Finally a Decent Conversion with ChatGPT

June 7, 2023

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After many chats with ChatGTP, I finally got a decent conversation that helped me with a problem I was having.

That problem? I was having problems in a Docker Compose application proxying front-end requests from a NGINX container to a back-end NodeJS container.

I’d read several blog posts on the matter, but I wasn’t getting my configuration just right.

Here’s a link to the chat: https://chat.openai.com/share/69ceeebc-7b69-4f65-b44e-9cb468b1e453.

I’ve also copy-pasted it below:

Me

I need to write an nginx configuration file to reverse proxy from one docker container (that the nginx is running) to another docker container that is running nodejs. how do i do this?

ChatGPT

To configure NGINX as a reverse proxy to forward requests from one Docker container to another Docker container running Node.js, you can follow these steps:

Ensure that both containers are on the same Docker network. This allows NGINX to communicate with the Node.js container. You can create a network using the following command:
docker network create my-network
Then, when running the containers, make sure to specify the network:
docker run --network my-network --name nginx-container ...
docker run --network my-network --name nodejs-container ...
Configure the NGINX container by creating an NGINX configuration file. You can create a file named nginx.conf with the following contents:
http {
  upstream nodejs {
    server nodejs-container:3000;  # Replace "nodejs-container" with the actual container name or hostname
  }

  server {
    listen 80;
    server_name your-domain.com;  # Replace with your domain or IP address

    location / {
      proxy_pass http://nodejs;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }
  }
}
In this configuration, the upstream block defines the backend server (Node.js container) and the server block specifies the reverse proxy behavior.

Mount the NGINX configuration file inside the NGINX container when running it. Assuming you have your nginx.conf file in the current directory, you can use the following command to start the NGINX container:
docker run --network my-network --name nginx-container -p 80:80 -v $(pwd)/nginx.conf:/etc/nginx/nginx.conf:ro -d nginx
Here, -v $(pwd)/nginx.conf:/etc/nginx/nginx.conf:ro mounts the configuration file inside the container at the appropriate location.

Make sure the Node.js container is running and accessible within the Docker network on port 3000. Adjust the container name and port in the NGINX configuration file (upstream block) if necessary.

Test the setup by accessing the NGINX container’s IP address or domain name in a web browser. NGINX should reverse proxy the requests to the Node.js container, and you should see the Node.js application’s response.

Remember to replace the placeholder values (your-domain.com, nodejs-container, etc.) with your actual configuration details. Additionally, ensure that you have the necessary DNS or host file entries to resolve the domain name or IP address correctly.

Me

sounds good, but I’m doing this with a docker compose file. how do I do this with docker compose?

ChatGPT

To configure NGINX as a reverse proxy using Docker Compose, you can define the services for NGINX and Node.js containers in a docker-compose.yml file. Here’s an example of how you can set it up:
version: '3'

services:
  nginx:
    image: nginx
    ports:
      - 80:80
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro
    networks:
      - my-network

  nodejs:
    build:
      context: ./path/to/nodejs-app
      dockerfile: Dockerfile
    networks:
      - my-network
In this docker-compose.yml file:

The NGINX service is defined with the nginx image, exposing port 80. It mounts the nginx.conf file into the container as read-only (:ro). Adjust the path to the nginx.conf file as per your directory structure.

The Node.js service is defined with a build context for your Node.js application. Adjust the context value to the appropriate path where your Node.js application’s code is located. You can specify other build-related settings as necessary (e.g., environment variables, volumes, etc.).

Both services are connected to the same Docker network (my-network) to enable communication between the NGINX and Node.js containers.

Ensure you have the nginx.conf file present in the same directory as the docker-compose.yml file.

Once you have the docker-compose.yml file configured, you can start the containers using the following command:
docker-compose up -d
This will build the Node.js container (if necessary) and start both NGINX and Node.js containers in the background. NGINX will be configured as a reverse proxy, forwarding requests to the Node.js container.

Make sure to adjust the nginx.conf file as mentioned in the previous response, especially the server_name directive, if you want to use a specific domain name or IP address.

Me

what changes do i need to make for the upstream part of the nginx configuration file?

ChatGPT

In the NGINX configuration file used within Docker Compose, you need to make a modification to the upstream part. Instead of directly referencing the container name, you can use the service name defined in the Docker Compose file. Here’s an updated version of the NGINX configuration file:
http {
  upstream nodejs {
    server nodejs:3000;  # Use the service name defined in Docker Compose
  }

  server {
    listen 80;
    server_name your-domain.com;  # Replace with your domain or IP address

    location / {
      proxy_pass http://nodejs;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }
  }
}
The only change is in the upstream block where server nodejs-container:3000; is replaced with server nodejs:3000;. By using the service name (nodejs) defined in Docker Compose, NGINX will automatically resolve it to the appropriate container IP address.

Make sure to replace your-domain.com with your actual domain name or IP address in the server_name directive.

With this updated configuration, NGINX will reverse proxy requests to the Node.js container using the service name (nodejs) defined in Docker Compose.

Me

what changes do i need to make to the nginx config file if I only have a certain path that I want to proxy?

ChatGPT

If you only want to proxy a specific path instead of the entire site, you can modify the NGINX configuration file accordingly. Here’s an example that demonstrates how to proxy a specific path:
http {
  upstream nodejs {
    server nodejs:3000;
  }

  server {
    listen 80;
    server_name your-domain.com;

    location /api {
      proxy_pass http://nodejs;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }

    # Add any other configurations for different paths or static files
    # ...

    # Default location for other requests (optional)
    location / {
      # Handle requests for the root or other paths not specified above
      # ...
    }
  }
}
In this configuration:

The location /api block specifies that requests to the /api path will be proxied to the Node.js container.

You can add additional location blocks for different paths or static files, customizing each according to your needs.

The location / block is optional and handles requests for the root path or other paths not specified above. You can add specific directives or behaviors for these requests.

Remember to replace your-domain.com with your actual domain name or IP address.

With this configuration, only requests to the specified path(s) will be reverse proxied to the Node.js container, while other requests can be handled separately based on your configuration.

At this point, I’m having problems with requests to the backend returning 404s with a Cannot GET / and Cannot POST / message… Until I realize nginx is not sending over the entire URL path - it’s just proxying to /.

Me

how do i make it so that the /api part of the location is passed to the backend?

ChatGPT

To pass the /api part of the location to the backend in the NGINX configuration file, you can use the proxy_pass directive with the $request_uri variable. Here’s an updated configuration example:
http {
  upstream nodejs {
    server nodejs:3000;
  }

  server {
    listen 80;
    server_name your-domain.com;

    location /api {
      proxy_pass http://nodejs$request_uri;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }

    # Add any other configurations for different paths or static files
    # ...

    # Default location for other requests (optional)
    location / {
      # Handle requests for the root or other paths not specified above
      # ...
    }
  }
}
By appending $request_uri to the proxy_pass directive, NGINX will pass the entire requested URI (including the /api part) to the backend server.

With this configuration, if a request is made to your-domain.com/api/some/path, NGINX will reverse proxy it to the Node.js container at http://nodejs/api/some/path.

Remember to replace your-domain.com with your actual domain name or IP address.

Feel free to adjust other parts of the configuration to suit your specific requirements, such as adding additional location blocks or customizing headers as needed.

Me

how do i have the same location for a list of different paths?

ChatGPT

To have the same location block for a list of different paths in the NGINX configuration file, you can use a regular expression match with the ~ operator. Here’s an example:
http {
  upstream nodejs {
    server nodejs:3000;
  }

  server {
    listen 80;
    server_name your-domain.com;

    location ~ ^/(path1|path2|path3) {
      proxy_pass http://nodejs$request_uri;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }

    # Add any other configurations for different paths or static files
    # ...

    # Default location for other requests (optional)
    location / {
      # Handle requests for the root or other paths not specified above
      # ...
    }
  }
}
In this configuration:

The location ~ ^/(path1|path2|path3) block uses a regular expression to match multiple paths (path1, path2, path3 in this example).

Requests that match any of the specified paths will be proxied to the Node.js container, with the requested URI preserved.

You can extend the regular expression with additional paths by separating them with the | (pipe) character, like /(path1|path2|path3|path4).

Make sure to adjust the regular expression and paths according to your specific requirements.

Other configurations within the location block, such as setting headers or adding additional directives, can be customized as needed.

Remember to replace your-domain.com with your actual domain name or IP address.

Additionally, you can add further location blocks for different paths or static files, or customize the behavior within the default / location to handle other requests.