nginx fails to start - troubleshoot - nginx

Question

I have a simple nginx config that is syntactically correct. I install nginx using chef and the chef script works fine.
But as I check status of nginx , I see it is in failed state. If I reload nginx , it again goes in failed state. journalctl -xn also doesnt give much of error except :
[root#localhost vagrant]# journalctl -xn
-- Logs begin at Wed 2016-10-26 04:28:18 UTC, end at Wed 2016-10-26 04:45:00 UTC. --
Oct 26 04:45:00 localhost.localdomain kill[17003]: -s, --signal <sig> send specified signal
Oct 26 04:45:00 localhost.localdomain kill[17003]: -q, --queue <sig> use sigqueue(2) rather than kill(2)
Oct 26 04:45:00 localhost.localdomain kill[17003]: -p, --pid print pids without signaling them
Oct 26 04:45:00 localhost.localdomain kill[17003]: -l, --list [=<signal>] list signal names, or convert one to a name
Oct 26 04:45:00 localhost.localdomain kill[17003]: -L, --table list signal names and numbers
Oct 26 04:45:00 localhost.localdomain kill[17003]: -h, --help display this help and exit
Oct 26 04:45:00 localhost.localdomain kill[17003]: -V, --version output version information and exit
Oct 26 04:45:00 localhost.localdomain kill[17003]: For more details see kill(1).
Oct 26 04:45:00 localhost.localdomain systemd[1]: nginx.service: control process exited, code=exited status=1
Oct 26 04:45:00 localhost.localdomain systemd[1]: Unit nginx.service entered failed state.
[root#localhost vagrant]#
nginx -t is successful and I see nothing in /var/log/nginx/errors.log
Is there any other way to troubleshoot exactly why this fails ?
Both systemctl status nginx.service gives:
[root#localhost vagrant]# systemctl status nginx.service
nginx.service - The nginx HTTP and reverse proxy server
Loaded: loaded (/usr/lib/systemd/system/nginx.service; static)
Active: failed (Result: exit-code) since Wed 2016-10-26 04:45:00 UTC; 9h ago
Process: 17003 ExecStop=/bin/kill -s QUIT $MAINPID (code=exited, status=1/FAILURE)
Process: 16999 ExecStart=/opt/nginx-1.10.1/sbin/nginx (code=exited, status=0/SUCCESS)
Process: 16998 ExecStartPre=/opt/nginx-1.10.1/sbin/nginx -t (code=exited, status=0/SUCCESS)
Main PID: 16999 (code=exited, status=0/SUCCESS)
Oct 26 04:45:00 localhost.localdomain kill[17003]: -s, --signal <sig> send specified signal
Oct 26 04:45:00 localhost.localdomain kill[17003]: -q, --queue <sig> use sigqueue(2) rather than kill(2)
Oct 26 04:45:00 localhost.localdomain kill[17003]: -p, --pid print pids without signaling them
Oct 26 04:45:00 localhost.localdomain kill[17003]: -l, --list [=<signal>] list signal names, or convert one to a name
Oct 26 04:45:00 localhost.localdomain kill[17003]: -L, --table list signal names and numbers
Oct 26 04:45:00 localhost.localdomain kill[17003]: -h, --help display this help and exit
Oct 26 04:45:00 localhost.localdomain kill[17003]: -V, --version output version information and exit
Oct 26 04:45:00 localhost.localdomain kill[17003]: For more details see kill(1).
Oct 26 04:45:00 localhost.localdomain systemd[1]: nginx.service: control process exited, code=exited status=1
Oct 26 04:45:00 localhost.localdomain systemd[1]: Unit nginx.service entered failed state.
systemctl cat nginx.service gives :
[root#virsinplatformapi02 sysadmin]# systemctl cat nginx.service
Unknown operation 'cat'.
I cd cd /lib/systemd/system and do cat on nginx.service:
[root#virsinplatformapi02 system]# cat nginx.service
[Unit]
Description=The nginx HTTP and reverse proxy server
After=network.target remote-fs.target nss-lookup.target
[Service]
ExecStartPre=/opt/nginx-1.10.1/sbin/nginx -t
ExecStart=/opt/nginx-1.10.1/sbin/nginx
ExecReload=/bin/kill -s HUP $MAINPID
ExecStop=/bin/kill -s QUIT $MAINPID
PrivateTmp=true
[Install]
If I do a echo $MAINPID , I get nothing.

Answer 1

That is not very good unitfile. Type is not set and defaults to simple, while you want to you forking for nginx. That may be the reason for the wrong $MAINPID value. Try to use official unit:
[Unit]
Description=The NGINX HTTP and reverse proxy server
After=syslog.target network.target remote-fs.target nss-lookup.target
[Service]
Type=forking
PIDFile=/run/nginx.pid
ExecStartPre=/opt/nginx-1.10.1/sbin/nginx -t
ExecStart=/opt/nginx-1.10.1/sbin/nginx
ExecReload=/bin/kill -s HUP $MAINPID
ExecStop=/bin/kill -s QUIT $MAINPID
PrivateTmp=true
[Install]
WantedBy=multi-user.target
You should just add it to /etc/systemd/system/nginx.service - that directory it intended for administrator-created units, and has priority.