feat(server): add metric collection

src/server/api_metrics.v

@@ -0,0 +1,16 @@
+module server
+
+import metrics
+import web
+
+['/api/v1/metrics'; get]
+fn (mut app App) v1_metrics() web.Result {
+	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 {
+		return app.status(.internal_server_error)
+	}
+	return app.body(.ok, 'text/plain', body)
+}

src/server/server.v

@@ -8,6 +8,7 @@ import util
 import db
 import build { BuildJobQueue }
 import cron.expression
+import metrics
 
 const (
 	log_file_name = 'vieter.log'
@@ -107,6 +108,7 @@ pub fn server(conf Config) ! {
 		repo: repo
 		db: db
 		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/v.mod

@@ -2,6 +2,7 @@ Module {
     dependencies: [
         'https://git.rustybever.be/vieter-v/conf',
         'https://git.rustybever.be/vieter-v/docker',
-        'https://git.rustybever.be/vieter-v/aur'
+        'https://git.rustybever.be/vieter-v/aur',
+        'https://git.rustybever.be/vieter-v/metrics'
     ]
 }

src/web/web.v

@@ -11,6 +11,7 @@ import net.urllib
 import time
 import json
 import log
+import metrics
 
 // The Context struct represents the Context which hold the HTTP request and response.
 // It has fields for the query, form, files.
@@ -27,6 +28,8 @@ pub mut:
 	conn &net.TcpConn = unsafe { nil }
 	// Gives access to a shared logger object
 	logger shared log.Log
+	// Used to collect metrics on the web server
+	collector &metrics.MetricsCollector
 	// time.ticks() from start of web connection handle.
 	// You can use it to determine how much time is spent on your request.
 	page_gen_start i64
@@ -145,6 +148,14 @@ pub fn (ctx &Context) is_authenticated() bool {
 	return false
 }
 
+pub fn (mut ctx Context) body(status http.Status, content_type string, body string) Result {
+	ctx.status = status
+	ctx.content_type = content_type
+	ctx.send_response(body)
+
+	return Result{}
+}
+
 // json<T> HTTP_OK with json_s as payload with content-type `application/json`
 pub fn (mut ctx Context) json<T>(status http.Status, j T) Result {
 	ctx.status = status
@@ -319,6 +330,16 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T, routes map[string]Route) {
 			app.logger.flush()
 		}
 
+		// Record how long request took to process
+		labels := [
+			['method', app.req.method.str()]!,
+			['path', app.req.url]!,
+			['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_ */
+
 		unsafe {
 			free(app)
 		}
@@ -384,6 +405,7 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T, routes map[string]Route) {
 		static_mime_types: app.static_mime_types
 		reader: reader
 		logger: app.logger
+		collector: app.collector
 		api_key: app.api_key
 	}