Replace Docker healthcheck with s6 readiness notifications

Docker's healthcheck polling was used to determine when services were ready. s6-notifyoncheck provides the same readiness detection but integrates natively with the s6 supervision tree, enabling proper dependency ordering between services (e.g. buildkitd waits for dnsmasq and haproxy) without external polling.

Author: dash14

compose.yml

@@ -33,9 +33,3 @@ services:
       - ALLOWED_IP_RULES=${ALLOWED_IP_RULES:-}
       - EXTERNAL_RESOLVER=${EXTERNAL_RESOLVER:-1.1.1.1,8.8.8.8}
     restart: unless-stopped
-    healthcheck:
-      test: ["CMD", "sh", "-c", "curl -sf --unix-socket /var/run/haproxy-health.sock http://localhost/health"]
-      interval: 30s
-      timeout: 5s
-      retries: 10
-      start_period: 5s

docker/Dockerfile

@@ -68,10 +68,5 @@ COPY files/THIRD_PARTY_LICENSES /opt/buildcage/THIRD_PARTY_LICENSES
 # s6 service definitions and init scripts
 COPY files/s6-rc.d/ /etc/s6-overlay/s6-rc.d/
 COPY files/s6-scripts/ /etc/s6-overlay/scripts/
-RUN chmod +x /etc/s6-overlay/scripts/* && \
-    chmod +x /etc/s6-overlay/s6-rc.d/dnsmasq/run && \
-    chmod +x /etc/s6-overlay/s6-rc.d/haproxy/run && \
-    chmod +x /etc/s6-overlay/s6-rc.d/haproxy-log/run
 
 ENTRYPOINT ["/init"]
-CMD ["buildkitd", "--oci-worker-net=cni"]

docker/files/s6-rc.d/buildkitd/dependencies.d/dnsmasq

@@ -0,0 +1,2 @@
+#!/command/with-contenv sh
+exec buildkitd --oci-worker-net=cni

docker/files/s6-rc.d/buildkitd/dependencies.d/haproxy

@@ -0,0 +1 @@
+longrun

docker/files/s6-rc.d/buildkitd/dependencies.d/init-iptables

@@ -0,0 +1,2 @@
+#!/bin/sh
+nslookup localhost 127.0.0.1 > /dev/null 2>&1

docker/files/s6-rc.d/buildkitd/run

@@ -0,0 +1 @@
+3

docker/files/s6-rc.d/buildkitd/type

@@ -1,2 +1,2 @@
 #!/command/with-contenv sh
-exec dnsmasq --conf-file=/etc/dnsmasq.conf -k
+exec s6-notifyoncheck -d -w 250 -n 12 dnsmasq --conf-file=/etc/dnsmasq.conf -k