Reverse Proxy Service

Allows mapping paths to other URLs, useful for hiding target services. In particular, where the target URL contains authentication information which might otherwise leak.

Configuration

Set one or more environment variables matching this pattern, where EXAMPLE is the path that will redirect to the target URL:

PROXY_MAPPING_EXAMPLE=https://example.com

So, in general, the pattern is PROXY_MAPPING_[redirect key]=[redirect target]. The redirect key is removed from the request, but the rest stays. Here are some examples of that that means in practice:

Path	Resolves to
/example	https://example.com
/example/cats	https://example.com/cats

Washing responses

Some targets (looking at you, Alchemy) return the URL secrets in the response body. Since this is target-dependent, you need to add detection code in getSensitiveStrings if this applies to a new proxy target.

The request interceptor automatically washes all response bodies that goes back to the client by replacing instances of all these sensitive strings with [redacted].

Running

Run in development mode:

PROXY_MAPPING_EXAMPLE=https://example.com npm run dev

Run in docker:

docker build . -t proxy-service
docker run --network=host -e PROXY_MAPPING_EXAMPLE="https://example.com" proxy-service

Regardless of which mode, the service listens on port 5678. It can be tested by sending a request:

curl http://localhost:5678/example