From 80f966b80c1c4a0e385a46bbfef56454fbf9af32 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Thu, 13 Jan 2022 22:53:40 +0200
Subject: [PATCH] app/vmalert: add `stripPort` template function in the same
 way as Prometheus does

See https://github.com/prometheus/prometheus/pull/10002
---
 app/vmalert/notifier/template_func.go | 11 +++++++++++
 docs/CHANGELOG.md                     |  1 +
 2 files changed, 12 insertions(+)

diff --git a/app/vmalert/notifier/template_func.go b/app/vmalert/notifier/template_func.go
index 9704f17c2..2732895b7 100644
--- a/app/vmalert/notifier/template_func.go
+++ b/app/vmalert/notifier/template_func.go
@@ -17,6 +17,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"net"
 	"net/url"
 	"regexp"
 	"strings"
@@ -61,6 +62,7 @@ var tmplFunc textTpl.FuncMap
 
 // InitTemplateFunc initiates template helper functions
 func InitTemplateFunc(externalURL *url.URL) {
+	// See https://prometheus.io/docs/prometheus/latest/configuration/template_reference/
 	tmplFunc = textTpl.FuncMap{
 		/* Strings */
 
@@ -91,6 +93,15 @@ func InitTemplateFunc(externalURL *url.URL) {
 		// alias for https://golang.org/pkg/strings/#ToLower
 		"toLower": strings.ToLower,
 
+		// stripPort splits string into host and port, then returns only host.
+		"stripPort": func(hostPort string) string {
+			host, _, err := net.SplitHostPort(hostPort)
+			if err != nil {
+				return hostPort
+			}
+			return host
+		},
+
 		/* Numbers */
 
 		// humanize converts given number to a human readable format
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 605b2b4b8..4010882a1 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -22,6 +22,7 @@ scrape_configs:
 * FEATURE: [vmrestore](https://docs.victoriametrics.com/vmrestore.html): store `restore-in-progress` file in `-dst` directory while `vmrestore` is running. This file is automatically deleted when `vmrestore` is successfully finished. This helps detecting incompletely restored data on VictoriaMetrics start. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1958).
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl.html): print the last sample timestamp when the data migration is interrupted either by user or by error. This helps continuing the data migration from the interruption moment. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1236).
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert.html): expose `vmalert_remotewrite_total` metric at `/metrics` page. This makes possible calculating SLOs for error rate during writing recording rules and alert state to `-remoteWrite.url` with the query `vmalert_remotewrite_errors_total / vmalert_remotewrite_total`. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2040). Thanks to @afoninsky .
+* FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert.html): add `stripPort` template function in the same way as [Prometheus does](https://github.com/prometheus/prometheus/pull/10002).
 
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): make sure that `vmagent` replicas scrape the same targets at different time offsets when [replication is enabled in vmagent clustering mode](https://docs.victoriametrics.com/vmagent.html#scraping-big-number-of-targets). This guarantees that the [deduplication](https://docs.victoriametrics.com/#deduplication) consistently leaves samples from the same `vmagent` replica.
 * BUGFIX: return the proper response stub from `/api/v1/query_exemplars` handler, which is needed for Grafana v8+. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1999).