简介
如果你曾经运行过 docker version,
就会发现它提供了很多信息:
PS C:Userstzh> docker version
Client: Docker Engine - Community
Version: 19.03.4
API version: 1.40
Go version: go1.12.10
Git commit: 9013bf5
Built: Thu Oct 17 23:44:48 2019
OS/Arch: windows/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 19.03.4
API version: 1.40 (minimum version 1.12)
Go version: go1.12.10
Git commit: 9013bf5
Built: Thu Oct 17 23:50:38 2019
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: v1.2.10
GitCommit: b34a5c8af56e510852c35414db4c1f4fa6172339
runc:
Version: 1.0.0-rc8+dev
GitCommit: 3e425f80a8c931f88e6d94a8c831b9d5aa481657
docker-init:
Version: 0.18.0
GitCommit: fec3683
对于编译好的二进制文件而言, 获取版本信息是非常重要的.
尽可能地提供详细信息, 有利于后期的维护和排错.
如何实现
对于版本信息等, 有两种方式,
一种从外部获取, 比如配置文件等,
另一种从源代码中获取, 将配置信息写死在源代码中.
这两种都不太好, 比如编译时间就不太好确定.
最好是能在 go build 时确定这些信息.
幸好, go build 提供了一个选项叫做 -ldflags '[pattern=]arg list'.
-X importpath.name=value
Set the value of the string variable in importpath named name to value.
This is only effective if the variable is declared in the source code either uninitialized
or initialized to a constant string expression. -X will not work if the initializer makes
a function call or refers to other variables.
Note that before Go 1.5 this option took two separate arguments.
这使得我们可以在编译生成二进制文件时, 指定某些变量的值.
比如我们有个文件是 company/buildinfo 包的一部分.
package buildinfo
var BuildTime string
运行 go build -ldflags="-X 'company/buildinfo.BuildTime=$(date)'" 会记录编译时间,
将 BuildTime 的值设置为编译时的时间, 即从 $(date) 中获取的时间.
参考:
Compile packages and dependencies
Command link
Including build information in the executable
实践
新增 pkg/version 包, 用于获取版本信息.
package version
// 这些值应该是从外部传入的
var (
gitTag string = ""
gitCommit string = "$Format:%H$" // sha1 from git, output of $(git rev-parse HEAD)
gitTreeState string = "not a git tree" // state of git tree, either "clean" or "dirty"
buildDate string = "1970-01-01T00:00:00Z" // build date in ISO8601 format, output of $(date -u +'%Y-%m-%dT%H:%M:%SZ')
)
package version
import (
"fmt"
"runtime"
)
// 构建时的版本信息
type VersionInfo struct {
GitTag string `json:"git_tag"`
GitCommit string `json:"git_commit"`
GitTreeState string `json:"git_tree_state"`
BuildDate string `json:"build_date"`
GoVersion string `json:"go_version"`
Compiler string `json:"compiler"`
Platform string `json:"platform"`
}
func (info VersionInfo) String() string {
return info.GitTag
}
func Get() VersionInfo {
return VersionInfo{
GitTag: gitTag,
GitCommit: gitCommit,
GitTreeState: gitTreeState,
BuildDate: buildDate,
GoVersion: runtime.Version(),
Compiler: runtime.Compiler,
Platform: fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
}
}
