Add Prometheus statistics and an example to showcase them using Grafana

api/agent/agent.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net/http"
 	"sort"
 	"sync"
 	"time"
@@ -17,6 +18,7 @@ import (
 	"github.com/fnproject/fn/api/id"
 	"github.com/fnproject/fn/api/models"
 	"github.com/opentracing/opentracing-go"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/sirupsen/logrus"
 )
 
@@ -105,6 +107,9 @@ type Agent interface {
 	// Stats should be burned at the stake. adding so as to not ruffle feathers.
 	// TODO this should be derived from our metrics
 	Stats() Stats
+
+	// Return the http.Handler used to handle Prometheus metric requests
+	PromHandler() http.Handler
 }
 
 type agent struct {
@@ -131,6 +136,9 @@ type agent struct {
 	shutdown chan struct{}
 
 	stats // TODO kill me
+
+	// Prometheus HTTP handler
+	promHandler http.Handler
 }
 
 func New(ds models.Datastore, mq models.MessageQueue) Agent {
@@ -138,13 +146,14 @@ func New(ds models.Datastore, mq models.MessageQueue) Agent {
 	driver := docker.NewDocker(drivers.Config{})
 
 	a := &agent{
-		ds:       ds,
-		mq:       mq,
-		driver:   driver,
-		hot:      make(map[string]chan slot),
-		cond:     sync.NewCond(new(sync.Mutex)),
-		ramTotal: getAvailableMemory(),
-		shutdown: make(chan struct{}),
+		ds:          ds,
+		mq:          mq,
+		driver:      driver,
+		hot:         make(map[string]chan slot),
+		cond:        sync.NewCond(new(sync.Mutex)),
+		ramTotal:    getAvailableMemory(),
+		shutdown:    make(chan struct{}),
+		promHandler: promhttp.Handler(),
 	}
 
 	go a.asyncDequeue() // safe shutdown can nanny this fine

api/agent/prometheus_metrics.go

@@ -0,0 +1,9 @@
+package agent
+
+import (
+	"net/http"
+)
+
+func (a *agent) PromHandler() http.Handler {
+	return a.promHandler
+}

api/agent/stats.go

@@ -1,6 +1,9 @@
 package agent
 
-import "sync"
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"sync"
+)
 
 // TODO this should expose:
 // * hot containers active
@@ -44,6 +47,44 @@ type FunctionStats struct {
 	Failed   uint64
 }
 
+var (
+	fnQueued = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "fn_api_queued",
+			Help: "Queued requests by path",
+		},
+		[](string){"path"},
+	)
+	fnRunning = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "fn_api_running",
+			Help: "Running requests by path",
+		},
+		[](string){"path"},
+	)
+	fnCompleted = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "fn_api_completed",
+			Help: "Completed requests by path",
+		},
+		[](string){"path"},
+	)
+	fnFailed = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "fn_api_failed",
+			Help: "Failed requests by path",
+		},
+		[](string){"path"},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(fnQueued)
+	prometheus.MustRegister(fnRunning)
+	prometheus.MustRegister(fnFailed)
+	prometheus.MustRegister(fnCompleted)
+}
+
 func (s *stats) getStatsForFunction(path string) *functionStats {
 	if s.functionStatsMap == nil {
 		s.functionStatsMap = make(map[string]*functionStats)
@@ -59,52 +100,78 @@ func (s *stats) getStatsForFunction(path string) *functionStats {
 
 func (s *stats) Enqueue(path string) {
 	s.mu.Lock()
+
 	s.queue++
 	s.getStatsForFunction(path).queue++
+	fnQueued.WithLabelValues(path).Inc()
+
 	s.mu.Unlock()
 }
 
 // Call when a function has been queued but cannot be started because of an error
 func (s *stats) Dequeue(path string) {
 	s.mu.Lock()
+
 	s.queue--
 	s.getStatsForFunction(path).queue--
+	fnQueued.WithLabelValues(path).Dec()
+
 	s.mu.Unlock()
 }
 
 func (s *stats) DequeueAndStart(path string) {
 	s.mu.Lock()
+
 	s.queue--
 	s.getStatsForFunction(path).queue--
+	fnQueued.WithLabelValues(path).Dec()
+
 	s.running++
 	s.getStatsForFunction(path).running++
+	fnRunning.WithLabelValues(path).Inc()
+
 	s.mu.Unlock()
 }
 
 func (s *stats) Complete(path string) {
 	s.mu.Lock()
+
 	s.running--
 	s.getStatsForFunction(path).running--
+	fnRunning.WithLabelValues(path).Dec()
+
 	s.complete++
 	s.getStatsForFunction(path).complete++
+	fnCompleted.WithLabelValues(path).Inc()
+
 	s.mu.Unlock()
 }
 
 func (s *stats) Failed(path string) {
 	s.mu.Lock()
+
 	s.running--
 	s.getStatsForFunction(path).running--
+	fnRunning.WithLabelValues(path).Dec()
+
 	s.failed++
 	s.getStatsForFunction(path).failed++
+	fnFailed.WithLabelValues(path).Inc()
+
 	s.mu.Unlock()
 }
 
 func (s *stats) DequeueAndFail(path string) {
 	s.mu.Lock()
+
 	s.queue--
 	s.getStatsForFunction(path).queue--
+	fnQueued.WithLabelValues(path).Dec()
+
 	s.failed++
 	s.getStatsForFunction(path).failed++
+	fnFailed.WithLabelValues(path).Inc()
+
 	s.mu.Unlock()
 }
 

api/server/prometheus_metrics.go

@@ -0,0 +1,9 @@
+package server
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+func (s *Server) handlePrometheusMetrics(c *gin.Context) {
+	s.Agent.PromHandler().ServeHTTP(c.Writer, c.Request)
+}

api/server/server.go

@@ -280,6 +280,7 @@ func (s *Server) bindHandlers(ctx context.Context) {
 	engine.GET("/", handlePing)
 	engine.GET("/version", handleVersion)
 	engine.GET("/stats", s.handleStats)
+	engine.GET("/metrics", s.handlePrometheusMetrics)
 
 	{
 		v1 := engine.Group("/v1")

examples/grafana/README.md

@@ -0,0 +1,100 @@
+# Display runtime metrics using Prometheus and Grafana
+
+The Fn server exports metrics using [Prometheus](https://prometheus.io/). This allows [Grafana](https://grafana.com/) to be used to display these metrics graphically. 
+
+-- screenshot
+
+## Start a fn server and deploy some functions
+
+This example requires a Fn server to be running and that you have deployed one or more functions. 
+See the [front page](/README.md) or any of the other examples for instructions. 
+
+The steps below assume that the Fn server is running at `localhost:8080`.
+
+## Examine the endpoint used to export metrics to Prometheus
+
+The Fn server exports metrics to Prometheus using the API endpoint `/metrics`. 
+
+Try pointing your browser at [http://localhost:8080/metrics](http://localhost:8080/metrics).
+This will display the metrics in prometheus format.
+
+## Start Prometheus
+
+Open a terminal window and navigate to the directory containing this example.
+
+Examine the provised Prometheus configuration file:
+
+```
+cat prometheus.yml
+```
+
+This gives
+
+``` yml
+global:
+  scrape_interval:     15s # By default, scrape targets every 15 seconds.
+
+  # Attach these labels to any time series or alerts when communicating with
+  # external systems (federation, remote storage, Alertmanager).
+  external_labels:
+    monitor: 'fn-monitor'
+
+# A scrape configuration containing exactly one endpoint to scrape:
+# Here it's the Fn server
+scrape_configs:
+  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
+  - job_name: 'functions'
+
+    # Override the global default and scrape targets from this job every 5 seconds.
+    scrape_interval: 5s
+
+    static_configs:
+      # Specify all the fn servers from which metrics will be scraped
+      - targets: ['localhost:8080'] # Uses /metrics by default
+```
+Note the last line. This specifies the host and port of the Fn server from which metrics will be obtained. 
+If you are running a cluster of Fn servers then you can specify them all here.
+
+Now start Prometheus, specifying this config file:
+```
+docker run --name=prometheus -d -p 9090:9090 \
+  --mount type=bind,source=`pwd`/prometheus.yml,target=/etc/prometheus/prometheus.yml \
+  --add-host="localhost:`route | grep default | awk '{print $2}'`" prom/prometheus
+```
+Note: The parameter `` --add-host="localhost:`route | grep default | awk '{print $2}'`" `` means that Prometheus can use localhost to refer to the host. (The expression `` `route | grep default | awk '{print $2}'` ``  returns the IP of the host).
+
+Open a browser on Prometheus's graph tool at [http://localhost:9090/graph](http://localhost:9090/graph). If you wish you can use this to view metrics and display metrics from the fn server: see the [Prometheus](https://prometheus.io/) documentation for instructions. Alternatively continue with the next step to view a ready-made set of graphs in Grafana.
+
+## Start Grafana and load the example dashboard
+
+[Grafana](https://grafana.com/) provides powerful and flexible facilities to create graphs of any metric available to Prometheus. This example provides a ready-made dashboard that displays the numbers of functions that are queued, running, completed and failed. 
+
+Open a terminal window and navigate to the directory containing this example.
+
+Start Grafana on port 3000:
+```
+docker run --name=grafana -d -p 3000:3000 \
+  --add-host="localhost:`route | grep default | awk '{print $2}'`" grafana/grafana
+```
+
+Open a browser on Grafana at [http://localhost:3000](http://localhost:3000).
+
+Login using the default user `admin` and default password `admin`.
+
+Create a datasource to obtain metrics from Promethesus:
+* Click on **Add data source**. In the form that opens:
+* Set **Name** to `PromDS` (or whatever name you choose)
+* Set **Type** to `Prometheus`
+* Set **URL** to `http://localhost:9090` 
+* Set **Access** to `proxy`
+* Click **Add** and then **Save and test**
+
+Import the example dashboard that displays metrics from the Fn server:
+* Click on the main menu at the top left and choose **Dashboards** and then **Home**
+* Click on **Home** at the top and then **Import dashboard**
+* In the dialog that opens, click **Upload .json file** and specify `fn_grafana_dashboard.json` in this example's directory.
+* Specify the Prometheus data source that you just created
+* Click **Import**
+
+You should then see the dashboard shown above. Now execute some functions and see the graphs update.
+

examples/grafana/prometheus.yml

@@ -0,0 +1,20 @@
+global:
+  scrape_interval:     15s # By default, scrape targets every 15 seconds.
+
+  # Attach these labels to any time series or alerts when communicating with
+  # external systems (federation, remote storage, Alertmanager).
+  external_labels:
+    monitor: 'fn-monitor'
+
+# A scrape configuration containing exactly one endpoint to scrape:
+# Here it's the Fn server
+scrape_configs:
+  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
+  - job_name: 'functions'
+
+    # Override the global default and scrape targets from this job every 5 seconds.
+    scrape_interval: 5s
+
+    static_configs:
+      # Specify all the fn servers from which metrics will be scraped
+      - targets: ['localhost:8080'] # Uses /metrics by default

glide.yaml

@@ -67,6 +67,7 @@ import:
   version: 19f72df4d05d31cbe1c56bfc8045c96babff6c7e
 - package: github.com/prometheus/common
   version: 2f17f4a9d485bf34b4bfaccc273805040e4f86c8
+- package: github.com/prometheus/client_golang
 testImport:
 - package: github.com/patrickmn/go-cache
   branch: master