set variables at build time #go

build.sh #snippet

#!/usr/bin/env bash

BUILD_TIME="$(date --iso-8601=seconds)"
COMMIT_SHA="$(git rev-parse HEAD 2>/dev/null && true)"

# or
# git rev-parse --short=8 HEAD 2>/dev/null && true
COMMIT_SHORT_SHA="${COMMIT_SHA:0:8}"

BRANCH_NAME=$(git rev-parse --abbrev-ref HEAD && true)

COMMIT_TAG="$(git tag --points-at $COMMIT_SHA && true)"

BUILD_HOSTNAME=$(hostname)

BUILD_USERNAME=$USER

# Reference the build-time variables as <package>.<Varname>
go build -o main \
  -ldflags="-X main.Version=$COMMIT_TAG \
    -X main.BuildCommit=$COMMIT_SHA \
    -X main.BuildShortCommit=$COMMIT_SHORT_SHA \
    -X main.BranchName=$BRANCH_NAME \
    -X main.BuildTime=$BUILD_TIME \
    -X main.BuildHostname=$BUILD_HOSTNAME \
    -X main.BuildUsername=$BUILD_USERNAME" \
  .

main.go

package main

import (
	"fmt"
	"strings"

	"log"
)

// Declare public variables to be set at build-time
var (
	BuildTime        string
	BuildCommit      string
	BuildShortCommit string
	BuildBranch      string
	BuildHostname    string
	BuildUsername    string
	Version          string
)

// GetBuildInfo returns a list of strings for either printing or logging
func GetBuildInfo() []string {
	longLine := strings.Replace(fmt.Sprintf("+%61s+", ""), " ", "-", 61)
	return []string{
		longLine,
		fmt.Sprintf("| Version:          %-41s |", Version),
		fmt.Sprintf("| BuildTime:        %-41s |", BuildTime),
		fmt.Sprintf("| BuildCommit:      %-41s |", BuildCommit),
		fmt.Sprintf("| BuildShortCommit: %-41s |", BuildShortCommit),
		fmt.Sprintf("| BuildBranch:      %-41s |", BuildBranch),
		fmt.Sprintf("| BuildHostname:    %-41s |", BuildHostname),
		fmt.Sprintf("| BuildUsername:    %-41s |", BuildUsername),
		fmt.Sprintf(longLine),
	}
}

func main() {
	for _, line := range GetBuildInfo() {
		log.Println(line)
	}
}