Build and report the BuildDate

Makefile

@@ -1,11 +1,13 @@
-SOURCEDIR=.
-SOURCES := $(shell find $(SOURCEDIR) -name '*.go')
-
 BINARY = gojekyll
 PACKAGE = github.com/osteele/gojekyll
+
+SOURCEDIR = .
+SOURCES := $(shell find $(SOURCEDIR) -name '*.go')
+
 COMMIT_HASH = `git rev-parse --short HEAD 2>/dev/null`
+BUILD_DATE = `date +%FT%T%z`
 
-LDFLAGS=-ldflags "-X ${PACKAGE}.commands.Version=${COMMIT_HASH}"
+LDFLAGS=-ldflags "-X ${PACKAGE}/cmd.Version=${COMMIT_HASH} -X ${PACKAGE}/cmd.BuildDate=${BUILD_DATE} "
 
 .DEFAULT_GOAL: build
 .PHONY: build clean deps setup install lint test help
@@ -16,7 +18,7 @@ $(BINARY): $(SOURCES)
 build: $(BINARY) ## compile the package
 
 clean: ## remove binary files
-	rm -fI ${BINARY}
+	rm -f ${BINARY}
 
 imports: ## list imports
 	go list -f '{{join .Imports "\n"}}' ./... | grep -v `go list -f '{{.ImportPath}}'` | grep '\.' | sort | uniq

cmd/commands.go

@@ -164,6 +164,10 @@ func variablesCommand(site *site.Site) (err error) {
 }
 
 func versionCommand() error {
-	fmt.Printf("gojekyll %s\n", Version)
+	var d string
+	if !BuildTime.IsZero() {
+		d = BuildTime.Format(" (Build time: 2006-01-02T15:04)")
+	}
+	fmt.Printf("gojekyll version %s%s\n", Version, d)
 	return nil
 }

cmd/version.go

@@ -1,12 +1,28 @@
 package cmd
 
-// Version is the build version.
-//
-// Make initializes this to the git commit hash.
-var Version string
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+// Make initializes Version to the git commit hash, and BuildDate.
+var (
+	Version   string
+	BuildDate string
+	BuildTime time.Time
+)
 
 func init() {
 	if Version == "" {
 		Version = "develop"
 	}
+	if BuildDate != "" {
+		bd, err := time.Parse("2006-01-02T15:04:05-0700", BuildDate)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "invalid BuildDate", BuildDate) // nolint: gas
+		} else {
+			BuildTime = bd.In(time.UTC)
+		}
+	}
 }