[Bug]: express-rate-limit validation error when using with reverse proxy

[ankel]

Verified issue does not already exist?

• [X] I have searched and found no existing issue

What happened?

Reproduce steps: run docker compose up with the following configurations

compose.yaml

services:
  traefik:
    image: traefik:latest
    restart: unless-stopped
    ports:
      - "80:80"
    volumes:
      - "./traefik.yaml:/etc/traefik/traefik.yaml"
      - "./traefik/data:/data"
      - "/var/run/docker.sock:/var/run/docker.sock"

  actual-server:
    image: actualbudget/actual-server:latest-alpine
    restart: unless-stopped
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.actual-server.rule=PathPrefix(`/actual-budget`)"
      - "traefik.http.routers.actual-server.entrypoints=web"
      - "traefik.http.services.actual-server.loadbalancer.server.port=5006"
    volumes:
      - ./actual-data:/data

traefik.yaml

entryPoints:
  web:
    address: ":80"

providers:
  docker: {}

What error did you receive?

Once it's running, curl localhost:80/actual-budget will print the following error in the log:

ValidationError: The 'X-Forwarded-For' header is set but the Express 'trust proxy' setting is false (default). This could indicate a misconfiguration which would prevent express-rate-limit from accurately identifying users. See https://express-rate-limit.github.io/ERR_ERL_UNEXPECTED_X_FORWARDED_FOR/ for more information.
    at _Validations.<anonymous> (file:///app/node_modules/express-rate-limit/dist/index.mjs:154:15)
    at _Validations.wrap (file:///app/node_modules/express-rate-limit/dist/index.mjs:287:18)
    at _Validations.xForwardedForHeader (file:///app/node_modules/express-rate-limit/dist/index.mjs:152:10)
    at Object.keyGenerator (file:///app/node_modules/express-rate-limit/dist/index.mjs:516:19)
    at file:///app/node_modules/express-rate-limit/dist/index.mjs:569:32
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async file:///app/node_modules/express-rate-limit/dist/index.mjs:550:5 {
  code: 'ERR_ERL_UNEXPECTED_X_FORWARDED_FOR',
  help: 'https://express-rate-limit.github.io/ERR_ERL_UNEXPECTED_X_FORWARDED_FOR/'
}

Where are you hosting Actual?

Docker

What browsers are you seeing the problem on?

Other

Operating System

Linux

[djm2k]

I've hotfixed this for my use here, by:

• repurposing the ACTUAL_TRUSTED_PROXIES env var as a number
• passing it to app.set('trust proxy', numberOfProxies) as recommended here
• modifying validateAuthHeader to just return true
  • not sure the implications of this, I assume express-rate-limit's proxy checker is OK? I use Authelia as another layer anyhow

Edit: See the below PR for a more thought-out approach, re-purposing the ACTUAL_TRUSTED_PROXIES env var.

[xadips]

Yup happens to me as well with nginx-proxy-manager setup since 24.8.0

[latetedemelon]

Confirmed this affects NPM starting with version 24.8.0