Get version information from embedded build info

Makefile

@@ -1,21 +1,16 @@
 MAKEFLAGS += --warn-undefined-variables
 MAKEFLAGS += --no-builtin-rules
 
-TAG ?= $(shell git fetch --tags && git describe --tags --abbrev=0 | sed 's/v//')
-COMMIT ?= $(shell git rev-parse --short HEAD)
-CLEAN ?= $(shell git diff --quiet --exit-code || echo '-SNAPSHOT')
-VERSION = $(TAG)$(CLEAN)-$(COMMIT)
-
 .PHONY: all
 all: vet test build
 
 .PHONY: build
 build:
-	go build -ldflags="-X 'main.version=$(VERSION)'" ./cmd/provider 
+	go build ./cmd/provider 
 
 .PHONY: docker
 docker: clean
-	docker build . --force-rm -f Dockerfile -t index-provider:$(VERSION)
+	docker build . --force-rm -f Dockerfile -t index-provider:$(shell git rev-parse --short HEAD)
 
 .PHONY: install
 install:

cmd/provider/provider.go

@@ -7,11 +7,10 @@ import (
 	"os/signal"
 	"syscall"
 
+	"github.com/ipni/index-provider"
 	"github.com/urfave/cli/v2"
 )
 
-var version = "unknown"
-
 func main() {
 	os.Exit(run())
 }
@@ -36,6 +35,17 @@ func run() int {
 		signal.Stop(interrupt)
 	}()
 
+	var rev string
+	if provider.Modified {
+		rev = "SNAPSHOT"
+	} else {
+		rev = provider.Revision
+		if len(rev) > 7 {
+			rev = rev[:7]
+		}
+	}
+	version := provider.Release + "-" + rev
+
 	app := &cli.App{
 		Name:    "provider",
 		Usage:   "Indexer Reference Provider Implementation",

version.go

@@ -0,0 +1,52 @@
+package provider
+
+import (
+	_ "embed"
+	"encoding/json"
+	"runtime/debug"
+)
+
+var (
+	// Release is the release version tag value, e.g. "v1.2.3"
+	Release string
+	// Revision is the git commit hash.
+	Revision string
+	// Version is the full version string: Release-Revision.
+	Version string
+	// Modified indicates if the source tree had local modifications.
+	Modified bool
+)
+
+//go:embed version.json
+var versionJSON []byte
+
+func init() {
+	// Read version from embedded JSON file.
+	var verMap map[string]string
+	json.Unmarshal(versionJSON, &verMap)
+	Release = verMap["version"]
+
+	// If running from a module, try to get the build info.
+	bi, ok := debug.ReadBuildInfo()
+	if !ok {
+		return
+	}
+
+	var found int
+
+	// Append the revision to the version.
+	for i := range bi.Settings {
+		switch bi.Settings[i].Key {
+		case "vcs.revision":
+			Revision = bi.Settings[i].Value
+			Version = Release + "-" + Revision
+			found++
+		case "vcs.modified":
+			Modified = bi.Settings[i].Value == "true"
+			found++
+		}
+		if found == 2 {
+			break
+		}
+	}
+}