From 26c2f78657ae965a1070375df174e874f36cf13f Mon Sep 17 00:00:00 2001
From: Adam Snyder <asnyder@ea.com>
Date: Sun, 1 Aug 2021 22:24:19 -0700
Subject: [PATCH] Add build version flag

---
 .github/workflows/ci.yaml |  2 ++
 Dockerfile                |  3 ++-
 README.md                 | 11 +++++++++--
 main.go                   | 16 +++++++++++++---
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 00483e3..99d032d 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -54,6 +54,7 @@ jobs:
         with:
           context: .
           push: false
+          build-args: BUILD_VERSION=${{ steps.meta.outputs.version }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
 
@@ -63,6 +64,7 @@ jobs:
         with:
           context: .
           push: true
+          build-args: BUILD_VERSION=${{ steps.meta.outputs.version }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
 
diff --git a/Dockerfile b/Dockerfile
index 968bf84..d3b07ff 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,7 +4,8 @@ COPY go.mod go.sum ./
 RUN go mod download
 COPY internal internal
 COPY *.go .
-RUN GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -ldflags="-w -s" -o /bin/a2s-exporter .
+ARG BUILD_VERSION=development
+RUN GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -ldflags="-w -s -X 'main.buildVersion=$BUILD_VERSION'" -o /bin/a2s-exporter .
 
 FROM scratch
 COPY --from=builder /bin/a2s-exporter /bin/a2s-exporter
diff --git a/README.md b/README.md
index 3f2a297..d8dc4ec 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,13 @@ Flag | Variable | Default | Help
 --namespace | A2S_EXPORTER_NAMESPACE | a2s | Namespace prefix for all exported a2s metrics.
 --a2s-only-metrics | A2S_EXPORTER_A2S_ONLY_METRICS | false | If true, excludes Go runtime and promhttp metrics.
 
+#### Special
+
+Flag | Help
+--- | ---
+-h | Show help.
+--version | Show build version.
+
 ## Exported Metrics
 
 Metrics names are prefixed with a namespace (default `a2s_`).
@@ -50,7 +57,7 @@ player_duration | Time (in seconds) player has been connected to the server. | s
 player_score | Player's score (usually \"frags\" or \"kills\"). | server_name player_name player_index
 player_the_ship_deaths | Player's deaths in a The Ship server. | server_name player_name player_index
 player_the_ship_money | Player's money in a The Ship server. | server_name player_name player_index
-player_up | Was the last player info query successful. | 
+player_up | Was the last player info query successful. |
 server_bots | Number of bots on the server. | server_name
 server_info | Non-numerical server info, including server_steam_id and version. The value is 1, and info is in the labels. | server_name map folder game server_type server_os version server_id keywords server_game_id server_steam_id the_ship_mode source_tv_name
 server_max_players | Maximum number of players the server reports it can hold. | server_name
@@ -60,7 +67,7 @@ server_protocol | Protocol version used by the server. | server_name
 server_source_tv_port | Spectator port number for SourceTV. | server_name
 server_the_ship_duration | Time (in seconds) before a player is arrested while being witnessed in a The Ship server. | server_name
 server_the_ship_witnesses | The number of witnesses necessary to have a player arrested in a The Ship server. | server_name
-server_up | Was the last server info query successful. | 
+server_up | Was the last server info query successful. |
 server_vac | Specifies whether the server uses VAC (0 for unsecured, 1 for secured). | server_name
 server_visibility | Indicates whether the server requires a password (0 for public, 1 for private). | server_name
 
diff --git a/main.go b/main.go
index e924e07..3b2b47a 100644
--- a/main.go
+++ b/main.go
@@ -14,6 +14,9 @@ import (
 	"github.com/armsnyder/a2s-exporter/internal/collector"
 )
 
+// buildVersion variable is set at build time.
+var buildVersion = "development"
+
 func main() {
 	// Flags.
 	address := flag.String("address", envOrDefault("A2S_EXPORTER_QUERY_ADDRESS", ""), "Address of the A2S query server as host:port (This is a separate port from the main server port).")
@@ -22,22 +25,27 @@ func main() {
 	namespace := flag.String("namespace", envOrDefault("A2S_EXPORTER_NAMESPACE", "a2s"), "Namespace prefix for all exported a2s metrics.")
 	a2sOnlyMetrics := flag.Bool("a2s-only-metrics", envOrDefaultBool("A2S_EXPORTER_A2S_ONLY_METRICS", false), "If true, skips exporting Go runtime metrics.")
 	help := flag.Bool("h", false, "Show help.")
+	version := flag.Bool("version", false, "Show build version.")
 
 	flag.Parse()
 
-	defer os.Exit(1)
+	// Show version.
+	if *version || flag.Arg(0) == "version" {
+		fmt.Println(buildVersion)
+		os.Exit(0)
+	}
 
 	// Show help.
 	if *help || flag.NArg() > 0 {
 		flag.Usage()
-		return
+		os.Exit(1)
 	}
 
 	// Check required arguments.
 	if *address == "" {
 		fmt.Println("address argument is required")
 		flag.Usage()
-		return
+		os.Exit(1)
 	}
 
 	// Set up prometheus metrics registry.
@@ -62,6 +70,8 @@ func main() {
 	// Run http server.
 	fmt.Printf("Serving metrics at http://127.0.0.1:%d%s\n", *port, *path)
 	fmt.Println(http.ListenAndServe(fmt.Sprintf(":%d", *port), nil))
+
+	os.Exit(1)
 }
 
 func envOrDefault(key, def string) string {