send prometheus logs to syslog

Reviewed-on: Sutty/containers-monit#1

.woodpecker.yml

@@ -30,3 +30,6 @@ matrix:
   - ALPINE_VERSION: 3.15.4
     RUBY_VERSION: 3.0
     RUBY_PATCH: 4
+  - ALPINE_VERSION: 3.16.0
+    RUBY_VERSION: 3.1
+    RUBY_PATCH: 2

Procfile

@@ -5,4 +5,4 @@ blazer_5m: bundle exec rake blazer:run_checks SCHEDULE="5 minutes"
 blazer_1h: bundle exec rake blazer:run_checks SCHEDULE="1 hour"
 blazer_1d: bundle exec rake blazer:run_checks SCHEDULE="1 day"
 blazer: bundle exec rake blazer:send_failing_checks
-prometheus: bundle exec prometheus_exporter -b 0.0.0.0 --prefix "lunar_"
+prometheus: bundle exec prometheus_exporter -b ::

entrypoint.sh

@@ -18,17 +18,17 @@ case $1 in
 
     ;;
   prometheus)
-    rm -f /tmp/prometheus.pid
-
     daemonize -c /srv \
               -p /tmp/prometheus.pid \
               -l /tmp/prometheus.pid \
               -u rails \
+              /usr/local/bin/syslogize \
               /usr/bin/foreman start -f /etc/Procfile -d /srv prometheus
     ;;
 
   prometheus-stop)
-    cat /tmp/prometheus.pid | xargs -r kill
+    test ! -f /tmp/prometheus.pid || cat /tmp/prometheus.pid | xargs -r kill
+    rm -f /tmp/prometheus.pid
 
     ;;
 

syslogize.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+# A wrapper for programs that can't write to syslog.  Output and error
+# are sent to syslog.
+#
+# Use LOGGER environment variable to pass options to `logger`.  They'll
+# probably be system-dependent, so handle with care.
+#
+# Usage:
+#
+# LOGGER="-t program" syslogize program -o -p --tions argu ments
+#
+# daemonize /usr/local/bin/syslogize program
+
+if test $# -eq 0 ; then
+  grep "^#" $0 | grep -v /bin/sh | sed -re "s/^#\s*//" >&2
+
+  exit 1
+fi
+
+LOGGER="${LOGGER:--t $1}"
+
+propagate_signal () {
+  logger ${LOGGER} "Received $1 signal"
+  jobs -p | xargs kill -$1 
+}
+
+for signal in HUP INT QUIT USR1 USR2 TERM; do
+  trap "propagate_signal ${signal}" ${signal}
+done
+
+$@ 2>&1 | logger ${LOGGER} &
+
+wait $!