Golang development: environment articles (seven) use of Go mod

Glide works well, why use Modules

In Go 1.11, the official package management tool was added, called Go Modules. Before the Go mod appeared, the most commonly used package managers were government, glide, etc. These tools did not meet Go's expectations for package management, such as each download, such as off-wall download, such as dependence on GOPATH, such as multiple versions Control, etc. Then Go Modules appeared, it does not depend on GOPATH, it is only related to the project, you can specify an agent, you can easily control by version, get rid of the dependence of GOPATH, and laid the foundation for the future development of Go.

Use Go mod command to manage packages

command	description
go init	Initialize the mod under the current directory item
go tidy	Pull dependent modules and remove unused modules
go vendor	Copy dependencies to vendor
go edit	Edit go.mod
go verify	Verify correct dependencies

In fact, basically using init and tidy is enough.

Set environment variables

GO111MODULE
has three values, off, on, auto, off and on are off and on, auto will judge whether to use the modules function according to whether there is a go.mod file in the current directory. No matter which mode is used, the module function does not search for dependent files in the GOPATH directory by default.
GOPROXY
sets up a proxy service, https://goproxy.io . You can also set up a proxy service yourself, and then set GOPROXY as the proxy server address.
vim ~ / .bash_profile
added two lines of configuration
export GO111MODULE = on
export GOPROXY = https: //goproxy.io

source ~/.bash_profile

Give a chestnut

Create project myproject
main.go

package main

import (
	"github.com/satori/go.uuid"
	"fmt"
)

func main() {
	uid := uuid.NewV4()
	fmt.Println(uid)
}

Execute Go mod command, init and tidy

go mod init
go: creating new go.mod: module myproject

go mod tidy
go: finding golang.org/x/tools latest
go: downloading golang.org/x/tools v0.0.0-20200415034506-5d8e1897c761
go: extracting golang.org/x/tools v0.0.0-20200415034506-5d8e1897c761
go: finding gopkg.in/check.v1 latest
go: downloading gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f
go: extracting gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f
go: finding github.com/niemeyer/pretty latest
go: downloading github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e
go: extracting github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e
go: downloading github.com/kr/text v0.1.0
go: extracting github.com/kr/text v0.1.0

Compile execution result

go build main.go
./main
6723138d-ab2c-4de6-b996-732362985548

You can see the main file go.mod generated by Go mod

cat go.mod
module myproject

go 1.13

require (
	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
	github.com/satori/go.uuid v1.2.0
	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
)

Each package is followed by a version. If you want to switch branches, later versions can be arbitrarily switched to the required branch, such as

require (
	github.com/niemeyer/pretty master
	github.com/satori/go.uuid v1.2.0
	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
)

You can also use local code to replace remote code branches. You can use the following
/data/www/go/src/go.uuid instead of the remote branch github.com/satori/go.uuid.
Add the following code to the last line of go.mod

replace github.com/satori/go.uuid => /data/www/go/src/go.uuid 

The use of Go mod is not particularly simple.