From 79ff76b3c0a4af47e365916035777eca5c046ad4 Mon Sep 17 00:00:00 2001
From: Lukasz Mierzwa <lukasz@cloudflare.com>
Date: Thu, 2 Jan 2025 12:23:19 +0000
Subject: [PATCH] Add /health endpoint for watch

---
 cmd/pint/watch.go |  4 ++++
 docs/changelog.md |  6 ++++++
 docs/index.md     | 15 ++++++++++-----
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/cmd/pint/watch.go b/cmd/pint/watch.go
index 2550cf6c..23e1181d 100644
--- a/cmd/pint/watch.go
+++ b/cmd/pint/watch.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/http"
 	_ "net/http/pprof"
@@ -180,6 +181,9 @@ func actionWatch(c *cli.Context, meta actionMeta, f pathFinderFunc) error {
 	rulesParsedTotal.WithLabelValues(config.RecordingRuleType).Add(0)
 	rulesParsedTotal.WithLabelValues(config.InvalidRuleType).Add(0)
 
+	http.HandleFunc("/health", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = io.WriteString(w, "OK\n")
+	})
 	http.Handle("/metrics", promhttp.HandlerFor(metricsRegistry, promhttp.HandlerOpts{
 		ErrorLog: slog.NewLogLogger(slog.Default().Handler(), slog.LevelError),
 		Timeout:  time.Second * 20,
diff --git a/docs/changelog.md b/docs/changelog.md
index 1c5f2eaa..33242812 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## v0.70.0
+
+### Added
+
+- When running `pint watch` command `/health` HTTP endpoint can now be used for liveness probes.
+
 ## v0.69.1
 
 ### Fixed
diff --git a/docs/index.md b/docs/index.md
index aae1bf45..62c4038c 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -152,6 +152,15 @@ Run pint as a daemon in watch mode where it continuously checks
 all rules found in selected files and exposes metrics about
 found problems.
 
+By default it will start a HTTP server on port `8080` and run all checks every
+10 minutes. This can be customised by passing extra flags to the `watch` command.
+Run `pint watch -h` to see all available flags.
+
+Currently supported HTTP paths:
+
+- `/health` - static endpoint for liveness probes.
+- `/metrics` - returns Prometheus metrics, see below.
+
 #### Manually selecting files and directories
 
 You can tell it to continuously test specific files or directories:
@@ -203,11 +212,7 @@ pint watch rule_files local
 
 #### Accessing watch mode metrics
 
-By default it will start a HTTP server on port `8080` and run all checks every
-10 minutes. This can be customised by passing extra flags to the `watch` command.
-Run `pint watch -h` to see all available flags.
-
-Query `/metrics` to see all expose metrics, example with default flags:
+Query `/metrics` HTTP endpoint to see all expose metrics, example with default flags:
 
 ```shell
 curl -s http://localhost:8080/metrics