Nginx smooth upgrade detailed operation method

1. Smooth upgrade overview
Nginx conveniently helps us with smooth upgrades. The principle is as follows:
(1) start a new process while dropping the old one.
(2) the old process is responsible for processing requests that are still pending, but it no longer accepts processing requests.
(3) the new process accepts the new request.
(4) after the old process has processed all requests and closed all connections, it stops.
This is very convenient to achieve a smooth upgrade. There are generally two situations where you need to upgrade Nginx, one is when you do upgrade Nginx, and the other is when you add a new module to Nginx.
2. The upgrade process
The specific operation is also very simple, as follows:

(0) view the current version
In the directory where the Nginx executable is stored, type:

./nginx -V  

(1) download the new Nginx version and compile it.

wget nginx-1.0.11.tar.gz  
tar zxvf nginx-1.0.11.tar.gz  
cd nginx-1.0.11  
./configure --add-module=/customized_module_0 --add-module=/customized_module_1  
make  

Be careful not to proceed with make install

(2) back up the old version of the executable

cd /usr/local/nginx/sbin  
sudo cp nginx nginx.old  

(3) modify the configuration file
Make configuration file changes if necessary.

(4) copy the new executable

sudo cp /home/michael/tmp/nginx-1.0.11/objs/nginx /usr/local/nginx/sbin/  

(5) upgrade

cd /home/michael/tmp/nginx-1.0.11  
make upgrade  

(6) clean up redundant files

rm -rf /home/michael/tmp/nginx-1.0.11  

(7) view the Nginx version

cd /usr/local/nginx/sbin  
./nginx -V  

3. Observe the process change

It can be observed on my machine that I configured 10 worker processes, and observed after starting:

root      6241 10419  0 10:51 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx  
nobody    6242  6241  2 10:51 ?        00:00:00 nginx: worker process        
nobody    6243  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6244  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6245  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6246  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6247  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6248  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6249  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6250  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6251  6241  1 10:51 ?        00:00:00 nginx: worker process        
nobody    6252  6241  0 10:51 ?        00:00:00 nginx: cache manager process  
nobody    6253  6241  0 10:51 ?        00:00:00 nginx: cache loader process  
luming    6310 25051  0 10:51 pts/1    00:00:00 grep --color=auto nginx  
nobody    7995 10419  0 Jan12 ?        00:20:37 nginx: worker process is shutting down  
nobody    7996 10419  0 Jan12 ?        00:20:11 nginx: worker process is shutting down  
nobody    7998 10419  0 Jan12 ?        00:20:04 nginx: worker process is shutting down  
nobody    8003 10419  0 Jan12 ?        00:20:12 nginx: worker process is shutting down  
root     10419     1  0 Jan08 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx  

You can see that the new process has 1 master and 10 worker, plus 1 old master (which can be seen from the time) and 4 worker (the other 6 old worker have already processed all the connections and shutdown has). There is also an loader process. In a few seconds you'll see that worker has only two:

root      6241 10419  0 10:51 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx  
nobody    6242  6241  1 10:51 ?        00:00:00 nginx: worker process        
nobody    6243  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6244  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6245  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6246  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6247  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6248  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6249  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6250  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6251  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6252  6241  0 10:51 ?        00:00:00 nginx: cache manager process  
nobody    6253  6241  0 10:51 ?        00:00:00 nginx: cache loader process  
luming    6430 25051  0 10:51 pts/1    00:00:00 grep --color=auto nginx  
nobody    7996 10419  0 Jan12 ?        00:20:11 nginx: worker process is shutting down  
nobody    8003 10419  0 Jan12 ?        00:20:12 nginx: worker process is shutting down  
root     10419     1  0 Jan08 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx  

After 1 more minute observation:

root      6241     1  0 10:51 ?        00:00:00 nginx: master process /usr/local/nginx/sbin/nginx  
nobody    6242  6241  0 10:51 ?        00:00:01 nginx: worker process        
nobody    6243  6241  0 10:51 ?        00:00:01 nginx: worker process        
nobody    6244  6241  0 10:51 ?        00:00:01 nginx: worker process        
nobody    6245  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6246  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6247  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6248  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6249  6241  0 10:51 ?        00:00:00 nginx: worker process        
nobody    6250  6241  0 10:51 ?        00:00:01 nginx: worker process        
nobody    6251  6241  0 10:51 ?        00:00:02 nginx: worker process        
nobody    6252  6241  0 10:51 ?        00:00:00 nginx: cache manager process  
luming    8680 25051  0 10:56 pts/1    00:00:00 grep --color=auto nginx  

Congratulations! You can upgrade your Nginx server gracefully.