[Feature] Add new API exporter (#19)

Author: ajanikow

.gitignore

@@ -1,4 +1,4 @@
 .gobuild
 bin
 arangodb-exporter
-
+vendor

Dockerfile.scratch

@@ -1,4 +1,5 @@
-FROM scratch
+ARG BASE_IMAGE=scratch
+FROM ${BASE_IMAGE}
 
 ARG VERSION
 LABEL name="arangodb-exporter" \

Dockerfile.ubi

@@ -0,0 +1,4 @@
+ARG IMAGE=registry.access.redhat.com/ubi8/ubi-minimal:8.0
+FROM ${IMAGE}
+
+RUN microdnf update && microdnf clean all

Makefile

@@ -87,17 +87,24 @@ $(GOBUILDDIR):
 run-tests: 
 	go test $(REPOPATH)
 
+docker-ubi-base: check-vars
+	docker build --no-cache -t $(DOCKERIMAGE)-base-image-ubi -f Dockerfile.ubi .
+
+docker-ubi: docker-ubi-base build
+	for arch in amd64; do \
+		docker build --build-arg "GOARCH=$$arch" --build-arg "VERSION=$(VERSION_MAJOR_MINOR_PATCH)" -t $(DOCKERIMAGE)-ubi --build-arg "BASE_IMAGE=$(DOCKERIMAGE)-base-image-ubi" -f Dockerfile.scratch . ; \
+		docker push $(DOCKERIMAGE)-ubi ; \
+	done
+
+ifndef IGNORE_UBI
+docker: docker-ubi
+endif
+
 docker: check-vars build
 	for arch in $(ARCHS); do \
 		docker build --build-arg "GOARCH=$$arch" --build-arg "VERSION=$(VERSION_MAJOR_MINOR_PATCH)" -t $(DOCKERIMAGE)-$$arch -f Dockerfile.scratch . ; \
 		docker push $(DOCKERIMAGE)-$$arch ; \
 	done
-	for arch in amd64; do \
-		sed -e 's|FROM scratch|FROM $(UBI)|' Dockerfile.scratch > Dockerfile.ubi ; \
-		docker build --build-arg "GOARCH=$$arch" --build-arg "VERSION=$(VERSION_MAJOR_MINOR_PATCH)" -t $(DOCKERIMAGE)-ubi -f Dockerfile.ubi . ; \
-		rm -f Dockerfile.ubi ; \
-		docker push $(DOCKERIMAGE)-ubi ; \
-	done
 	DOCKER_CLI_EXPERIMENTAL=enabled docker manifest create --amend $(DOCKERIMAGE) $(foreach arch,$(ARCHS),$(DOCKERIMAGE)-$(arch)) $(DOCKERIMAGE)-ubi
 	DOCKER_CLI_EXPERIMENTAL=enabled docker manifest push $(DOCKERIMAGE)
 

README.md

@@ -18,6 +18,20 @@ This results in an ArangoDB Exporter exposing all statistics of
 the ArangoDB server (running at `http://<your-database-host>:8529`)
 at `http://<your-host-ip>:9101/metrics`.
 
+## Exporter modes
+
+### internal
+
+Use internal metrics exporter mode for ArangoDB < 3.6.0
+
+In this mode metrics are calculated on ArangoDB Exporter side
+
+### passthru
+
+Expose ArangoDB metrics for ArangoDB >= 3.6.0
+
+In this mode metrics provided by ArangoDB `_admin/metrics` are exposed on Exporter port.
+
 ## Running in Docker
 
 To run the ArangoDB Exporter in docker, use an image such as

main.go

@@ -37,6 +37,13 @@ import (
 	"github.com/spf13/cobra"
 )
 
+type ExporterMode string
+
+const (
+	ModeInternal ExporterMode = "internal"
+	ModePassthru ExporterMode = "passthru"
+)
+
 var (
 	projectVersion = "dev"
 	projectBuild   = "dev"
@@ -50,6 +57,7 @@ var (
 	serverOptions   ServerConfig
 	arangodbOptions struct {
 		endpoint  string
+		mode      string
 		jwtSecret string
 		jwtFile   string
 		timeout   time.Duration
@@ -67,6 +75,8 @@ func init() {
 	f.StringVar(&arangodbOptions.jwtFile, "arangodb.jwt-file", "", "File containing the JWT for authentication with ArangoDB server")
 	f.DurationVar(&arangodbOptions.timeout, "arangodb.timeout", time.Second*15, "Timeout of statistics requests for ArangoDB")
 
+	f.StringVar(&arangodbOptions.mode, "mode", "internal", "Mode for ArangoDB exporter. Internal - use internal, old mode of metrics calculation (default). Passthru - expose ArangoD metrics directly, using proper authentication.")
+
 	f.MarkDeprecated("arangodb.jwtsecret", "please use --arangodb.jwt-file instead")
 }
 
@@ -91,20 +101,28 @@ func cmdMainRun(cmd *cobra.Command, args []string) {
 			log.Fatal(err)
 		}
 	}
-
-	exporter, err := NewExporter(arangodbOptions.endpoint, token, false, arangodbOptions.timeout)
-	if err != nil {
-		log.Fatal(err)
+	mux := http.NewServeMux()
+	switch ExporterMode(arangodbOptions.mode) {
+	case ModePassthru:
+		passthru, err := NewPassthru(arangodbOptions.endpoint, token, false, arangodbOptions.timeout)
+		if err != nil {
+			log.Fatal(err)
+		}
+		mux.Handle("/metrics", passthru)
+	default:
+		exporter, err := NewExporter(arangodbOptions.endpoint, token, false, arangodbOptions.timeout)
+		if err != nil {
+			log.Fatal(err)
+		}
+		prometheus.MustRegister(exporter)
+		version.Version = projectVersion
+		version.Revision = projectBuild
+		prometheus.MustRegister(version.NewCollector("arangodb_exporter"))
+		mux.Handle("/metrics", prometheus.Handler())
 	}
-	prometheus.MustRegister(exporter)
-	version.Version = projectVersion
-	version.Revision = projectBuild
-	prometheus.MustRegister(version.NewCollector("arangodb_exporter"))
 
 	log.Infoln("Listening on", serverOptions.Address)
 
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", prometheus.Handler())
 	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`<html>
              <head><title>ArangoDB Exporter</title></head>

passthru.go

@@ -0,0 +1,102 @@
+//
+// DISCLAIMER
+//
+// Copyright 2018 ArangoDB GmbH, Cologne, Germany
+//
+// 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.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+// Author Adam Janikowski
+//
+
+package main
+
+import (
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+var _ http.Handler = &passthru{}
+
+func NewPassthru(arangodbEndpoint, jwt string, sslVerify bool, timeout time.Duration) (http.Handler, error) {
+	transport := &http.Transport{}
+
+	req, err := http.NewRequest("GET", fmt.Sprintf("%s/_admin/metrics", arangodbEndpoint), nil)
+	if err != nil {
+		return nil, maskAny(err)
+	}
+
+	if !sslVerify {
+		transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
+	}
+
+	if jwt != "" {
+		hdr, err := CreateArangodJwtAuthorizationHeader(jwt)
+		if err != nil {
+			return nil, maskAny(err)
+		}
+		req.Header.Add("Authorization", hdr)
+	}
+
+	client := &http.Client{
+		Transport: transport,
+		Timeout:   timeout,
+	}
+
+	return &passthru{
+		client:  client,
+		request: req,
+	}, nil
+}
+
+type passthru struct {
+	request *http.Request
+	client  *http.Client
+}
+
+func (p passthru) get() (*http.Response, error) {
+	return p.client.Do(p.request)
+}
+
+func (p passthru) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+	data, err := p.get()
+
+	if err != nil {
+		// Ignore error
+		resp.WriteHeader(http.StatusInternalServerError)
+		resp.Write([]byte(err.Error()))
+		return
+	}
+
+	if data.Body == nil {
+		// Ignore error
+		resp.WriteHeader(http.StatusInternalServerError)
+		resp.Write([]byte("Body is empty"))
+		return
+	}
+
+	defer data.Body.Close()
+
+	_, err = io.Copy(resp, data.Body)
+
+	if err != nil {
+		// Ignore error
+		resp.WriteHeader(http.StatusInternalServerError)
+		resp.Write([]byte("Unable to write body"))
+		return
+	}
+}