Generate semantic build versions from Git tags

makefile

@@ -5,7 +5,8 @@ OS ?= $(shell uname)
 ARCH ?= $(shell uname -m)
 
 # Retrieve version from git history
-VERSION ?= $(shell git describe --tags 2>/dev/null || echo unknown)
+VERSION_SCRIPT := scripts/version
+VERSION := $(shell $(VERSION_SCRIPT))
 
 # Path to lint tool
 GOLINTER ?= golangci-lint

scripts/version

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+# Use the nearest vMAJOR.MINOR.PATCH tag; fall back to "unknown" outside Git history.
+describe=$(git describe --tags --long --match 'v[0-9]*.[0-9]*.[0-9]*' 2>/dev/null) || {
+    echo unknown
+    exit 0
+}
+
+tag=$(printf '%s\n' "$describe" | sed 's/-[0-9][0-9]*-g[0-9a-f][0-9a-f]*$//')
+suffix=$(printf '%s\n' "$describe" | sed "s/^$tag-//")
+distance=${suffix%%-g*}
+commit=${suffix#*-g}
+
+# Exact tags keep their version. Later commits use the next patch plus distance and commit ID.
+if [ "$distance" -eq 0 ]; then
+    echo "$tag"
+    exit 0
+fi
+
+version=${tag#v}
+IFS=.
+set -- $version
+printf 'v%s.%s.%s-%s+%s\n' "$1" "$2" "$(( $3 + 1 ))" "$distance" "$commit"