feat(anubis): add /healthz route to metrics server (#843)

* feat(anubis): add /healthz route to metrics server

Also add health check test for Docker Compose and update documentation
for health checking Anubis with Docker Compose.

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

test/git-clone/docker-compose.yaml

@@ -12,11 +12,11 @@ services:
   anubis:
     image: ko.local/anubis
     environment:
-      BIND: ":3000"
+      BIND: ":8005"
       TARGET: http://cgit:80
       USE_REMOTE_ADDRESS: "true"
     ports:
-      - 3000:3000
+      - 8005:8005
 
 volumes:
   cgit-data:

test/git-clone/test.sh

@@ -21,6 +21,6 @@ docker compose up -d
 
 sleep 2
 
-(cd ./var/clones && git clone http://localhost:3000/status.git)
+(cd ./var/clones && git clone http://localhost:8005/status.git)
 
 docker compose down

test/healthcheck/docker-compose.yaml

@@ -0,0 +1,15 @@
+services:
+  web:
+    image: ghcr.io/xe/nginx-micro:v1.29.0
+
+  anubis:
+    image: ko.local/anubis
+    environment:
+      TARGET: http://web:80
+      USE_REMOTE_ADDRESS: "true"
+    healthcheck:
+      test: ["CMD", "anubis", "--healthcheck"]
+      interval: 5s
+      timeout: 30s
+      retries: 5
+      start_period: 500ms

test/healthcheck/test.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+set -eo pipefail
+
+export VERSION=$GITHUB_COMMIT-test
+export KO_DOCKER_REPO=ko.local
+
+set -u
+
+(
+  cd ../.. && \
+  ko build --platform=all --base-import-paths --tags="latest" --image-user=1000 --image-annotation="" --image-label="" ./cmd/anubis -L
+)
+
+docker compose up -d
+
+attempt=1
+max_attempts=5
+delay=2
+
+while ! docker compose ps | grep healthy; do
+  if (( attempt >= max_attempts )); then
+    echo "Service did not become healthy after $max_attempts attempts."
+    exit 1
+  fi
+  echo "Waiting for healthy service... attempt $attempt"
+  sleep $delay
+  delay=$(( delay * 2 ))
+  attempt=$(( attempt + 1 ))
+done
+
+docker compose down

test/healthcheck/var/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore