Go:编译构建时 ldflags 变量注入
1.变量注入
Go在编译构建时,可以注入变量,例如:
package main
import "fmt"
var Version = "0.0.1"
func main() {
fmt.Println(Version)
}
case 1:不注入变量
$ go build -o main main.go
$ ./main
0.0.1
case 2:注入变量
$ go build -ldflags "-X main.Version=0.0.9" -o main main.go
$ ./main
0.0.9
可以观察到,在编译构建可执行文件时,通过命令,注入main包的Version变量值。
2.常用形式
在编译构建时注入变量,常常用于可执行文件版本等信息的构建。
举例如下:
2.1.目录结构
$ tree project/
project/
|-- go.mod
|-- main.go
|-- Makefile
|-- path
| `-- to
| `-- package
| `-- test1280.go
`-- VERSION
3 directories, 5 files
2.2.文件内容
go.mod
module gitlab.test1280.com/group/project
go 1.16
main.go
package main
import (
"flag"
"fmt"
_package "gitlab.test1280.com/group/project/path/to/package"
"os"
)
func main() {
var v bool
flag.BoolVar(&v, "v", false, "Show Version")
flag.Parse()
if v {
fmt.Printf("Version : %s\n", _package.Version)
fmt.Printf("Go Version : %s\n", _package.GoVersion)
fmt.Printf("Built : %s\n", _package.Built)
fmt.Printf("Git Commit : %s\n", _package.GitCommit)
fmt.Printf("OS/Arch : %s\n", _package.OSArch)
os.Exit(0)
}
fmt.Println("main run ...")
}
Makefile
# 可执行文件
BIN = project
##########################################################################################
#
# 注入变量区
#
# 软件版本
VERSION = `cat VERSION`
# 语言版本
GOVERSION = `go env GOVERSION`
# 构建时刻
BUILT = `date "+%F %T"`
# 哈希摘要
GITCOMMIT = `git rev-parse HEAD`
# 架构信息
OSARCH = `go env GOOS`/`go env GOARCH`
# 注入变量
LDFLAGS = "\
-X 'gitlab.test1280.com/group/project/path/to/package.Version=${VERSION}' \
-X 'gitlab.test1280.com/group/project/path/to/package.GoVersion=${GOVERSION}' \
-X 'gitlab.test1280.com/group/project/path/to/package.Built=${BUILT}' \
-X 'gitlab.test1280.com/group/project/path/to/package.GitCommit=${GITCOMMIT}' \
-X 'gitlab.test1280.com/group/project/path/to/package.OSArch=${OSARCH}' "
##########################################################################################
project:
go build -ldflags ${LDFLAGS} -o ${BIN}
clean:
@echo "clean ..."
@rm -f ${BIN}
@echo "clean OK"
.PHONY: project clean
test1280.go
package _package
var (
Version string
GoVersion string
Built string
GitCommit string
OSArch string
)
VERSION
1.2.3
2.3.版本控制
project 目录是一个 git repo:
$ git log
commit b93b2333426605484e4d03057fd3491b8b117047
Author: xxx <xxx@xxx.com>
Date: Thu Mar 17 16:19:21 2022 +0800
init repo
2.4.测试运行
通过 make 命令按照 Makefile 规则编译构建:
$ make
go build -ldflags " -X 'gitlab.test1280.com/group/project/path/to/package.Version=`cat VERSION`' -X 'gitlab.test1280.com/group/project/path/to/package.GoVersion=`go env GOVERSION`' -X 'gitlab.test1280.com/group/project/path/to/package.Built=`date "+%F %T"`' -X 'gitlab.test1280.com/group/project/path/to/package.GitCommit=`git rev-parse HEAD`' -X 'gitlab.test1280.com/group/project/path/to/package.OSArch=`go env GOOS`/`go env GOARCH`' " -o project
可执行文件 project 已生成:
$ ll
total 2076
-rw-rw-r-- 1 jiang jiang 50 Mar 17 15:23 go.mod
-rw-rw-r-- 1 jiang jiang 531 Mar 17 16:08 main.go
-rw-rw-r-- 1 jiang jiang 1085 Mar 17 16:00 Makefile
drwxrwxr-x 3 jiang jiang 16 Mar 17 15:34 path
-rwxrwxr-x 1 jiang jiang 2105590 Mar 17 16:21 project
-rw-rw-r-- 1 jiang jiang 5 Mar 17 15:42 VERSION
测试:
$ ./project -v
Version : 1.2.3
Go Version : go1.16.2
Built : 2022-03-17 16:21:05
Git Commit : b93b2333426605484e4d03057fd3491b8b117047
OS/Arch : linux/amd64
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