proton-bridge: support /metrics and quiet scrape pipe noise

Author: mgarratt

images/proton-bridge/README.md

@@ -85,14 +85,14 @@ The container `HEALTHCHECK` script validates:
 - `gpg-agent` control socket responsiveness (`gpg-connect-agent /bye`)
 - listening state for SMTP/IMAP container ports
 - lightweight SMTP and IMAP banner-level handshake probes on local forwarded ports
-- metrics endpoint HTTP readiness (`/cgi-bin/metrics`)
+- metrics endpoint HTTP readiness (`/metrics`)
 
 ## Metrics
 
 The image now exposes Prometheus-formatted metrics from inside the container.
 
 - listen port: `${CONTAINER_METRICS_PORT}` (default `9154`)
-- scrape path: `/cgi-bin/metrics`
+- scrape path: `/metrics` (`/cgi-bin/metrics` also supported)
 
 Current metrics include:
 

images/proton-bridge/healthcheck.sh

@@ -13,6 +13,6 @@ netstat -ltn 2>/dev/null | grep -q "[.:]${CONTAINER_METRICS_PORT}[[:space:]]"
 
 printf 'QUIT\r\n' | nc -w 3 127.0.0.1 "${CONTAINER_SMTP_PORT}" | grep -Eq '^220 '
 printf 'a1 LOGOUT\r\n' | nc -w 3 127.0.0.1 "${CONTAINER_IMAP_PORT}" | grep -Eq '^\* (OK|PREAUTH|BYE) '
-printf 'GET /cgi-bin/metrics HTTP/1.0\r\nHost: localhost\r\n\r\n' \
-  | nc -w 3 127.0.0.1 "${CONTAINER_METRICS_PORT}" \
-  | grep -Eq '^HTTP/[0-9.]+ 200 '
+metrics_resp="$(printf 'GET /metrics HTTP/1.0\r\nHost: localhost\r\n\r\n' \
+  | nc -w 3 127.0.0.1 "${CONTAINER_METRICS_PORT}")"
+printf '%s\n' "${metrics_resp}" | grep -Eq '^HTTP/[0-9.]+ 200 '

images/proton-bridge/metrics/serve-http.sh

@@ -14,7 +14,7 @@ while IFS= read -r header; do
   esac
 done
 
-if [ "${method}" = "GET" ] && [ "${path}" = "/cgi-bin/metrics" ]; then
+if [ "${method}" = "GET" ] && { [ "${path}" = "/metrics" ] || [ "${path}" = "/cgi-bin/metrics" ]; }; then
   printf 'HTTP/1.1 200 OK\r\n'
   printf 'Content-Type: text/plain; version=0.0.4\r\n'
   printf 'Connection: close\r\n'