Version info for app

version.txt

Here's a simple example, hopefully it would clarify and help how to do it easily:

Create a directory for your application:

$ mkdir app && cd app

Create a sub directory config:

$ mkdir config 

Add the following file. it should be under app/config/vars.go:

package config

var Version string 

var BuildTime string 
//todo: can add as many as build vars 

In the root app/, add main package main.go:

package main

import (
    "fmt"
    "app/config"
)

func main() {
    fmt.Println("build.Version:\t", Version)
    fmt.Println("build.Time:\t", build.BuildTime)
}

Now it is time to build:

go build -ldflags "-X 'app/config.Version=0.0.1' -X 'app/config.BuildTime=$(date)'" 

Once it's built, you can run now the app:

$ ./app 
Version:     0.0.1
build.Time:  Sat Jul  4 19:49:19 UTC 2020

Finally, you may need sometimes to explore what does specific app you didn't code yourself provide in ldflags, you can do this by using nm that comes with go tool to list all ldflags.

Just build the app then use go tool nm to list all linker flags.

$ go build -o app 
$ go tool nm ./app