John Davidson

Message:

I'm attempting to build an Nginx conf file to communicate to another container via proxy_pass however within Docker compose the way to communicate is via a hostname that matches the target container but in AWS Fargate the way to communicate is on the loopback address. I'm wondering how I build this configuration that can work in both a Docker compose environment and a Fargate environment without having to have two separate Nginx conf files.

Docker compose nginx.conf

fastcgi_pass php:9000;

Fargate nginx.conf

fastcgi_pass 127.0.0.1:9000;

Is there a way that I can nicely handle configurations for both environments without needing two different images or builds?

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My Answer:
One way to handle this is to use environment variables in your Nginx configuration file. You can set an environment variable in your Docker compose file or in your Fargate task definition that specifies the address to use for the fastcgi_pass directive.

For example, you could set an environment variable like PHP_ADDRESS=php in your Docker compose file, and then use that variable in your Nginx configuration file like this:


fastcgi_pass $PHP_ADDRESS:9000;


In your Fargate task definition, you could set the environment variable to 127.0.0.1 instead:


fastcgi_pass 127.0.0.1:9000;


This way, you can use the same Nginx configuration file in both environments, and just set the appropriate environment variable based on where your PHP container is running.