Add a small prometheus exporter

db.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"log"
 
-	gobmarsh "gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
+	"gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
 	bolt "go.etcd.io/bbolt"
 )
 

go.mod

@@ -5,6 +5,9 @@ go 1.12
 require (
 	github.com/go-bindata/go-bindata v3.1.2+incompatible // indirect
 	github.com/gorilla/mux v1.7.3
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.1 // indirect
 	github.com/pkg/errors v0.8.1
+	github.com/prometheus/client_golang v1.1.0
 	go.etcd.io/bbolt v1.3.3
 )

go.sum

@@ -1,10 +1,76 @@
+github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
+github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-bindata/go-bindata v3.1.2+incompatible h1:5vjJMVhowQdPzjE1LdxyFF7YFTXg5IgGVW4gBr5IbvE=
 github.com/go-bindata/go-bindata v3.1.2+incompatible/go.mod h1:xK8Dsgwmeed+BBsSy2XTopBn/8uK2HWuGSnA11C3Joo=
+github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
+github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
+github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V4qmtdjCk=
+github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
+github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.2 h1:6nsPYzhq5kReh6QImI3k5qWzO4PEbvbIW2cwSfR/6xs=
+github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/gorilla/mux v1.7.3 h1:gnP5JzjVOuiZD07fKKToCAOjS0yOpj/qPETTXCCS6hw=
 github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/joomcode/errorx v1.0.0 h1:RJAKLTy1Sv2Tszhu14m5RZP4VGRlhXutG/XlL1En5VM=
 github.com/joomcode/errorx v1.0.0/go.mod h1:kgco15ekB6cs+4Xjzo7SPeXzx38PbJzBwbnu9qfVNHQ=
+github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
+github.com/json-iterator/go v1.1.7/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
+github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
+github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
+github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
+github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
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+github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
+github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
+github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
+github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
+github.com/prometheus/client_golang v1.1.0 h1:BQ53HtBmfOitExawJ6LokA4x8ov/z0SYYb0+HxJfRI8=
+github.com/prometheus/client_golang v1.1.0/go.mod h1:I1FGZT9+L76gKKOs5djB6ezCbFQP1xR9D75/vuwEF3g=
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+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
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+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 go.etcd.io/bbolt v1.3.3 h1:MUGmc65QhB3pIlaQ5bB4LwqSj6GIonVJXpZiaKNyaKk=
 go.etcd.io/bbolt v1.3.3/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

handlers.go

@@ -13,11 +13,9 @@ import (
 	"net/url"
 	"time"
 
-	gobmarsh "gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
+	"gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
-
+	"github.com/gorilla/mux"
-	mux "github.com/gorilla/mux"
+	"github.com/pkg/errors"
-	errors "github.com/pkg/errors"
-
 	bolt "go.etcd.io/bbolt"
 )
 

metrics.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"time"
+
+	bolt "go.etcd.io/bbolt"
+
+	"github.com/gorilla/mux"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	METRICS_ADDR = "127.0.0.1:58614"
+)
+
+var (
+	shortenUrlsTotal = promauto.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: "rushlink",
+		Subsystem: "shorten",
+		Name:      "urls_total",
+		Help:      "The current amount of shortened urls in the database.",
+	}, func() float64 {
+		var metric float64
+		if err := db.View(func(tx *bolt.Tx) error {
+			bucket := tx.Bucket([]byte("shorten"))
+			if bucket == nil {
+				return errors.New("bucket 'shorten' could not be found")
+			}
+			metric = float64(bucket.Stats().KeyN)
+			return nil
+		}); err != nil {
+			log.Printf("error: %v", errors.Wrap(err, "fetching shorten_urls_total metric"))
+			return 0
+		}
+		return metric
+	})
+)
+
+func startMetricsServer() {
+	router := mux.NewRouter()
+	router.Handle("/metrics", promhttp.Handler()).Methods("GET")
+	srv := &http.Server{
+		Handler:      router,
+		Addr:         METRICS_ADDR,
+		WriteTimeout: 15 * time.Second,
+		ReadTimeout:  15 * time.Second,
+	}
+	log.Fatal(srv.ListenAndServe())
+}

rushlink.go

@@ -6,8 +6,8 @@ import (
 	"net/http"
 	"time"
 
-	mux "github.com/gorilla/mux"
+	"github.com/gorilla/mux"
-	errors "github.com/pkg/errors"
+	"github.com/pkg/errors"
 	bolt "go.etcd.io/bbolt"
 )
 
@@ -39,6 +39,9 @@ func main() {
 		log.Fatal(decoratedErr)
 	}
 
+	// Export prometheus metrics
+	go startMetricsServer()
+
 	// Initialize Gorilla router
 	router := mux.NewRouter()
 	router.HandleFunc("/", indexGetHandler).Methods("GET")