Serving SRV targets and getting all nodes in single request

README.md

@@ -100,6 +100,19 @@ If your URI is prefixed by mongodb:// or mongodb+srv:// schema, any host not pre
 --mongodb.uri=mongodb+srv://user:pass@host1:27017,host2:27017,host3:27017/admin,mongodb://user2:pass2@host4:27018/admin
 ```
 
+You can use the --split-cluster option to split all cluster nodes into separate targets. This mode is useful when cluster nodes are defined as SRV records and the mongodb_exporter is running with mongodb+srv domain specified. In this case SRV records will be queried upon mongodb_exporter start and each cluster node can be queried using the **target** parameter of multitarget endpoint. 
+
+#### Overall targets request endpoint
+
+There is an overall targets endpoint **/scrapeall** that queries all the targets in one request. It can be used to store multiple node metrics without separate target requests. In this case, each node metric will have a **instance** label containing the node name as a host:port pair (or just host if no port was not specified). For example, for mongodb_exporter running with the options:
+```
+--mongodb.uri="mongodb://host1:27015,host2:27016" --split-cluster=true
+``` 
+we get metrics like this:
+```
+mongodb_up{instance="host1:27015"} 1
+mongodb_up{instance="host2:27016"} 1
+```
 
 #### Enabling collstats metrics gathering
 `--mongodb.collstats-colls` receives a list of databases and collections to monitor using collstats.

exporter/exporter.go

@@ -76,7 +76,8 @@
 	IndexStatsCollections []string
 	Logger                *logrus.Logger
 
-	URI string
+	URI      string
+	NodeName string
 }
 
 var (
@@ -282,36 +283,7 @@
 		ctx, cancel := context.WithTimeout(r.Context(), time.Duration(seconds)*time.Second)
 		defer cancel()
 
-		filters := r.URL.Query()["collect[]"]
-
-		requestOpts := Opts{}
-
-		if len(filters) == 0 {
-			requestOpts = *e.opts
-		}
-
-		for _, filter := range filters {
-			switch filter {
-			case "diagnosticdata":
-				requestOpts.EnableDiagnosticData = true
-			case "replicasetstatus":
-				requestOpts.EnableReplicasetStatus = true
-			case "dbstats":
-				requestOpts.EnableDBStats = true
-			case "topmetrics":
-				requestOpts.EnableTopMetrics = true
-			case "currentopmetrics":
-				requestOpts.EnableCurrentopMetrics = true
-			case "indexstats":
-				requestOpts.EnableIndexStats = true
-			case "collstats":
-				requestOpts.EnableCollStats = true
-			case "profile":
-				requestOpts.EnableProfile = true
-			case "shards":
-				requestOpts.EnableShards = true
-			}
-		}
+		requestOpts := GetRequestOpts(r.URL.Query()["collect[]"], e.opts)
 
 		client, err = e.getClient(ctx)
 		if err != nil {
@@ -364,6 +336,40 @@
 	})
 }
 
+// GetRequestOpts makes exporter.Opts structure from request filters and default options.
+func GetRequestOpts(filters []string, defaultOpts *Opts) Opts {
+	requestOpts := Opts{}
+
+	if len(filters) == 0 {
+		requestOpts = *defaultOpts
+	}
+
+	for _, filter := range filters {
+		switch filter {
+		case "diagnosticdata":
+			requestOpts.EnableDiagnosticData = true
+		case "replicasetstatus":
+			requestOpts.EnableReplicasetStatus = true
+		case "dbstats":
+			requestOpts.EnableDBStats = true
+		case "topmetrics":
+			requestOpts.EnableTopMetrics = true
+		case "currentopmetrics":
+			requestOpts.EnableCurrentopMetrics = true
+		case "indexstats":
+			requestOpts.EnableIndexStats = true
+		case "collstats":
+			requestOpts.EnableCollStats = true
+		case "profile":
+			requestOpts.EnableProfile = true
+		case "shards":
+			requestOpts.EnableShards = true
+		}
+	}
+
+	return requestOpts
+}
+
 func connect(ctx context.Context, opts *Opts) (*mongo.Client, error) {
 	clientOpts, err := dsn_fix.ClientOptionsForDSN(opts.URI)
 	if err != nil {

exporter/gatherer_wrapper.go

@@ -0,0 +1,59 @@
+// mongodb_exporter
+// Copyright (C) 2017 Percona LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exporter
+
+import (
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	io_prometheus_client "github.com/prometheus/client_model/go"
+)
+
+// GathererWrapped is a wrapper for prometheus.Gatherer that adds labels to all metrics.
+type GathererWrapped struct {
+	originalGatherer prometheus.Gatherer
+	labels           prometheus.Labels
+}
+
+// NewGathererWrapper creates a new GathererWrapped with the given Gatherer and additional labels.
+func NewGathererWrapper(gs prometheus.Gatherer, labels prometheus.Labels) *GathererWrapped {
+	return &GathererWrapped{
+		originalGatherer: gs,
+		labels:           labels,
+	}
+}
+
+// Gather implements prometheus.Gatherer interface.
+func (g *GathererWrapped) Gather() ([]*io_prometheus_client.MetricFamily, error) {
+	metrics, err := g.originalGatherer.Gather()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to gather metrics")
+	}
+
+	for _, metric := range metrics {
+		for _, m := range metric.GetMetric() {
+			for k, v := range g.labels {
+				v := v
+				k := k
+				m.Label = append(m.Label, &io_prometheus_client.LabelPair{
+					Name:  &k,
+					Value: &v,
+				})
+			}
+		}
+	}
+
+	return metrics, nil
+}

exporter/multi_target_test.go

@@ -17,7 +17,11 @@ package exporter
 
 import (
 	"fmt"
+	"io"
 	"net"
+	"net/http"
+	"net/http/httptest"
+	"regexp"
 	"testing"
 
 	"github.com/sirupsen/logrus"
@@ -70,3 +74,61 @@ func TestMultiTarget(t *testing.T) {
 		assert.HTTPBodyContains(t, multiTargetHandler(serverMap), "GET", fmt.Sprintf("?target=%s", opt.URI), nil, expected[sn])
 	}
 }
+
+func TestOverallHandler(t *testing.T) {
+	t.Parallel()
+
+	opts := []*Opts{
+		{
+			NodeName:         "standalone",
+			URI:              fmt.Sprintf("mongodb://127.0.0.1:%s", tu.GetenvDefault("TEST_MONGODB_STANDALONE_PORT", "27017")),
+			DirectConnect:    true,
+			ConnectTimeoutMS: 1000,
+		},
+		{
+			NodeName:         "s1",
+			URI:              fmt.Sprintf("mongodb://127.0.0.1:%s", tu.GetenvDefault("TEST_MONGODB_S1_PRIMARY_PORT", "17001")),
+			DirectConnect:    true,
+			ConnectTimeoutMS: 1000,
+		},
+		{
+			NodeName:         "s2",
+			URI:              fmt.Sprintf("mongodb://127.0.0.1:%s", tu.GetenvDefault("TEST_MONGODB_S2_PRIMARY_PORT", "17004")),
+			DirectConnect:    true,
+			ConnectTimeoutMS: 1000,
+		},
+		{
+			NodeName:         "s3",
+			URI:              "mongodb://127.0.0.1:12345",
+			DirectConnect:    true,
+			ConnectTimeoutMS: 1000,
+		},
+	}
+	expected := []*regexp.Regexp{
+		regexp.MustCompile(`mongodb_up{[^\}]*instance="standalone"[^\}]*} 1\n`),
+		regexp.MustCompile(`mongodb_up{[^\}]*instance="s1"[^\}]*} 1\n`),
+		regexp.MustCompile(`mongodb_up{[^\}]*instance="s2"[^\}]*} 1\n`),
+		regexp.MustCompile(`mongodb_up{[^\}]*instance="s3"[^\}]*} 0\n`),
+	}
+	exporters := make([]*Exporter, len(opts))
+
+	logger := logrus.New()
+
+	for i, opt := range opts {
+		exporters[i] = New(opt)
+	}
+
+	rr := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	OverallTargetsHandler(exporters, logger)(rr, req)
+	res := rr.Result()
+	resBody, _ := io.ReadAll(res.Body)
+	err := res.Body.Close()
+	assert.NoError(t, err)
+
+	assert.Equal(t, http.StatusOK, res.StatusCode)
+
+	for _, expected := range expected {
+		assert.Regexp(t, expected, string(resBody))
+	}
+}

exporter/seedlist.go

@@ -0,0 +1,88 @@
+// mongodb_exporter
+// Copyright (C) 2017 Percona LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exporter
+
+import (
+	"net"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+)
+
+// GetSeedListFromSRV converts mongodb+srv URI to flat connection string.
+func GetSeedListFromSRV(uri string, log *logrus.Logger) string {
+	uriParsed, err := url.Parse(uri)
+	if err != nil {
+		log.Fatalf("Failed to parse URI %s: %v", uri, err)
+	}
+
+	cname, srvRecords, err := net.LookupSRV("mongodb", "tcp", uriParsed.Hostname())
+	if err != nil {
+		log.Errorf("Failed to lookup SRV records for %s: %v", uri, err)
+		return uri
+	}
+
+	if len(srvRecords) == 0 {
+		log.Errorf("No SRV records found for %s", uri)
+		return uri
+	}
+
+	queryString := uriParsed.RawQuery
+
+	txtRecords, err := net.LookupTXT(uriParsed.Hostname())
+	if err != nil {
+		log.Errorf("Failed to lookup TXT records for %s: %v", cname, err)
+	}
+	if len(txtRecords) > 1 {
+		log.Errorf("Multiple TXT records found for %s, thus were not applied", cname)
+	}
+	if len(txtRecords) == 1 {
+		// We take connection parameters from the TXT record
+		uriParams, err := url.ParseQuery(txtRecords[0])
+		if err != nil {
+			log.Errorf("Failed to parse TXT record %s: %v", txtRecords[0], err)
+		} else {
+			// Override connection parameters with ones from URI query string
+			for p, v := range uriParsed.Query() {
+				uriParams[p] = v
+			}
+			queryString = uriParams.Encode()
+		}
+	}
+
+	// Build final connection URI
+	servers := make([]string, len(srvRecords))
+	for i, srv := range srvRecords {
+		servers[i] = net.JoinHostPort(strings.TrimSuffix(srv.Target, "."), strconv.FormatUint(uint64(srv.Port), 10))
+	}
+	uri = "mongodb://"
+	if uriParsed.User != nil {
+		uri += uriParsed.User.String() + "@"
+	}
+	uri += strings.Join(servers, ",")
+	if uriParsed.Path != "" {
+		uri += uriParsed.Path
+	} else {
+		uri += "/"
+	}
+	if queryString != "" {
+		uri += "?" + queryString
+	}
+
+	return uri
+}

exporter/seedlist_test.go

@@ -0,0 +1,52 @@
+// mongodb_exporter
+// Copyright (C) 2017 Percona LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exporter
+
+import (
+	"net"
+	"testing"
+
+	"github.com/foxcpp/go-mockdns"
+	"github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/percona/mongodb_exporter/internal/tu"
+)
+
+func TestGetSeedListFromSRV(t *testing.T) {
+	// Can't run in parallel because it patches the net.DefaultResolver
+
+	log := logrus.New()
+	srv := tu.SetupFakeResolver()
+
+	defer func(t *testing.T) {
+		t.Helper()
+		err := srv.Close()
+		assert.NoError(t, err)
+	}(t)
+	defer mockdns.UnpatchNet(net.DefaultResolver)
+
+	tests := map[string]string{
+		"mongodb+srv://server.example.com":                                         "mongodb://mongo1.example.com:17001,mongo2.example.com:17002,mongo3.example.com:17003/?authSource=admin",
+		"mongodb+srv://user:pass@server.example.com?replicaSet=rs0&authSource=db0": "mongodb://user:pass@mongo1.example.com:17001,mongo2.example.com:17002,mongo3.example.com:17003/?authSource=db0&replicaSet=rs0",
+		"mongodb+srv://unexistent.com":                                             "mongodb+srv://unexistent.com",
+	}
+
+	for uri, expected := range tests {
+		actual := GetSeedListFromSRV(uri, log)
+		assert.Equal(t, expected, actual)
+	}
+}