Zero Downtime deployment for different app version

1. Located your built program .so application, if you have no any idea of this, please refer to this Sample Application

2. Assumed that your application called "myApp-1.0.0.so" which located at "/etc/nginx/apps/myApp-1.0.0.so", then go to nginx and add one the content below

server {
  listen 8888;
  ...
  ngx_http_c_func_link_lib "/etc/nginx/apps/myApp-1.0.0.so";
  ...
  ...
  location = /testCFunGreeting {
      # if not variable specified, direct write response out
      ngx_http_c_func_call "my_app_simple_get_greeting"; 
  }
}

3. Then start the nginx.

4. Somehow you have built new version of your application, then you named it as "myApp-2.0.0.so" which you stored it at "/etc/nginx/apps/myApp-2.0.0.so", then please go to nginx and change the content below

from ngx_http_c_func_link_lib "/etc/nginx/apps/myApp-1.0.0.so"; to ngx_http_c_func_link_lib "/etc/nginx/apps/myApp-2.0.0.so";

5. then reload nginx by sudo nginx -s reload

6. Congratulation! you have just done the zero deployment. Now you can safely backup/archive/delete your old version of your app.

## 7. Caution! Please do not direct overwrite the new .so application to current one while nginx is running, it will crash the nginx module, please follow step 1 to 6 to achieve the deployment