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nginx-port

README.md

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Intro

This project shows HOWTO create a Docker container using nginx where the nginx server can dynamically acquire values from environment variables passed in by docker (e.g. using the -e command).

Docker Hub

Image

Docker

Build it.

./build.sh

Run it.

docker run -p 81:81 -e PORT=81 --rm nginx-port:local
docker run -p 82:82 -e PORT=82 --rm nginx-port:local
docker run -p 83:83 -e PORT=83 --rm nginx-port:local

Observe it.

Notes

Note the following.

  • The Angular application is a vanilla one using the ng-cli command ng new. This application is necessary to show only a toy deployment of a client-side application with nginx as the HTTP server.
  • In the Dockerfile, we have CMD ["nginx", "-g", "daemon off;"] to force nginx to run in the foreground. The -g is a global setting. This option of turning off daemon mode is useful for debugging and should be turned off for production.
  • Note that we are using envsubst to acquire the values of the environment variables. This approach is the recommended way. Look at the docker-entrypoint.sh script. We are using a nginx configuration template nginx-default.conf.template to help.
  • Elsewhere, people suggest using openresty. This approach took me down a rabbit hole. Supposedly, openresty can use lua and perl inside the nginx.conf file to acquire environment variables. If you figure out HOTWO do this approach successfully, email me. ;)
  • This approach might help with Azure's Linux App Service VNET Integration where they pass in -e PORT=<some_port> (<some_port> is a random value) to the container. The example they show is with a Node.js Express app which has the process.env.PORT API access to environment variables (server-side applications like flask are also able to acquire environment variable values too e.g. os.getenv('PORT', 80)). However, with a client-side application like Angular hosted on nginx, this approach will help (as Angular will not have those API hooks).

Take a Look!

Check out Charles Petzold. He's my favorite author when it comes to programming books.

Citation

@misc{oneoffcoder_nginx_port_2019, 
title={Docker container show how to dynamically set ports from environment variable}, 
url={https://github.com/oneoffcoder/docker-containers/tree/master/nginx-port}, 
journal={GitHub},
author={One-Off Coder}, 
year={2019}, 
month={Jul}}