Add --version flag (#145)

Makefile

@@ -25,7 +25,7 @@ all: fmt lint vet build
 .PHONY: build
 build: $(BIN) ; $(info $(M) building executable…) @ ## Build program binary
 	$Q CGO_ENABLED=0 $(GO) build \
-		-ldflags "-X main.gitVersion=$$(git describe --tags) -X \"main.buildTime=$$(date -u '+%Y-%m-%d %H:%M:%S %Z')\"" \
+		-ldflags "-X main.gitVersion=$$(git describe --tags) -X $(MODULE)/cmd.gitVersion=$$(git describe --tags) -X \"main.buildTime=$$(date -u '+%Y-%m-%d %H:%M:%S %Z')\" -X \"$(MODULE)/cmd.buildTime=$$(date -u '+%Y-%m-%d %H:%M:%S %Z')\"" \
 		-tags release \
 		-o $(BIN)/$(notdir $(basename $(MODULE)))$(binext)
 # Tools

cmd/root.go

@@ -11,11 +11,16 @@ import (
 )
 
 var cfgFile string
+var (
+	gitVersion string
+	buildTime string
+)
 
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
 	Use:   "chia-exporter",
 	Short: "Prometheus metric exporter for Chia Blockchain",
+	Version: fmt.Sprintf("%s (%s)", gitVersion, buildTime),
 }
 
 // Execute adds all child commands to the root command and sets flags appropriately.