Enhance NodeExporterPath JSON option to pass additional node_exporter arguments

util/metrics/reporter.go

@@ -23,6 +23,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 	// logging imports metrics so that we can have metrics about logging, which is more important than the four Debug lines we had here logging about metrics. TODO: find a more clever cycle resolution
@@ -177,6 +178,30 @@ func (reporter *MetricReporter) tryDetachNodeExporter() {
 	}
 }
 
+// parseNodeExporterArgs parses the NodeExporterPath configuration string to extract Node Exporter's arguments.
+func parseNodeExporterArgs(nodeExporterPath string, nodeExporterListenAddress string, nodeExporterMetricsPath string) []string {
+	whitespaceRE := regexp.MustCompile(`\s+`)
+	listenAddressRE := regexp.MustCompile(`--web.listen-address=(.+)`)
+	telemetryPathRE := regexp.MustCompile(`--web.telemetry-path=(.+)`)
+	vargs := whitespaceRE.Split(nodeExporterPath, -1)
+	temp := vargs[:0]
+	for _, varg := range vargs {
+		if listenAddressRE.MatchString(varg) {
+			nodeExporterListenAddress = listenAddressRE.FindStringSubmatch(varg)[1]
+		} else if telemetryPathRE.MatchString(varg) {
+			nodeExporterMetricsPath = telemetryPathRE.FindStringSubmatch(varg)[1]
+		} else if varg == "" {
+			continue
+		} else {
+			temp = append(temp, varg)
+		}
+	}
+	vargs = append(vargs[:len(temp)],
+		"--web.listen-address="+nodeExporterListenAddress,
+		"--web.telemetry-path="+nodeExporterMetricsPath)
+	return vargs
+}
+
 func (reporter *MetricReporter) tryInvokeNodeExporter(ctx context.Context) {
 	var err error
 	if nil == reporter.neSync {
@@ -205,10 +230,7 @@ func (reporter *MetricReporter) tryInvokeNodeExporter(ctx context.Context) {
 			os.Stderr}
 	}
 	// prepare the vargs that the new process is going to have.
-	vargs := []string{
-		reporter.serviceConfig.NodeExporterPath,
-		"--web.listen-address=" + reporter.serviceConfig.NodeExporterListenAddress,
-		"--web.telemetry-path=" + nodeExporterMetricsPath}
+	vargs := parseNodeExporterArgs(reporter.serviceConfig.NodeExporterPath, reporter.serviceConfig.NodeExporterListenAddress, nodeExporterMetricsPath)
 	// launch the process
 	proc, err := os.StartProcess(vargs[0], vargs, &neAttributes)
 	if err != nil {

util/metrics/reporter_test.go

@@ -0,0 +1,52 @@
+// Copyright (C) 2019 Algorand, Inc.
+// This file is part of go-algorand
+//
+// go-algorand is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// go-algorand is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with go-algorand.  If not, see <https://www.gnu.org/licenses/>.
+
+package metrics
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseNodeExporterArgs(t *testing.T) {
+	passTestcases := map[string][]string{
+		"./node_exporter":                                                                           []string{"./node_exporter", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"},                                               // simple case
+		"./node_exporter --collector.systemd":                                                       []string{"./node_exporter", "--collector.systemd", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"},                        // extended case with one argument
+		"./node_exporter random --collector.systemd":                                                []string{"./node_exporter", "random", "--collector.systemd", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"},              // extended case multiple arguments
+		"/usr/bin/local/node_exporter --collector.systemd random":                                   []string{"/usr/bin/local/node_exporter", "--collector.systemd", "random", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"}, // other executable path
+		" /usr/bin/local/node_exporter --collector.systemd random":                                  []string{"/usr/bin/local/node_exporter", "--collector.systemd", "random", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"}, // space at beginning of option
+		"./node_exporter --web.telemetry-path=/foobar --web.listen-address=:9090 ":                  []string{"./node_exporter", "--web.listen-address=:9090", "--web.telemetry-path=/foobar"},                                                // overriding defaults
+		"./node_exporter --web.listen-address=:8080  --web.telemetry-path=/barfoo":                  []string{"./node_exporter", "--web.listen-address=:8080", "--web.telemetry-path=/barfoo"},                                                // overriding defaults different order and multiple spaces
+		"./node_exporter --web.listen-address=:9090  --collector.proc --web.telemetry-path=/foobar": []string{"./node_exporter", "--collector.proc", "--web.listen-address=:9090", "--web.telemetry-path=/foobar"},                            // argument in between the persistent ones
+		"./node_exporter --web.listen-address=:9090  --collector.test  --collector.systemd ":        []string{"./node_exporter", "--collector.test", "--collector.systemd", "--web.listen-address=:9090", "--web.telemetry-path=/metrics"},    // argument after persistent one
+	}
+	for test, expected := range passTestcases {
+		vargs := parseNodeExporterArgs(test, ":9100", "/metrics")
+		require.Equalf(t, vargs, expected, "Argument parsing did not result in expected value for: %v, got: %v, want: %v.", test, vargs, expected)
+	}
+
+	failTestcases := map[string][]string{
+		"./node_exporter":                                          []string{"./node_exporter", "--web.listen-address=:9090", "--web.telemetry-path=/foobar"},                                                 // default arguments not being passed
+		"./node_exporter --collector.systemd":                      []string{"./node_exporter", "--web.listen-address=:9100", "--web.telemetry-path=/metrics", "--collector.systemd"},                         // incorrect order of persistent and added options
+		"./node_exporter random --collector.systemd":               []string{"./node_exporter", "--collector.systemd", "random", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"},               // reversed order of persistent options
+		" /usr/bin/local/node_exporter --collector.systemd random": []string{" /usr/bin/local/node_exporter", "--collector.systemd", "random", "--web.listen-address=:9100", "--web.telemetry-path=/metrics"}, // space at beginning of option preserved
+	}
+	for test, notexpected := range failTestcases {
+		vargs := parseNodeExporterArgs(test, ":9100", "/metrics")
+		require.NotEqualf(t, vargs, notexpected, "Argument parsing did result in expected value for: %v, got: %v, want: %v.", test, vargs, notexpected)
+	}
+}