Add support for multiple listening addresses

Fixes #9105 Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu> Signed-off-by: Julien <roidelapluie@o11y.eu>
2024-11-09 23:24:05 -08:00 · 2024-08-13 14:34:26 +02:00 · 2024-08-13 14:34:26 +02:00 · 9b5e7623f4
parent 82c4599ebe
commit 9b5e7623f4
9 changed files with 420 additions and 94 deletions
--- a/cmd/prometheus/main.go
+++ b/cmd/prometheus/main.go
@ -297,8 +297,8 @@ func main() {
 	a.Flag("config.file", "Prometheus configuration file path.").
 		Default("prometheus.yml").StringVar(&cfg.configFile)

-	a.Flag("web.listen-address", "Address to listen on for UI, API, and telemetry.").
-		Default("0.0.0.0:9090").StringVar(&cfg.web.ListenAddress)
+	a.Flag("web.listen-address", "Address to listen on for UI, API, and telemetry. Can be repeated.").
+		Default("0.0.0.0:9090").StringsVar(&cfg.web.ListenAddresses)

 	a.Flag("auto-gomemlimit.ratio", "The ratio of reserved GOMEMLIMIT memory to the detected maximum container or system memory").
 		Default("0.9").FloatVar(&cfg.memlimitRatio)
@ -312,7 +312,7 @@ func main() {
 		"Maximum duration before timing out read of the request, and closing idle connections.").
 		Default("5m").SetValue(&cfg.webTimeout)

-	a.Flag("web.max-connections", "Maximum number of simultaneous connections.").
+	a.Flag("web.max-connections", "Maximum number of simultaneous connections across all listeners.").
 		Default("512").IntVar(&cfg.web.MaxConnections)

 	a.Flag("web.external-url",
@ -544,7 +544,7 @@ func main() {
 		localStoragePath = cfg.agentStoragePath
 	}

-	cfg.web.ExternalURL, err = computeExternalURL(cfg.prometheusURL, cfg.web.ListenAddress)
+	cfg.web.ExternalURL, err = computeExternalURL(cfg.prometheusURL, cfg.web.ListenAddresses[0])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, fmt.Errorf("parse external URL %q: %w", cfg.prometheusURL, err))
 		os.Exit(2)
@ -990,9 +990,9 @@ func main() {
 		})
 	}

-	listener, err := webHandler.Listener()
+	listeners, err := webHandler.Listeners()
 	if err != nil {
-		level.Error(logger).Log("msg", "Unable to start web listener", "err", err)
+		level.Error(logger).Log("msg", "Unable to start web listeners", "err", err)
 		os.Exit(1)
 	}

@ -1287,7 +1287,7 @@ func main() {
 		// Web handler.
 		g.Add(
 			func() error {
-				if err := webHandler.Run(ctxWeb, listener, *webConfig); err != nil {
+				if err := webHandler.Run(ctxWeb, listeners, *webConfig); err != nil {
 					return fmt.Errorf("error starting web server: %w", err)
 				}
 				return nil
--- a/docs/command-line/prometheus.md
+++ b/docs/command-line/prometheus.md
@ -15,11 +15,11 @@ The Prometheus monitoring server
 | <code class="text-nowrap">-h</code>, <code class="text-nowrap">--help</code> | Show context-sensitive help (also try --help-long and --help-man). |  |
 | <code class="text-nowrap">--version</code> | Show application version. |  |
 | <code class="text-nowrap">--config.file</code> | Prometheus configuration file path. | `prometheus.yml` |
-| <code class="text-nowrap">--web.listen-address</code> | Address to listen on for UI, API, and telemetry. | `0.0.0.0:9090` |
+| <code class="text-nowrap">--web.listen-address</code> <code class="text-nowrap">...<code class="text-nowrap"> | Address to listen on for UI, API, and telemetry. Can be repeated. | `0.0.0.0:9090` |
 | <code class="text-nowrap">--auto-gomemlimit.ratio</code> | The ratio of reserved GOMEMLIMIT memory to the detected maximum container or system memory | `0.9` |
 | <code class="text-nowrap">--web.config.file</code> | [EXPERIMENTAL] Path to configuration file that can enable TLS or authentication. |  |
 | <code class="text-nowrap">--web.read-timeout</code> | Maximum duration before timing out read of the request, and closing idle connections. | `5m` |
-| <code class="text-nowrap">--web.max-connections</code> | Maximum number of simultaneous connections. | `512` |
+| <code class="text-nowrap">--web.max-connections</code> | Maximum number of simultaneous connections across all listeners. | `512` |
 | <code class="text-nowrap">--web.external-url</code> | The URL under which Prometheus is externally reachable (for example, if Prometheus is served via a reverse proxy). Used for generating relative and absolute links back to Prometheus itself. If the URL has a path portion, it will be used to prefix all HTTP endpoints served by Prometheus. If omitted, relevant URL components will be derived automatically. |  |
 | <code class="text-nowrap">--web.route-prefix</code> | Prefix for the internal routes of web endpoints. Defaults to path of --web.external-url. |  |
 | <code class="text-nowrap">--web.user-assets</code> | Path to static asset directory, available at /user. |  |
@ -57,7 +57,7 @@ The Prometheus monitoring server
 | <code class="text-nowrap">--query.max-concurrency</code> | Maximum number of queries executed concurrently. Use with server mode only. | `20` |
 | <code class="text-nowrap">--query.max-samples</code> | Maximum number of samples a single query can load into memory. Note that queries will fail if they try to load more samples than this into memory, so this also limits the number of samples a query can return. Use with server mode only. | `50000000` |
 | <code class="text-nowrap">--scrape.name-escaping-scheme</code> | Method for escaping legacy invalid names when sending to Prometheus that does not support UTF-8. Can be one of "values", "underscores", or "dots". | `values` |
-| <code class="text-nowrap">--enable-feature</code> | Comma separated feature names to enable. Valid options: agent, auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, remote-write-receiver (DEPRECATED), extra-scrape-metrics, new-service-discovery-manager, auto-gomaxprocs, no-default-scrape-port, native-histograms, otlp-write-receiver, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
+| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable. Valid options: agent, auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, remote-write-receiver (DEPRECATED), extra-scrape-metrics, new-service-discovery-manager, auto-gomaxprocs, no-default-scrape-port, native-histograms, otlp-write-receiver, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
 | <code class="text-nowrap">--log.level</code> | Only log messages with the given severity or above. One of: [debug, info, warn, error] | `info` |
 | <code class="text-nowrap">--log.format</code> | Output format of log messages. One of: [logfmt, json] | `logfmt` |

--- a/docs/command-line/promtool.md
+++ b/docs/command-line/promtool.md
@ -15,7 +15,7 @@ Tooling for the Prometheus monitoring system.
 | <code class="text-nowrap">-h</code>, <code class="text-nowrap">--help</code> | Show context-sensitive help (also try --help-long and --help-man). |
 | <code class="text-nowrap">--version</code> | Show application version. |
 | <code class="text-nowrap">--experimental</code> | Enable experimental commands. |
-| <code class="text-nowrap">--enable-feature</code> | Comma separated feature names to enable (only PromQL related and no-default-scrape-port). See https://prometheus.io/docs/prometheus/latest/feature_flags/ for the options and more details. |
+| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable (only PromQL related and no-default-scrape-port). See https://prometheus.io/docs/prometheus/latest/feature_flags/ for the options and more details. |



@ -281,7 +281,7 @@ Run series query.

 | Flag | Description |
 | --- | --- |
-| <code class="text-nowrap">--match</code> | Series selector. Can be specified multiple times. |
+| <code class="text-nowrap">--match</code> <code class="text-nowrap">...<code class="text-nowrap"> | Series selector. Can be specified multiple times. |
 | <code class="text-nowrap">--start</code> | Start time (RFC3339 or Unix timestamp). |
 | <code class="text-nowrap">--end</code> | End time (RFC3339 or Unix timestamp). |

@ -309,7 +309,7 @@ Run labels query.
 | --- | --- |
 | <code class="text-nowrap">--start</code> | Start time (RFC3339 or Unix timestamp). |
 | <code class="text-nowrap">--end</code> | End time (RFC3339 or Unix timestamp). |
-| <code class="text-nowrap">--match</code> | Series selector. Can be specified multiple times. |
+| <code class="text-nowrap">--match</code> <code class="text-nowrap">...<code class="text-nowrap"> | Series selector. Can be specified multiple times. |



@ -338,7 +338,7 @@ Run queries against your Prometheus to analyze the usage pattern of certain metr
 | <code class="text-nowrap">--type</code> | Type of metric: histogram. |  |
 | <code class="text-nowrap">--duration</code> | Time frame to analyze. | `1h` |
 | <code class="text-nowrap">--time</code> | Query time (RFC3339 or Unix timestamp), defaults to now. |  |
-| <code class="text-nowrap">--match</code> | Series selector. Can be specified multiple times. |  |
+| <code class="text-nowrap">--match</code> <code class="text-nowrap">...<code class="text-nowrap"> | Series selector. Can be specified multiple times. |  |



@ -461,7 +461,7 @@ Unit tests for rules.

 | Flag | Description | Default |
 | --- | --- | --- |
-| <code class="text-nowrap">--run</code> | If set, will only run test groups whose names match the regular expression. Can be specified multiple times. |  |
+| <code class="text-nowrap">--run</code> <code class="text-nowrap">...<code class="text-nowrap"> | If set, will only run test groups whose names match the regular expression. Can be specified multiple times. |  |
 | <code class="text-nowrap">--diff</code> | [Experimental] Print colored differential output between expected & received output. | `false` |


@ -578,7 +578,7 @@ Dump samples from a TSDB.
 | <code class="text-nowrap">--sandbox-dir-root</code> | Root directory where a sandbox directory would be created in case WAL replay generates chunks. The sandbox directory is cleaned up at the end. | `data/` |
 | <code class="text-nowrap">--min-time</code> | Minimum timestamp to dump. | `-9223372036854775808` |
 | <code class="text-nowrap">--max-time</code> | Maximum timestamp to dump. | `9223372036854775807` |
-| <code class="text-nowrap">--match</code> | Series selector. Can be specified multiple times. | `{__name__=~'(?s:.*)'}` |
+| <code class="text-nowrap">--match</code> <code class="text-nowrap">...<code class="text-nowrap"> | Series selector. Can be specified multiple times. | `{__name__=~'(?s:.*)'}` |



@ -605,7 +605,7 @@ Dump samples from a TSDB.
 | <code class="text-nowrap">--sandbox-dir-root</code> | Root directory where a sandbox directory would be created in case WAL replay generates chunks. The sandbox directory is cleaned up at the end. | `data/` |
 | <code class="text-nowrap">--min-time</code> | Minimum timestamp to dump. | `-9223372036854775808` |
 | <code class="text-nowrap">--max-time</code> | Maximum timestamp to dump. | `9223372036854775807` |
-| <code class="text-nowrap">--match</code> | Series selector. Can be specified multiple times. | `{__name__=~'(?s:.*)'}` |
+| <code class="text-nowrap">--match</code> <code class="text-nowrap">...<code class="text-nowrap"> | Series selector. Can be specified multiple times. | `{__name__=~'(?s:.*)'}` |



--- a/go.mod
+++ b/go.mod
@ -75,7 +75,6 @@ require (
 	go.uber.org/automaxprocs v1.5.3
 	go.uber.org/goleak v1.3.0
 	go.uber.org/multierr v1.11.0
-	golang.org/x/net v0.27.0
 	golang.org/x/oauth2 v0.21.0
 	golang.org/x/sync v0.7.0
 	golang.org/x/sys v0.22.0
@ -190,6 +189,7 @@ require (
 	golang.org/x/crypto v0.25.0 // indirect
 	golang.org/x/exp v0.0.0-20240119083558-1b970713d09a // indirect
 	golang.org/x/mod v0.19.0 // indirect
+	golang.org/x/net v0.27.0 // indirect
 	golang.org/x/term v0.22.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240730163845-b1a4ccb954bf // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
--- a/util/documentcli/documentcli.go
+++ b/util/documentcli/documentcli.go
@ -23,6 +23,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"reflect"
 	"strings"

 	"github.com/alecthomas/kingpin/v2"
@ -75,6 +76,16 @@ func createFlagRow(flag *kingpin.FlagModel) []string {
 		name = fmt.Sprintf(`<code class="text-nowrap">-%c</code>, <code class="text-nowrap">--%s</code>`, flag.Short, flag.Name)
 	}

+	valueType := reflect.TypeOf(flag.Value)
+	if valueType.Kind() == reflect.Ptr {
+		valueType = valueType.Elem()
+	}
+	if valueType.Kind() == reflect.Struct {
+		if _, found := valueType.FieldByName("slice"); found {
+			name = fmt.Sprintf(`%s <code class="text-nowrap">...<code class="text-nowrap">`, name)
+		}
+	}
+
 	return []string{name, strings.ReplaceAll(flag.Help, "|", `\|`), defaultVal}
 }

--- a/util/netconnlimit/netconnlimit.go
+++ b/util/netconnlimit/netconnlimit.go
@ -0,0 +1,97 @@
+// Copyright 2024 The Prometheus Authors
+// Based on golang.org/x/net/netutil:
+//   Copyright 2013 The Go Authors
+// 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 netconnlimit provides network utility functions for limiting
+// simultaneous connections across multiple listeners.
+package netconnlimit
+
+import (
+	"net"
+	"sync"
+)
+
+// NewSharedSemaphore creates and returns a new semaphore channel that can be used
+// to limit the number of simultaneous connections across multiple listeners.
+func NewSharedSemaphore(n int) chan struct{} {
+	return make(chan struct{}, n)
+}
+
+// SharedLimitListener returns a listener that accepts at most n simultaneous
+// connections across multiple listeners using the provided shared semaphore.
+func SharedLimitListener(l net.Listener, sem chan struct{}) net.Listener {
+	return &sharedLimitListener{
+		Listener: l,
+		sem:      sem,
+		done:     make(chan struct{}),
+	}
+}
+
+type sharedLimitListener struct {
+	net.Listener
+	sem       chan struct{}
+	closeOnce sync.Once     // Ensures the done chan is only closed once.
+	done      chan struct{} // No values sent; closed when Close is called.
+}
+
+// Acquire acquires the shared semaphore. Returns true if successfully
+// acquired, false if the listener is closed and the semaphore is not
+// acquired.
+func (l *sharedLimitListener) acquire() bool {
+	select {
+	case <-l.done:
+		return false
+	case l.sem <- struct{}{}:
+		return true
+	}
+}
+
+func (l *sharedLimitListener) release() { <-l.sem }
+
+func (l *sharedLimitListener) Accept() (net.Conn, error) {
+	if !l.acquire() {
+		for {
+			c, err := l.Listener.Accept()
+			if err != nil {
+				return nil, err
+			}
+			c.Close()
+		}
+	}
+
+	c, err := l.Listener.Accept()
+	if err != nil {
+		l.release()
+		return nil, err
+	}
+	return &sharedLimitListenerConn{Conn: c, release: l.release}, nil
+}
+
+func (l *sharedLimitListener) Close() error {
+	err := l.Listener.Close()
+	l.closeOnce.Do(func() { close(l.done) })
+	return err
+}
+
+type sharedLimitListenerConn struct {
+	net.Conn
+	releaseOnce sync.Once
+	release     func()
+}
+
+func (l *sharedLimitListenerConn) Close() error {
+	err := l.Conn.Close()
+	l.releaseOnce.Do(l.release)
+	return err
+}
--- a/util/netconnlimit/netconnlimit_test.go
+++ b/util/netconnlimit/netconnlimit_test.go
@ -0,0 +1,124 @@
+// Copyright 2024 The Prometheus Authors
+// 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 netconnlimit
+
+import (
+	"io"
+	"net"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSharedLimitListenerConcurrency(t *testing.T) {
+	testCases := []struct {
+		name        string
+		semCapacity int
+		connCount   int
+		expected    int // Expected number of connections processed simultaneously.
+	}{
+		{
+			name:        "Single connection allowed",
+			semCapacity: 1,
+			connCount:   3,
+			expected:    1,
+		},
+		{
+			name:        "Two connections allowed",
+			semCapacity: 2,
+			connCount:   3,
+			expected:    2,
+		},
+		{
+			name:        "Three connections allowed",
+			semCapacity: 3,
+			connCount:   3,
+			expected:    3,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			sem := NewSharedSemaphore(tc.semCapacity)
+			listener, err := net.Listen("tcp", "127.0.0.1:0")
+			require.NoError(t, err, "failed to create listener")
+			defer listener.Close()
+
+			limitedListener := SharedLimitListener(listener, sem)
+
+			var wg sync.WaitGroup
+			var activeConnCount int64
+			var mu sync.Mutex
+
+			wg.Add(tc.connCount)
+
+			// Accept connections.
+			for i := 0; i < tc.connCount; i++ {
+				go func() {
+					defer wg.Done()
+
+					conn, err := limitedListener.Accept()
+					require.NoError(t, err, "failed to accept connection")
+					defer conn.Close()
+
+					// Simulate work and track the active connection count.
+					mu.Lock()
+					activeConnCount++
+					require.LessOrEqual(t, activeConnCount, int64(tc.expected), "too many simultaneous connections")
+					mu.Unlock()
+
+					time.Sleep(100 * time.Millisecond)
+
+					mu.Lock()
+					activeConnCount--
+					mu.Unlock()
+				}()
+			}
+
+			// Create clients that attempt to connect to the listener.
+			for i := 0; i < tc.connCount; i++ {
+				go func() {
+					conn, err := net.Dial("tcp", listener.Addr().String())
+					require.NoError(t, err, "failed to connect to listener")
+					defer conn.Close()
+					_, _ = io.WriteString(conn, "hello")
+				}()
+			}
+
+			wg.Wait()
+
+			// Ensure all connections are released and semaphore is empty.
+			require.Empty(t, sem)
+		})
+	}
+}
+
+func TestSharedLimitListenerClose(t *testing.T) {
+	sem := NewSharedSemaphore(2)
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err, "failed to create listener")
+
+	limitedListener := SharedLimitListener(listener, sem)
+
+	// Close the listener and ensure it does not accept new connections.
+	err = limitedListener.Close()
+	require.NoError(t, err, "failed to close listener")
+
+	conn, err := limitedListener.Accept()
+	require.Error(t, err, "expected error on accept after listener closed")
+	if conn != nil {
+		conn.Close()
+	}
+}
--- a/web/web.go
+++ b/web/web.go
@ -49,7 +49,6 @@ import (
 	toolkit_web "github.com/prometheus/exporter-toolkit/web"
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 	"go.uber.org/atomic"
-	"golang.org/x/net/netutil"

 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/notifier"
@ -59,6 +58,7 @@ import (
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/template"
 	"github.com/prometheus/prometheus/util/httputil"
+	"github.com/prometheus/prometheus/util/netconnlimit"
 	api_v1 "github.com/prometheus/prometheus/web/api/v1"
 	"github.com/prometheus/prometheus/web/ui"
 )
@ -244,7 +244,7 @@ type Options struct {
 	Version               *PrometheusVersion
 	Flags                 map[string]string

-	ListenAddress              string
+	ListenAddresses            []string
 	CORSOrigin                 *regexp.Regexp
 	ReadTimeout                time.Duration
 	MaxConnections             int
@ -334,7 +334,7 @@ func New(logger log.Logger, o *Options) *Handler {
 		},
 		o.Flags,
 		api_v1.GlobalURLOptions{
-			ListenAddress: o.ListenAddress,
+			ListenAddress: o.ListenAddresses[0],
 			Host:          o.ExternalURL.Host,
 			Scheme:        o.ExternalURL.Scheme,
 		},
@ -566,15 +566,29 @@ func (h *Handler) Reload() <-chan chan error {
 	return h.reloadCh
 }

-// Listener creates the TCP listener for web requests.
-func (h *Handler) Listener() (net.Listener, error) {
-	level.Info(h.logger).Log("msg", "Start listening for connections", "address", h.options.ListenAddress)
+// Listeners creates the TCP listeners for web requests.
+func (h *Handler) Listeners() ([]net.Listener, error) {
+	var listeners []net.Listener
+	sem := netconnlimit.NewSharedSemaphore(h.options.MaxConnections)
+	for _, address := range h.options.ListenAddresses {
+		listener, err := h.Listener(address, sem)
+		if err != nil {
+			return listeners, err
+		}
+		listeners = append(listeners, listener)
+	}
+	return listeners, nil
+}

-	listener, err := net.Listen("tcp", h.options.ListenAddress)
+// Listener creates the TCP listener for web requests.
+func (h *Handler) Listener(address string, sem chan struct{}) (net.Listener, error) {
+	level.Info(h.logger).Log("msg", "Start listening for connections", "address", address)
+
+	listener, err := net.Listen("tcp", address)
 	if err != nil {
 		return listener, err
 	}
-	listener = netutil.LimitListener(listener, h.options.MaxConnections)
+	listener = netconnlimit.SharedLimitListener(listener, sem)

 	// Monitor incoming connections with conntrack.
 	listener = conntrack.NewListener(listener,
@ -585,10 +599,10 @@ func (h *Handler) Listener() (net.Listener, error) {
 }

 // Run serves the HTTP endpoints.
-func (h *Handler) Run(ctx context.Context, listener net.Listener, webConfig string) error {
-	if listener == nil {
+func (h *Handler) Run(ctx context.Context, listeners []net.Listener, webConfig string) error {
+	if len(listeners) == 0 {
 		var err error
-		listener, err = h.Listener()
+		listeners, err = h.Listeners()
 		if err != nil {
 			return err
 		}
@ -623,7 +637,7 @@ func (h *Handler) Run(ctx context.Context, listener net.Listener, webConfig stri

 	errCh := make(chan error, 1)
 	go func() {
-		errCh <- toolkit_web.Serve(listener, httpSrv, &toolkit_web.FlagConfig{WebConfigFile: &webConfig}, h.logger)
+		errCh <- toolkit_web.ServeMultiple(listeners, httpSrv, &toolkit_web.FlagConfig{WebConfigFile: &webConfig}, h.logger)
 	}()

 	select {
--- a/web/web_test.go
+++ b/web/web_test.go
@ -73,7 +73,7 @@ func TestReadyAndHealthy(t *testing.T) {
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))

 	opts := &Options{
-		ListenAddress:  port,
+		ListenAddresses: []string{port},
 		ReadTimeout:     30 * time.Second,
 		MaxConnections:  512,
 		Context:         nil,
@ -101,9 +101,9 @@ func TestReadyAndHealthy(t *testing.T) {

 	webHandler.config = &config.Config{}
 	webHandler.notifier = &notifier.Manager{}
-	l, err := webHandler.Listener()
+	l, err := webHandler.Listeners()
 	if err != nil {
-		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+		panic(fmt.Sprintf("Unable to start web listeners: %s", err))
 	}

 	ctx, cancel := context.WithCancel(context.Background())
@ -198,7 +198,7 @@ func TestRoutePrefix(t *testing.T) {
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))

 	opts := &Options{
-		ListenAddress:  port,
+		ListenAddresses: []string{port},
 		ReadTimeout:     30 * time.Second,
 		MaxConnections:  512,
 		Context:         nil,
@ -220,9 +220,9 @@ func TestRoutePrefix(t *testing.T) {
 	opts.Flags = map[string]string{}

 	webHandler := New(nil, opts)
-	l, err := webHandler.Listener()
+	l, err := webHandler.Listeners()
 	if err != nil {
-		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+		panic(fmt.Sprintf("Unable to start web listeners: %s", err))
 	}
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@ -300,7 +300,7 @@ func TestDebugHandler(t *testing.T) {
 	} {
 		opts := &Options{
 			RoutePrefix:     tc.prefix,
-			ListenAddress: "somehost:9090",
+			ListenAddresses: []string{"somehost:9090"},
 			ExternalURL: &url.URL{
 				Host:   "localhost.localdomain:9090",
 				Scheme: "http",
@ -325,7 +325,7 @@ func TestHTTPMetrics(t *testing.T) {
 	t.Parallel()
 	handler := New(nil, &Options{
 		RoutePrefix:     "/",
-		ListenAddress: "somehost:9090",
+		ListenAddresses: []string{"somehost:9090"},
 		ExternalURL: &url.URL{
 			Host:   "localhost.localdomain:9090",
 			Scheme: "http",
@ -381,7 +381,7 @@ func TestShutdownWithStaleConnection(t *testing.T) {
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))

 	opts := &Options{
-		ListenAddress:  port,
+		ListenAddresses: []string{port},
 		ReadTimeout:     timeout,
 		MaxConnections:  512,
 		Context:         nil,
@ -408,9 +408,9 @@ func TestShutdownWithStaleConnection(t *testing.T) {

 	webHandler.config = &config.Config{}
 	webHandler.notifier = &notifier.Manager{}
-	l, err := webHandler.Listener()
+	l, err := webHandler.Listeners()
 	if err != nil {
-		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+		panic(fmt.Sprintf("Unable to start web listeners: %s", err))
 	}

 	closed := make(chan struct{})
@ -448,7 +448,7 @@ func TestHandleMultipleQuitRequests(t *testing.T) {
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))

 	opts := &Options{
-		ListenAddress:   port,
+		ListenAddresses: []string{port},
 		MaxConnections:  512,
 		EnableLifecycle: true,
 		RoutePrefix:     "/",
@ -461,9 +461,9 @@ func TestHandleMultipleQuitRequests(t *testing.T) {
 	webHandler := New(nil, opts)
 	webHandler.config = &config.Config{}
 	webHandler.notifier = &notifier.Manager{}
-	l, err := webHandler.Listener()
+	l, err := webHandler.Listeners()
 	if err != nil {
-		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+		panic(fmt.Sprintf("Unable to start web listeners: %s", err))
 	}
 	ctx, cancel := context.WithCancel(context.Background())
 	closed := make(chan struct{})
@ -513,7 +513,7 @@ func TestAgentAPIEndPoints(t *testing.T) {
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))

 	opts := &Options{
-		ListenAddress:  port,
+		ListenAddresses: []string{port},
 		ReadTimeout:     30 * time.Second,
 		MaxConnections:  512,
 		Context:         nil,
@ -540,9 +540,9 @@ func TestAgentAPIEndPoints(t *testing.T) {
 	webHandler.SetReady(true)
 	webHandler.config = &config.Config{}
 	webHandler.notifier = &notifier.Manager{}
-	l, err := webHandler.Listener()
+	l, err := webHandler.Listeners()
 	if err != nil {
-		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+		panic(fmt.Sprintf("Unable to start web listeners: %s", err))
 	}

 	ctx, cancel := context.WithCancel(context.Background())
@ -628,3 +628,83 @@ func cleanupSnapshot(t *testing.T, dbDir string, resp *http.Response) {
 	require.NoError(t, os.Remove(filepath.Join(dbDir, "snapshots", snapshot.Data.Name)))
 	require.NoError(t, os.Remove(filepath.Join(dbDir, "snapshots")))
 }
+
+func TestMultipleListenAddresses(t *testing.T) {
+	t.Parallel()
+
+	dbDir := t.TempDir()
+
+	db, err := tsdb.Open(dbDir, nil, nil, nil, nil)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		require.NoError(t, db.Close())
+	})
+
+	// Create multiple ports for testing multiple ListenAddresses
+	port1 := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))
+	port2 := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))
+
+	opts := &Options{
+		ListenAddresses: []string{port1, port2},
+		ReadTimeout:     30 * time.Second,
+		MaxConnections:  512,
+		Context:         nil,
+		Storage:         nil,
+		LocalStorage:    &dbAdapter{db},
+		TSDBDir:         dbDir,
+		QueryEngine:     nil,
+		ScrapeManager:   &scrape.Manager{},
+		RuleManager:     &rules.Manager{},
+		Notifier:        nil,
+		RoutePrefix:     "/",
+		EnableAdminAPI:  true,
+		ExternalURL: &url.URL{
+			Scheme: "http",
+			Host:   "localhost" + port1,
+			Path:   "/",
+		},
+		Version:  &PrometheusVersion{},
+		Gatherer: prometheus.DefaultGatherer,
+	}
+
+	opts.Flags = map[string]string{}
+
+	webHandler := New(nil, opts)
+
+	webHandler.config = &config.Config{}
+	webHandler.notifier = &notifier.Manager{}
+	l, err := webHandler.Listeners()
+	if err != nil {
+		panic(fmt.Sprintf("Unable to start web listener: %s", err))
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	go func() {
+		err := webHandler.Run(ctx, l, "")
+		if err != nil {
+			panic(fmt.Sprintf("Can't start web handler:%s", err))
+		}
+	}()
+
+	// Give some time for the web goroutine to run since we need the server
+	// to be up before starting tests.
+	time.Sleep(5 * time.Second)
+
+	// Set to ready.
+	webHandler.SetReady(true)
+
+	for _, port := range []string{port1, port2} {
+		baseURL := "http://localhost" + port
+
+		resp, err := http.Get(baseURL + "/-/healthy")
+		require.NoError(t, err)
+		require.Equal(t, http.StatusOK, resp.StatusCode)
+		cleanupTestResponse(t, resp)
+
+		resp, err = http.Get(baseURL + "/-/ready")
+		require.NoError(t, err)
+		require.Equal(t, http.StatusOK, resp.StatusCode)
+		cleanupTestResponse(t, resp)
+	}
+}