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How to setup a reverse proxy to your host machine using Docker

kevbradwick profile image Kevin Bradwick Updated on ・2 min read

Recently, I found myself needing a reverse proxy for my local development environment. I had two applications running on different ports, and I wanted them to appear to be served from a single top level domain. This can be useful when you want cookies shared across sub-domains.

For example, I had a single Django application running on port 8000, and a React frontend running on Webpack dev server on 8080. I wanted them both to be accessible from api-app.localhost and web-app.localhost respectively.

Naturally, I turned to Docker for a solution and this is what I came up with. Here is the Docker compose file that uses the Alpine Nginx image to set up the reverse proxy.

It references two Nginx configuration files.

Here's web.conf. You'll notice that there are headers defined that are related to the http version and connection upgrade. This enables Websockets to work that Webpack dev server uses for hot reloading.

And here is the api.conf.

What makes Nginx proxy to your host machine is the use of host.docker.internal in the upstream.

Before starting the containers, there is one thing left to do. Add the two hosts entries to your host file on your host machine. If that's a Linux machine (including macOS) then edit /etc/hosts, and if you are on Windows, edit C:\Windows\System32\drivers\etc\hosts.

127.0.0.1 api-app.localhost web-app.localhost
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And now start the containers!

docker-compose up -d
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When you start the proxy, and both apps are running on your host machine, you'll be able to reach them on http://web-app.localhost:5000 and http://api-app.localhost:5000.

Enjoy!

Discussion (4)

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jasoki profile image
Jason Kim

Unfortunately host.docker.internal isn't supported on Linux at the moment.
github.com/docker/for-linux/issues...

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lysofdev profile image
Esteban Hernández

Awesome post! Could you clarify the last step where you added host entries to the hosts file? Is this necessary if the host machine is only for development?

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kevbradwick profile image
Kevin Bradwick Author

Hi, glad you found it useful. Yes, you'll need to edit the hosts file on your host machine (I've updated the article). And yes, this article is aimed at local development where you need two different apps, running in different processes, to be served from the same top level domain.