Merge pull request 'Add Prometheus metrics endpoint' (#325) from Chewing_Bever/vieter:metrics into dev

Reviewed-on: #325

.woodpecker/man.yml

@@ -8,15 +8,21 @@ branches:
 depends_on:
   - build
 
-skip_clone: true
-
 pipeline:
-  generate:
+  install-modules:
     image: *vlang_image
     pull: true
     commands:
-      - curl -o vieter -L "https://s3.rustybever.be/vieter/commits/$CI_COMMIT_SHA/vieter-linux-amd64"
-      - chmod +x vieter
+      - export VMODULES=$PWD/.vmodules
+      - 'cd src && v install'
+
+  generate:
+    image: *vlang_image
+    commands:
+      # - curl -o vieter -L "https://s3.rustybever.be/vieter/commits/$CI_COMMIT_SHA/vieter-linux-amd64"
+      # - chmod +x vieter
+      - export VMODULES=$PWD/.vmodules
+      - make
       - ./vieter man man
       - cd man
 

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

@@ -0,0 +1,19 @@
+module server
+
+import metrics
+import web
+
+// 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 { 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

@@ -8,6 +8,7 @@ import util
 import db
 import build { BuildJobQueue }
 import cron.expression
+import metrics
 
 const (
 	log_file_name = 'vieter.log'
@@ -100,12 +101,19 @@ 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)
 	}
 	app.init_job_queue() or {

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 +148,15 @@ 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
+	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 +331,18 @@ 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
+		)
+
 		unsafe {
 			free(app)
 		}
@@ -384,6 +408,7 @@ 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
 	}
 

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