Operators behind reverse proxies that don't reliably forward
X-Forwarded-Host / X-Forwarded-Proto / X-Forwarded-Prefix (manual
nginx setups, on-prem ingresses, custom-domain Fly deploys with
incomplete proxy chains) had no way to force the absolute base URL
the OAuth callback redirects from. The dashboard would reconstruct
the redirect_uri from request headers, the IDP would echo it back,
and the user would land on the wrong host or wrong path — 404.
Add `dashboard.public_url` to config.yaml with env override
HERMES_DASHBOARD_PUBLIC_URL. When set, it is the complete authority —
scheme + host + optional path prefix (e.g. https://example.com/hermes) —
and becomes the base for the OAuth `redirect_uri`. X-Forwarded-Prefix
is IGNORED on this code path because the operator has explicitly
declared the public URL; we no longer need to guess from proxy
headers, and stacking the prefix on top would double-prefix the
common case where the prefix is already baked into public_url.
When unset, the existing proxy_headers + X-Forwarded-Prefix
reconstruction runs untouched. Existing Fly.io deploys continue to
work without configuration — this is purely additive.
Precedence mirrors dashboard.oauth.client_id:
env (non-empty) > config.yaml > reconstructed from request
Implementation:
- hermes_cli/config.py: add dashboard.public_url to DEFAULT_CONFIG
with a multi-paragraph doc comment explaining the use case,
the X-Forwarded-Prefix interaction, and the validation rules.
- hermes_cli/dashboard_auth/prefix.py: factored out the existing
_REJECT_CHARS frozenset, added _normalise_public_url() validator
(requires http/https scheme + non-empty host + no header-injection
chars), _load_dashboard_section() loader (robust to load_config
raising, non-dict shapes), and resolve_public_url() entry point
with the env-overrides-config precedence. A malformed value
silently falls through to ""; the caller treats "" as "reconstruct
from request" so a typo never breaks the login flow.
- hermes_cli/dashboard_auth/routes.py: rewrite _redirect_uri()
docstring to spell out the three resolution tiers; add the
public_url short-circuit before the existing X-Forwarded-Prefix
splicing. Source-level comment notes that X-Forwarded-Prefix is
intentionally ignored when public_url is set so a future reader
doesn't try to "fix" the missing prefix layering.
- cli-config.yaml.example: extend the existing dashboard section
with a public_url block.
- website/docs/user-guide/features/web-dashboard.md: new "Public
URL override" section between the provider configuration and
the OAuth flow walkthrough. Documents the env-vs-config table,
the validation rules, and the `http://` `public_url` ↔ Secure
cookie footgun.
Test coverage — new TestPublicUrlOverride class (8 tests):
- env var overrides request reconstruction (the primary motivating
case)
- config.yaml used when env unset
- env wins over config (precedence pin)
- public_url with a path prefix already baked in (the Q1-a case the
user explicitly chose)
- public_url suppresses X-Forwarded-Prefix layering (defends
against the double-prefix bug)
- trailing slash stripped from public_url (no //auth/callback)
- malformed public_url falls through to reconstruction (six
hostile inputs: javascript:, ftp:, missing scheme, missing host,
quote chars, CRLF injection)
- empty env string doesn't shadow config.yaml entry (CI / Fly
provisioned-but-empty secret case)
Mutation-tested: flipping the precedence in resolve_public_url() trips
exactly test_env_overrides_config_public_url; weakening the validator
(accept any scheme) trips exactly test_malformed_public_url_falls_through_to_reconstruction.
Both other tests in each pair stay green, confirming the suite
discriminates the specific regression each test pins.
a890389b69