Can you provide the content of /var/log/nginx/error.log (last 20-30 lines)? There should be something about Passenger.
From /var/log/nginx/error.log after a service nginx restart
[ 2016-10-13 12:43:14.9445 28428/7fa2fe700700 age/Cor/CoreMain.cpp:532 ]: Signal received. Gracefully shutting down... (send signal 2 more time(s) to force shutdown)
[ 2016-10-13 12:43:14.9445 28433/7f04b7fff700 age/Ust/UstRouterMain.cpp:422 ]: Signal received. Gracefully shutting down... (send signal 2 more time(s) to force shutdown)
[ 2016-10-13 12:43:14.9446 28433/7f04bc4d77e0 age/Ust/UstRouterMain.cpp:492 ]: Received command to shutdown gracefully. Waiting until all clients have disconnected...
[ 2016-10-13 12:43:14.9446 28428/7fa2ff2ac7e0 age/Cor/CoreMain.cpp:901 ]: Received command to shutdown gracefully. Waiting until all clients have disconnected...
[ 2016-10-13 12:43:14.9447 28433/7f04b75fe700 Ser/Server.h:817 ]: [UstRouterApiServer] Freed 0 spare client objects
[ 2016-10-13 12:43:14.9447 28433/7f04b75fe700 Ser/Server.h:464 ]: [UstRouterApiServer] Shutdown finished
[ 2016-10-13 12:43:14.9449 28428/7fa2fd1fc700 Ser/Server.h:817 ]: [ServerThr.3] Freed 128 spare client objects
[ 2016-10-13 12:43:14.9449 28428/7fa2fdc7e700 Ser/Server.h:817 ]: [ServerThr.2] Freed 128 spare client objects
[ 2016-10-13 12:43:14.9449 28428/7fa2fdc7e700 Ser/Server.h:464 ]: [ServerThr.2] Shutdown finished
[ 2016-10-13 12:43:14.9449 28428/7fa2fd1fc700 Ser/Server.h:464 ]: [ServerThr.3] Shutdown finished
[ 2016-10-13 12:43:14.9449 28428/7fa2d7fff700 Ser/Server.h:817 ]: [ServerThr.4] Freed 128 spare client objects
[ 2016-10-13 12:43:14.9449 28433/7f04b7fff700 Ser/Server.h:464 ]: [UstRouter] Shutdown finished
[ 2016-10-13 12:43:14.9449 28428/7fa2d7fff700 Ser/Server.h:464 ]: [ServerThr.4] Shutdown finished
[ 2016-10-13 12:43:14.9450 28428/7fa2fe700700 Ser/Server.h:817 ]: [ServerThr.1] Freed 128 spare client objects
[ 2016-10-13 12:43:14.9450 28428/7fa2fe700700 Ser/Server.h:464 ]: [ServerThr.1] Shutdown finished
[ 2016-10-13 12:43:14.9451 28428/7fa2d75fe700 Ser/Server.h:817 ]: [ApiServer] Freed 0 spare client objects
[ 2016-10-13 12:43:14.9451 28428/7fa2d75fe700 Ser/Server.h:464 ]: [ApiServer] Shutdown finished
[ 2016-10-13 12:43:14.9454 28433/7f04bc4d77e0 age/Ust/UstRouterMain.cpp:523 ]: Passenger UstRouter shutdown finished
[ 2016-10-13 12:43:15.0139 28428/7fa2ff2ac7e0 age/Cor/CoreMain.cpp:967 ]: Passenger core shutdown finished
[ 2016-10-13 12:43:15.1536 10311/7f6df34b67e0 age/Wat/WatchdogMain.cpp:1291 ]: Starting Passenger watchdog...
[ 2016-10-13 12:43:15.1595 10314/7f37696f37e0 age/Cor/CoreMain.cpp:982 ]: Starting Passenger core...
[ 2016-10-13 12:43:15.1596 10314/7f37696f37e0 age/Cor/CoreMain.cpp:235 ]: Passenger core running in multi-application mode.
[ 2016-10-13 12:43:15.1620 10314/7f37696f37e0 age/Cor/CoreMain.cpp:732 ]: Passenger core online, PID 10314
[ 2016-10-13 12:43:15.1650 10321/7f2b0ffec7e0 age/Ust/UstRouterMain.cpp:529 ]: Starting Passenger UstRouter...
[ 2016-10-13 12:43:15.1660 10321/7f2b0ffec7e0 age/Ust/UstRouterMain.cpp:342 ]: Passenger UstRouter online, PID 10321
Tried with the hello world app as well, I thought that this my customers app might be an issue so I had thought that I would use this as the test app... same result.
Here are the logs from httpd/error.log after a service httpd restart and attempt to load the app.
[Thu Oct 13 12:51:25 2016] [notice] caught SIGTERM, shutting down
[Thu Oct 13 12:51:28 2016] [notice] SELinux policy enabled; httpd running as context unconfined_u:system_r:httpd_t:s0
[Thu Oct 13 12:51:28 2016] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Thu Oct 13 12:51:28 2016] [warn] No JkLogFile defined in httpd.conf. Using default /etc/httpd/logs/mod_jk.log
[Thu Oct 13 12:51:28 2016] [warn] No JkShmFile defined in httpd.conf. Using default /etc/httpd/logs/jk-runtime-status
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] Init: Name-based SSL virtual hosts only work for clients with TLS server name indication support (RFC 4366)
[Thu Oct 13 12:51:28 2016] [notice] Digest: generating secret for digest authentication ...
[Thu Oct 13 12:51:28 2016] [notice] Digest: done
[Thu Oct 13 12:51:28 2016] [notice] mod_bw : Memory Allocated 0 bytes (each conf takes 48 bytes)
[Thu Oct 13 12:51:28 2016] [notice] mod_bw : Version 0.92 - Initialized [0 Confs]
[Thu Oct 13 12:51:28 2016] [warn] No JkLogFile defined in httpd.conf. Using default /etc/httpd/logs/mod_jk.log
[Thu Oct 13 12:51:28 2016] [warn] No JkShmFile defined in httpd.conf. Using default /etc/httpd/logs/jk-runtime-status
[Thu Oct 13 12:51:28 2016] [error] python_init: Python version mismatch, expected '2.6.5', found '2.6.6'.
[Thu Oct 13 12:51:28 2016] [error] python_init: Python executable found '/usr/bin/python'.
[Thu Oct 13 12:51:28 2016] [error] python_init: Python path being used '/usr/lib64/python26.zip:/usr/lib64/python2.6/:/usr/lib64/python2.6/plat-linux2:/usr/lib64/python2.6/lib-tk:/usr/lib64/python2.6/lib-old:/usr/lib64/python2.6/lib-dynload'.
[Thu Oct 13 12:51:28 2016] [notice] mod_python: Creating 4 session mutexes based on 256 max processes and 0 max threads.
[Thu Oct 13 12:51:28 2016] [notice] mod_python: using mutex_directory /tmp
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] RSA server certificate CommonName (CN) `Plesk' does NOT match server name!?
[Thu Oct 13 12:51:28 2016] [warn] Init: Name-based SSL virtual hosts only work for clients with TLS server name indication support (RFC 4366)
[Thu Oct 13 12:51:28 2016] [notice] Apache/2.2.15 (Unix) DAV/2 mod_fcgid/2.3.9 mod_jk/1.2.40 Phusion_Passenger/5.0.30 PHP/5.4.45 mod_python/3.3.1 Python/2.6.6 mod_ssl/2.2.15 OpenSSL/1.0.1e-fips mod_perl/2.0.4 Perl/v5.10.1 configured -- resuming normal operations
again tried the hello world app and still same result :-(
Update: The Hello World app works fine when called like this:
root@lightning my-app]# /opt/plesk/node/4/bin/node ./app.js
And when the listening port is changed from 0 to 8080 (firewall opened on 8080 also)