buildinfo: compile time variables

These expose entrypoints for -ldflag injections at compile time,
containing metadata about build env + SCM

buildinfo/build.go

@@ -0,0 +1,46 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+package build
+
+import (
+	"strings"
+
+	"golang.org/x/exp/slices"
+)
+
+var (
+	// Git tag of this binary
+	Version = "v0.0.0+devel"
+	// Git hash of this binary
+	CommitHash = "0000000000000000000000000000000000000000"
+	// Enabled features of this binary
+	Features = ""
+
+	knownFeatures = map[string]bool{}
+)
+
+// Get the short Git hash
+func ShortHash() string {
+	return CommitHash[:7]
+}
+
+// Get list of features enabled
+func FeaturesList() []string {
+	out := []string{}
+	active := strings.Split(Features, ",")
+
+	for feature, _ := range knownFeatures {
+		sy := "-"
+		if slices.Contains(active, feature) {
+			sy = "+"
+		}
+		out = append(out, sy+feature)
+	}
+	slices.Sort(out)
+
+	return out
+}