feat(server): ability to disable metrics

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://git.rustybever.be/vieter-v/vieter/src/branch/dev)
 
+* Metrics endpoint for Prometheus integration
+
 ## [0.5.0](https://git.rustybever.be/vieter-v/vieter/src/tag/0.5.0)
 
 ### Added

src/server/api_metrics.v

@@ -3,14 +3,17 @@ module server
 import metrics
 import web
 
-['/api/v1/metrics'; get]
+// v1_metrics serves a Prometheus-compatible metrics endpoint.
+['/api/v1/metrics'; get; markused]
 fn (mut app App) v1_metrics() web.Result {
+	if !app.conf.collect_metrics {
+		return app.status(.not_found)
+	}
+
 	mut exporter := metrics.new_prometheus_exporter([0.01, 0.05, 0.1, 0.5, 1, 100])
 	exporter.load(app.collector)
 
 	// TODO stream to connection instead
-	body := exporter.export_to_string() or {
+	body := exporter.export_to_string() or { return app.status(.internal_server_error) }
-		return app.status(.internal_server_error)
-	}
 	return app.body(.ok, 'text/plain', body)
 }

src/server/cli.v

@@ -15,6 +15,7 @@ pub:
 	base_image           string = 'archlinux:base-devel'
 	max_log_age          int    [empty_default]
 	log_removal_schedule string = '0 0'
+	collect_metrics      bool   [empty_default]
 }
 
 // cmd returns the cli submodule that handles starting the server

src/server/server.v

@@ -101,14 +101,20 @@ pub fn server(conf Config) ! {
 		util.exit_with_message(1, 'Failed to initialize database: $err.msg()')
 	}
 
+	collector := if conf.collect_metrics {
+		&metrics.MetricsCollector(metrics.new_default_collector())
+	} else {
+		&metrics.MetricsCollector(metrics.new_null_collector())
+	}
+
 	mut app := &App{
 		logger: logger
 		api_key: conf.api_key
 		conf: conf
 		repo: repo
 		db: db
+		collector: collector
 		job_queue: build.new_job_queue(global_ce, conf.base_image)
-		collector: metrics.new_default_collector()
 	}
 	app.init_job_queue() or {
 		util.exit_with_message(1, 'Failed to inialize job queue: $err.msg()')

src/web/web.v

@@ -148,6 +148,7 @@ pub fn (ctx &Context) is_authenticated() bool {
 	return false
 }
 
+// body sends the given body as an HTTP response.
 pub fn (mut ctx Context) body(status http.Status, content_type string, body string) Result {
 	ctx.status = status
 	ctx.content_type = content_type
@@ -334,11 +335,13 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T, routes map[string]Route) {
 		labels := [
 			['method', app.req.method.str()]!,
 			['path', app.req.url]!,
-			['status', app.status.int().str()]!
+			['status', app.status.int().str()]!,
 		]
 		app.collector.counter_increment(name: 'http_requests_total', labels: labels)
-		app.collector.histogram_record(time.ticks() - app.page_gen_start, name: 'http_requests_time_ms', labels: labels)
+		app.collector.histogram_record(time.ticks() - app.page_gen_start,
-		/* app.collector.histogram_ */
+			name: 'http_requests_time_ms'
+			labels: labels
+		)
 
 		unsafe {
 			free(app)

vieter.toml

@@ -13,3 +13,4 @@ api_update_frequency = 2
 image_rebuild_frequency = 1
 max_concurrent_builds = 3
 max_log_age = 64
+collect_metrics = true