app/vlselect: introduce -vmalert.proxyURL flag to proxy /api/v1/notifiers, /api/v1/alerts and /api/v1/rules requests to VMAlert

app/vlselect/main.go

@@ -6,6 +6,8 @@ import (
 	"flag"
 	"fmt"
 	"net/http"
+	nethttputil "net/http/httputil"
+	"net/url"
 	"strings"
 	"time"
 
@@ -28,6 +30,8 @@ var (
 
 	disableSelect   = flag.Bool("select.disable", false, "Whether to disable /select/* HTTP endpoints")
 	disableInternal = flag.Bool("internalselect.disable", false, "Whether to disable /internal/select/* HTTP endpoints")
+
+	vmalertProxyURL = flag.String("vmalert.proxyURL", "", "Optional URL for proxying requests to vmalert")
 )
 
 func getDefaultMaxConcurrentRequests() int {
@@ -47,6 +51,7 @@ func getDefaultMaxConcurrentRequests() int {
 // Init initializes vlselect
 func Init() {
 	concurrencyLimitCh = make(chan struct{}, *maxConcurrentRequests)
+	initVMAlertProxy()
 }
 
 // Stop stops vlselect
@@ -267,6 +272,36 @@ func processSelectRequest(ctx context.Context, w http.ResponseWriter, r *http.Re
 		logsql.ProcessStreamsRequest(ctx, w, r)
 		logsqlStreamsDuration.UpdateDuration(startTime)
 		return true
+	case "/select/api/v1/notifiers":
+		notifiersRequests.Inc()
+		if len(*vmalertProxyURL) > 0 {
+			r.URL.Path = path[len("/select"):]
+			proxyVMAlertRequests(w, r)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, `{"status":"success","data":{"notifiers":[]}}`)
+		return true
+	case "/select/api/v1/alerts":
+		alertsRequests.Inc()
+		if len(*vmalertProxyURL) > 0 {
+			r.URL.Path = path[len("/select"):]
+			proxyVMAlertRequests(w, r)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, `{"status":"success","data":{"alerts":[]}}`)
+		return true
+	case "/select/api/v1/rules":
+		rulesRequests.Inc()
+		if len(*vmalertProxyURL) > 0 {
+			r.URL.Path = path[len("/select"):]
+			proxyVMAlertRequests(w, r)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, `{"status":"success","data":{"rules":[]}}`)
+		return true
 	default:
 		return false
 	}
@@ -285,6 +320,39 @@ func getMaxQueryDuration(r *http.Request) time.Duration {
 	return d
 }
 
+func proxyVMAlertRequests(w http.ResponseWriter, r *http.Request) {
+	defer func() {
+		err := recover()
+		if err == nil || err == http.ErrAbortHandler {
+			// Suppress http.ErrAbortHandler panic.
+			// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1353
+			return
+		}
+		// Forward other panics to the caller.
+		panic(err)
+	}()
+	r.Host = vmalertProxyHost
+	vmalertProxy.ServeHTTP(w, r)
+}
+
+// initVMAlertProxy must be called after flag.Parse(), since it uses command-line flags.
+func initVMAlertProxy() {
+	if len(*vmalertProxyURL) == 0 {
+		return
+	}
+	proxyURL, err := url.Parse(*vmalertProxyURL)
+	if err != nil {
+		logger.Fatalf("cannot parse -vmalert.proxyURL=%q: %s", *vmalertProxyURL, err)
+	}
+	vmalertProxyHost = proxyURL.Host
+	vmalertProxy = nethttputil.NewSingleHostReverseProxy(proxyURL)
+}
+
+var (
+	vmalertProxyHost string
+	vmalertProxy     *nethttputil.ReverseProxy
+)
+
 var (
 	logsqlFacetsRequests = metrics.NewCounter(`vl_http_requests_total{path="/select/logsql/facets"}`)
 	logsqlFacetsDuration = metrics.NewSummary(`vl_http_request_duration_seconds{path="/select/logsql/facets"}`)
@@ -321,4 +389,8 @@ var (
 
 	// no need to track duration for tail requests, as they usually take long time
 	logsqlTailRequests = metrics.NewCounter(`vl_http_requests_total{path="/select/logsql/tail"}`)
+
+	rulesRequests     = metrics.NewCounter(`vl_http_requests_total{path="/select/api/v1/rules"}`)
+	alertsRequests    = metrics.NewCounter(`vl_http_requests_total{path="/select/api/v1/alerts"}`)
+	notifiersRequests = metrics.NewCounter(`vl_http_requests_total{path="/select/api/v1/notifiers"}`)
 )

docs/victorialogs/CHANGELOG.md

@@ -18,6 +18,8 @@ according to [these docs](https://docs.victoriametrics.com/victorialogs/quicksta
 
 ## tip
 
+* FEATURE: proxy requests to `/api/v1/notifiers`, `/api/v1/alerts` and `/api/v1/rules` to VMAlert, when `-vmalert.proxyURL` flag is set. See [#8272](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/8272).
+
 ## [v1.24.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.24.0-victorialogs)
 
 Released at 2025-06-20

docs/victorialogs/README.md

@@ -261,6 +261,16 @@ rsync -avh --progress --delete <username>@<host>:<path-to-victorialogs-backup> <
 It is also possible to use **the disk snapshot** in order to perform a backup. This feature could be provided by your operating system,
 cloud provider, or third-party tools. Note that the snapshot must be **consistent** to ensure reliable backup.
 
+## vmalert
+
+VictoriaLogs is capable of proxying requests to [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/)
+when `-vmalert.proxyURL` flag is set. Use this feature for the following cases:
+* for proxying requests from [Grafana Alerting UI](https://grafana.com/docs/grafana/latest/alerting/);
+* for accessing vmalerts UI through VictoriaLogs Web interface.
+
+For accessing vmalerts UI through VictoriaLogs configure `-vmalert.proxyURL` flag and visit
+`http://<victorialogs-addr>:9428/vmalert/` link.
+
 ## Multitenancy
 
 VictoriaLogs supports multitenancy. A tenant is identified by `(AccountID, ProjectID)` pair, where `AccountID` and `ProjectID` are arbitrary 32-bit unsigned integers.
@@ -723,6 +733,8 @@ Pass `-help` to VictoriaLogs in order to see the list of supported command-line
     	Optional minimum TLS version to use for the corresponding -httpListenAddr if -tls is set. Supported values: TLS10, TLS11, TLS12, TLS13
     	Supports an array of values separated by comma or specified via multiple flags.
     	Value can contain comma inside single-quoted or double-quoted string, {}, [] and () braces.
+  -vmalert.proxyURL string
+        Optional URL for proxying requests to vmalert. For example, if -vmalert.proxyURL=http://vmalert:8880 , then alerting API requests such as /api/v1/rules from Grafana will be proxied to http://vmalert:8880/api/v1/rules
   -version
     	Show VictoriaMetrics version
 ```