prometheus: serve 9274 via nginx instead of ncat (#85)

rootfs/etc/s6-overlay/s6-rc.d/prometheus-readsb/run

@@ -1,2 +0,0 @@
-#!/bin/sh
-exec /etc/s6-overlay/scripts/prometheus-readsb

rootfs/etc/s6-overlay/s6-rc.d/prometheus-readsb/type

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

rootfs/etc/s6-overlay/scripts/prometheus-readsb

@@ -1,32 +0,0 @@
-#!/command/with-contenv bash
-# shellcheck shell=bash disable=SC1091
-
-source /scripts/common
-
-#---------------------------------------------------------------------------------------------
-# Copyright (C) 2023-2024, Ramon F. Kolb (kx1t) and contributors
-#
-# This program is free software: you can redistribute it and/or modify it
-# under the terms of the GNU General Public License as published by the
-# Free Software Foundation, either version 3 of the License, or (at your option)
-# any later version.
-#
-# This program is distributed in the hope that it will be useful, but
-# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along with this program.
-# If not, see <https://www.gnu.org/licenses/>.
-#---------------------------------------------------------------------------------------------
-
-if chk_enabled "$PROMETHEUS_ENABLE"; then
-    while [[ ! -f /run/readsb-prometheus.prom ]]
-    do
-        sleep 1
-    done
-    trap "pkill -P $$ || true; s6wrap --timestamps --prepend=prometheus-readsb --quiet --args echo 'service stopping'; exit 0" SIGTERM SIGINT SIGHUP SIGQUIT
-    echo -e "HTTP/1.1 200 OK\nContent-Type: text/plain\n\n$(cat /run/readsb-prometheus.prom)" | ncat -l "${PROMETHEUSPORT:-9274}" > /dev/null 2>&1 &
-    wait
-else
-    exec sleep infinity
-fi

rootfs/etc/s6-overlay/startup.d/99-prometheus-conf

@@ -0,0 +1,24 @@
+#!/command/with-contenv bash
+
+source /scripts/common
+
+if ! chk_enabled "$PROMETHEUS_ENABLE"; then
+    exit 0
+fi
+
+# serve port 9274 always replying with stats.prom regardless of requested path
+
+cat > /etc/nginx/sites-enabled/prometheus_9274 <<EOF
+server {
+    listen 9274 default_server;
+    root /var/www/html;
+    server_name _;
+    location /metrics {
+        alias /run/readsb/stats.prom;
+    }
+    location / {
+        alias /run/readsb/stats.prom;
+        rewrite (.*) /metrics last;
+    }
+}
+EOF