Add SC4S_DEBUG_CONTAINER to prevent container exit on startup error

docs/troubleshooting.md

@@ -92,6 +92,8 @@ and navigate to `/opt/syslog-ng/etc/` to see the actual config files in use.  If
 itself, you can also modify files directly and reload syslog-ng with the command `kill -1 1` in the container.  This is an advanced topic
 and futher help can be obtained via the github issue tracker and Slack channels.
 
+When debugging a configuration syntax issue at startup the container must remain running. This can be enabled by adding `SC4S_DEBUG_CONTAINER=yes` to the `env_file`
+
 ## Run the container with a null entrypoint (Advanced!)
 
 You can run the container without the usual entrypoint shell script by executing this command (modified to suit your environment):

package/sbin/entrypoint.sh

@@ -60,7 +60,13 @@ sleep 5
 if ! ps -p $pid > /dev/null
 then
    echo "syslog-ng failed to start $pid is not running"
-   exit $(wait ${pid})
+   /opt/syslog-ng/sbin/syslog-ng -s
+   if [ "${SC4S_DEBUG_CONTAINER}" == "yes" ]
+   then
+    exit $(wait ${pid})
+  else
+    tail -f /dev/null
+  fi
    # Do something knowing the pid exists, i.e. the process with $PID is running
 fi