Log version string on startup

.drone.build.yml

@@ -8,9 +8,9 @@ steps:
 - name: build
   image: golang:1.15-alpine3.12
   commands:
-  - CGO_ENABLED=0 go build .
-  - apk --no-cache add binutils
-  - strip -s postfix-ratelimiter
+  - apk --no-cache add make git
+  - git fetch --tags
+  - CGO_ENABLED=0 make
 
 - name: docker
   image: plugins/docker:19

.drone.yml

@@ -4,7 +4,7 @@ kind: pipeline
 name: build-arm64
 platform: {arch: arm64, os: linux, variant: v8}
 steps:
-- commands: [CGO_ENABLED=0 go build ., apk --no-cache add binutils, strip -s postfix-ratelimiter]
+- commands: [apk --no-cache add make git, git fetch --tags, CGO_ENABLED=0 make]
   image: golang:1.15-alpine3.12
   name: build
 - image: plugins/docker:19
@@ -23,7 +23,7 @@ kind: pipeline
 name: build-arm
 platform: {arch: arm, os: linux, variant: v7}
 steps:
-- commands: [CGO_ENABLED=0 go build ., apk --no-cache add binutils, strip -s postfix-ratelimiter]
+- commands: [apk --no-cache add make git, git fetch --tags, CGO_ENABLED=0 make]
   image: golang:1.15-alpine3.12
   name: build
 - image: plugins/docker:19
@@ -42,7 +42,7 @@ kind: pipeline
 name: build-amd64
 platform: {arch: amd64, os: linux}
 steps:
-- commands: [CGO_ENABLED=0 go build ., apk --no-cache add binutils, strip -s postfix-ratelimiter]
+- commands: [apk --no-cache add make git, git fetch --tags, CGO_ENABLED=0 make]
   image: golang:1.15-alpine3.12
   name: build
 - image: plugins/docker:19

Makefile

@@ -0,0 +1,11 @@
+all: postfix-ratelimiter
+
+VERSION = $(shell git describe --tags)
+
+GO = go
+
+postfix-ratelimiter:
+	$(GO) build -ldflags "-s -X main.version=$(VERSION)" .
+
+clean:
+	rm -f postfix-ratelimiter

main.go

@@ -16,6 +16,8 @@ import (
 	"github.com/rkojedzinszky/postfix-sasl-exporter/server"
 )
 
+var version = "devel"
+
 func main() {
 	defaultrate := flag.Float64("default-rate", 1, "Default rate for policing (recipient/seconds)")
 	defaultburst := flag.Float64("default-burst", 60, "Default burst for policing")
@@ -61,6 +63,8 @@ func main() {
 		users:        make(map[string]*tbf),
 	}
 
+	log.Printf("postfix-ratelimiter version %s starting", version)
+
 	ctx, cancel := context.WithCancel(context.Background())
 	wg := &sync.WaitGroup{}