从hello world到简单的CRUD后台框架

1. 构建一个简单的go工程

$ mkdir web_backend_simple
// 初始化 git
$ git init
// 使用 gomod 管理依赖
$ go mod init github.com/slimhappy/web_backend_simple
// 新建 mian.go
$ touch main.go

2. Hello World 代码

package main
	
import "fmt"

func main() {
    fmt.Println("hello world")
}

3. 编译并运行 Hello World 代码

$ go build main.go
$ ./mian
hello world

4. 下载gin框架

$ go get -u github.com/gin-gonic/gin
go: downloading github.com/gin-gonic/gin v1.7.7
go: github.com/gin-gonic/gin upgrade => v1.7.7
...//省略一堆的依赖下载

5. 参考gin的官方文档新建一个简单返回的接口

package main

import "github.com/gin-gonic/gin"

func main() {
	r := gin.Default()
	r.GET("/ping", func(c *gin.Context) {
		c.JSON(200, gin.H{
			"message": "pong",
		})
	})
	r.Run() // listen and serve on 0.0.0.0:8080 (for windows "localhost:8080")
}

编译并运行

$ go build main.go
$ ./mian
[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /ping                     --> main.main.func1 (3 handlers)
[GIN-debug] [WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.
Please check https://pkg.go.dev/github.com/gin-gonic/gin#readme-don-t-trust-all-proxies for details.
[GIN-debug] Environment variable PORT is undefined. Using port :8080 by default
[GIN-debug] Listening and serving HTTP on :8080

这里居然有一个WARNING！

[GIN-debug] [WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.
Please check https://pkg.go.dev/github.com/gin-gonic/gin#readme-don-t-trust-all-proxies for details.

不慌不慌，我们打开这个参考页面，并且得到解决方法，在代码里加上：

	r.SetTrustedProxies(nil)

6. 配置文件

6.1 配置文件的重要性

对于公开的仓库，隐去初始化的重要信息
便于平台部署，例如使用k8s的config map进行挂载

$ mkdir config
$ touch config.go

6.2 配置文件库的选择

$ go get github.com/spf13/viper