# Which Problems Are Solved
ZITADEL currently selects the instance context based on a HTTP header
(see https://github.com/zitadel/zitadel/issues/8279#issue-2399959845 and
checks it against the list of instance domains. Let's call it instance
or API domain.
For any context based URL (e.g. OAuth, OIDC, SAML endpoints, links in
emails, ...) the requested domain (instance domain) will be used. Let's
call it the public domain.
In cases of proxied setups, all exposed domains (public domains) require
the domain to be managed as instance domain.
This can either be done using the "ExternalDomain" in the runtime config
or via system API, which requires a validation through CustomerPortal on
zitadel.cloud.
# How the Problems Are Solved
- Two new headers / header list are added:
- `InstanceHostHeaders`: an ordered list (first sent wins), which will
be used to match the instance.
(For backward compatibility: the `HTTP1HostHeader`, `HTTP2HostHeader`
and `forwarded`, `x-forwarded-for`, `x-forwarded-host` are checked
afterwards as well)
- `PublicHostHeaders`: an ordered list (first sent wins), which will be
used as public host / domain. This will be checked against a list of
trusted domains on the instance.
- The middleware intercepts all requests to the API and passes a
`DomainCtx` object with the hosts and protocol into the context
(previously only a computed `origin` was passed)
- HTTP / GRPC server do not longer try to match the headers to instances
themself, but use the passed `http.DomainContext` in their interceptors.
- The `RequestedHost` and `RequestedDomain` from authz.Instance are
removed in favor of the `http.DomainContext`
- When authenticating to or signing out from Console UI, the current
`http.DomainContext(ctx).Origin` (already checked by instance
interceptor for validity) is used to compute and dynamically add a
`redirect_uri` and `post_logout_redirect_uri`.
- Gateway passes all configured host headers (previously only did
`x-zitadel-*`)
- Admin API allows to manage trusted domain
# Additional Changes
None
# Additional Context
- part of #8279
- open topics:
- "single-instance" mode
- Console UI
* feat: improve instance not found error
* unit tests
* check if is templatable
* lint
* assert
* compile tests
* remove error templates
* link to instance not found page
* fmt
* cleanup
* lint
* feat: return 404 or 409 if org reg disallowed
* fix: system limit permissions
* feat: add iam limits api
* feat: disallow public org registrations on default instance
* add integration test
* test: integration
* fix test
* docs: describe public org registrations
* avoid updating docs deps
* fix system limits integration test
* silence integration tests
* fix linting
* ignore strange linter complaints
* review
* improve reset properties naming
* redefine the api
* use restrictions aggregate
* test query
* simplify and test projection
* test commands
* fix unit tests
* move integration test
* support restrictions on default instance
* also test GetRestrictions
* self review
* lint
* abstract away resource owner
* fix tests
* configure supported languages
* fix allowed languages
* fix tests
* default lang must not be restricted
* preferred language must be allowed
* change preferred languages
* check languages everywhere
* lint
* test command side
* lint
* add integration test
* add integration test
* restrict supported ui locales
* lint
* lint
* cleanup
* lint
* allow undefined preferred language
* fix integration tests
* update main
* fix env var
* ignore linter
* ignore linter
* improve integration test config
* reduce cognitive complexity
* compile
* check for duplicates
* remove useless restriction checks
* review
* revert restriction renaming
* fix language restrictions
* lint
* generate
* allow custom texts for supported langs for now
* fix tests
* cleanup
* cleanup
* cleanup
* lint
* unsupported preferred lang is allowed
* fix integration test
* finish reverting to old property name
* finish reverting to old property name
* load languages
* refactor(i18n): centralize translators and fs
* lint
* amplify no validations on preferred languages
* fix integration test
* lint
* fix resetting allowed languages
* test unchanged restrictions
* fix: find instance by original domain
* return instance not found on invalid origin
* test: ensure correct host validation
* test: instance not found is translated
