go get -u -v golang.org/x/crypto@v0.23.0
+
+occlum-go build -o web_server ./web_server.go