How to change nginx config in amazon elastic beanstalk running a docker instance

Question

After i login and the cookie is set I get error 502. When i read the log i get the error:

014/05/17 01:54:43 [error] 11013#0: *8 upstream sent too big header while reading response
header from upstream, client: 83.248.134.236, server: , request: "GET /administration
HTTP/1.1", upstream:

After some fast googling i found: http://developernote.com/2012/09/how-i-fixed-nginx-502-bad-gateway-error/

and I want to try to set fastcgi_buffers and fastcgi_buffer_size to a different value. But how do i set variable on nginx in amazon elasticbeanstalk?

The nginx server is before my docker instance.

Answer 1

I also needed to modify the nginx configuration.

1. Create a script that modifies the nginx configuration (probably you want /etc/nginx/sites-enabled/elasticbeanstalk-nginx-docker.conf) and restarts the nginx service (service nginx restart).
2. You need to execute that script after this nginx config file is written which is after normal ebextensions are executed. This is undocumented, but Evan shared how to do this here: essentially you use an ebextension to copy the script into a directory with hooks that gets executed at the proper time.

An example ebextension config is .ebextensions/01modify_nginx.config:

container_commands:
  copy:
    command: "cp .ebextensions/01rewrite_nginx_config.py /opt/elasticbeanstalk/hooks/appdeploy/enact/"
  make_exe:
    command: "chmod +x /opt/elasticbeanstalk/hooks/appdeploy/enact/01rewrite_nginx_config.py"

This is working nicely now for my project (here is the source where you can see it in action).