Application auto build versioning

Question

Is it possible to increment a minor version number automatically each time a Go app is compiled?

I would like to set a version number inside my program, with an auto

Answer 1

Use ldflags to set variables in main package:

With file main.go:

package main

import "fmt"

var (
    version string
    build   string
)

func main() {
    fmt.Println("version=", version)
    fmt.Println("build=", build)
}

Then run:

go run \
  -ldflags "-X main.version=1.0.0 -X main.build=12082019" \ 
  main.go

Build:

go build -o mybinary \
  -ldflags "-X main.version=1.0.0 -X 'main.build=$(date)'" \ 
  main.go

---

Use ldflags to set variable in a non-main package:

With file config.go:

package config

import "fmt"

var (
    Version string
)

func LogVersion() {
    fmt.Println("version=", Version)
}

You will also need file main.go:

package main

import (
    "fmt"
    "github.com/user/repo/config"
}

func main() {
    config.LogVersion()
}

Build your binary first:

go build -o mybinary main.go 

Find the full path of variable name you want to set:

go tool nm  | grep Version

Run and build the binary again but with the ldflags:

go run \
  -ldflags "-X github.com/user/repo/config.Version=1.0.0" \
  main.go --version       


go build -o mybinary \
  -ldflags "-X github.com/user/repo/config.Version=1.0.0" \
  main.go     

---

Inspired by https://github.com/golang/go/wiki/GcToolchainTricks#including-build-information-in-the-executable

---

Also if you are using goreleaser then read this https://goreleaser.com/environment/#using-the-mainversion :

Default wise GoReleaser sets three ldflags:

main.version: Current Git tag
main.commit: Current git commit SHA
main.date: Date according RFC3339

---

If you want to see this in action: https://github.com/hoto/fuzzy-repo-finder/blob/master/pkg/config/config.go