## Problem
`generateFrontConfig()` writes `window._env_.REACT_APP_SERVER_BASE_URL =
process.env.SERVER_URL` unconditionally. The frontend then pins to that
absolute URL. For self-hosted deployments reachable from multiple
hostnames (Tailscale IP, LAN IP, internal DNS, SSH tunnel to localhost,
public DNS), only the one matching `SERVER_URL` works — others hit CORS
errors or unreachable hosts because the frontend tries to call the API
at the configured URL, not the one the user came in via.
The frontend already supports the right fallback:
`packages/twenty-front/src/config/index.ts:20-21` reads
`window._env_?.REACT_APP_SERVER_BASE_URL` and falls back to
`getDefaultUrl()` (which uses `window.location`) when the env var is
absent. But the server-side `generateFrontConfig` always populates
`_env_`, so the fallback never runs.
## Fix
One file: `packages/twenty-server/src/utils/generate-front-config.ts`.
Add a `FRONT_AUTO_BASE_URL=true` opt-in (also triggered when
`SERVER_URL` is unset entirely). When the toggle is on, inject
`window._env_ = {}` so the frontend's existing `getDefaultUrl()`
fallback resolves the origin from `window.location` at runtime.
## Backwards compatibility
When `SERVER_URL` is set AND `FRONT_AUTO_BASE_URL` is unset (or anything
other than `'true'`): unchanged — `REACT_APP_SERVER_BASE_URL:
process.env.SERVER_URL` is injected exactly as before.
The toggle is strictly additive. Existing single-hostname deployments
are not affected.
## Use case
Self-hosted Twenty reachable via:
- `http://100.115.12.29` over Tailscale
- `http://localhost:4440` over SSH tunnel
- `http://twenty.internal` over LAN DNS
- `http://crm.example.com` public
With `FRONT_AUTO_BASE_URL=true`, all four paths work without rebuilds or
per-hostname server processes.
## Test plan
- [ ] `SERVER_URL=http://x.com` (toggle unset) → `<script>window._env_ =
{"REACT_APP_SERVER_BASE_URL":"http://x.com"};</script>` (unchanged from
main)
- [ ] `SERVER_URL` unset → `<script>window._env_ = {};</script>` (new
fallback path)
- [ ] `SERVER_URL=http://x.com FRONT_AUTO_BASE_URL=true` →
`<script>window._env_ = {};</script>` (toggle wins)
- [ ] `FRONT_AUTO_BASE_URL=false SERVER_URL=http://x.com` → unchanged
(only `'true'` triggers the toggle)
---------
Co-authored-by: martmull <martmull@hotmail.fr>
LazyBouy
88b77cb699