Cent

======

Fixes

* Fix non-working bidirectional emulation in multi-node case [590](https://github.com/centrifugal/centrifugo/issues/590)
* Process client channels for no-credentials case also, see issue [581](https://github.com/centrifugal/centrifugo/issues/581)
* Fix setting `allow_positioning` for top-level namespace, [commit](https://github.com/centrifugal/centrifugo/commit/dbaf01776ff294ee6731cd5422146c0f23107cce)

Misc

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This release contains an important fix of Centrifugo memory leak. The leak happens in all setups which use Centrifugo v4.0.2 or v4.0.3.

Fixes

* Fix goroutine leak on connection close introduced by v4.0.2, [commit](https://github.com/centrifugal/centrifuge/commit/82107b38a42561ca022d50f7ee2ca038a6f120e9)

Misc

======

Fixes

* Fix insensitive case match for granular proxy headers, [572](https://github.com/centrifugal/centrifugo/issues/572)

======

This release contains one more fix of v4 degradation (not respecting `force_push_join_leave` option for top-level namespace), comes with updated admin web UI and other improvements.

Fixes

* Handle `force_push_join_leave` option set for top-level namespace – it was ignored so join/leave messages were not delivered to clients, [commit](https://github.com/centrifugal/centrifugo/commit/a2409fb7465e348275d87a9d94db5bea5bae357d)
* Properly handle `b64data` in server publish API, [commit](https://github.com/centrifugal/centrifugo/commit/e205bca549c6104b608273e2a9c8a777f0083d92)

Improvements

* Updated admin web UI. It now uses modern React stack, fresh look based on Material UI and several other small improvements. See [566](https://github.com/centrifugal/centrifugo/pull/566) for more details
* Case-insensitive http proxy header configuration [558](https://github.com/centrifugal/centrifugo/pull/558)
* Use Alpine 3.16 instead of 3.13 for Docker builds, [commit](https://github.com/centrifugal/centrifugo/commit/0c1332ffb335266ce4ff88750985c27263b13de2)
* Add missing empty object results to API command responses, [commit](https://github.com/centrifugal/centrifugo/commit/bdfdc1eeadd99eb4e30162c70accb02b1b1e32d2)
* Disconnect clients in case of inappropriate protocol [centrifugal/centrifuge256](https://github.com/centrifugal/centrifuge/pull/256)

Misc

======

This release contains an important fix of v4 degradation (proxying user limited channel) and comes with several nice improvements.

Fixes

* Avoid proxying user limited channel [550](https://github.com/centrifugal/centrifugo/pull/550)
* Look at subscription source to handle token subs change [545](https://github.com/centrifugal/centrifugo/pull/545)

Improvements

* Configure server-to-client ping/pong intervals [551](https://github.com/centrifugal/centrifugo/pull/551), [docs](https://centrifugal.dev/docs/transports/overview#pingpong-behavior)
* Option `client_connection_limit` to set client connection limit for a single Centrifugo node [546](https://github.com/centrifugal/centrifugo/pull/546), [docs](https://centrifugal.dev/docs/server/configuration#client_connection_limit)
* Option `api_external` to expose API handler on external port [536](https://github.com/centrifugal/centrifugo/issues/536)
* Use `go.uber.org/automaxprocs` to set GOMAXPROCS [528](https://github.com/centrifugal/centrifugo/pull/528), this may help to automatically improve Centrifugo performance when it's running in an environment with cgroup-restricted CPU resources (Docker, Kubernetes).
* Nats broker: use push format from client protocol v2 [542](https://github.com/centrifugal/centrifugo/pull/542)

Misc

* While working on [Centrifuge](https://github.com/centrifugal/centrifuge) lib [j178](https://github.com/j178) found a scenario where connection to Redis could leak, this was not observed and reported in Centrifugo outside the test suite, but it seems that theoretically connections to Redis from Centrifugo could leak with time if the network between Centrifugo and Redis is unstable. This release contains an updated Redis engine which eliminates this.

======

New v4 release puts Centrifugo to the next level in terms of client protocol performance, WebSocket fallback simplicity, SDK ecosystem and channel security model. This is a major release with breaking changes according to our [Centrifugo v4 roadmap](https://github.com/centrifugal/centrifugo/issues/500).

Several important documents we have at this point can help you get started with Centrifugo v4:

* Centrifugo v4 [release blog post](https://centrifugal.dev/blog/2022/07/10/centrifugo-v4-released)
* Centrifugo v3 -> v4 [migration guide](https://centrifugal.dev/docs/getting-started/migration_v4)
* Client SDK API [specification](https://centrifugal.dev/docs/transports/client_api)
* Updated [quickstart tutorial](https://centrifugal.dev/docs/getting-started/quickstart)

Highlights

* New client protocol iteration and unified client SDK API. See client SDK API [specification](https://centrifugal.dev/docs/transports/client_api).
* All SDKs now support all the core features of Centrifugo - see [feature matrix](https://centrifugal.dev/docs/transports/client_sdk#sdk-feature-matrix)
* Our own WebSocket bidirectional emulation layer based on HTTP-streaming and SSE (EventSource). Without sticky session requirement for a distributed case. See details in release post and [centrifuge-js README](https://github.com/centrifugal/centrifuge-js/tree/master#bidirectional-emulation)
* SockJS is still supported but DEPRECATED
* Redesigned, more efficient PING-PONG – see details in release post
* Optimistic subscriptions support (implemented in `centrifuge-js` only at this point) – see details in release post
* Secure by default channel namespaces – see details in release post
* Private channel and subscription JWT concepts revised – see details in release post
* Possibility to enable join/leave, recovery and positioning from the client-side
* Experimental HTTP/3 support - see details in release post
* Experimental WebTransport support - see details in release post
* Avoid sending JSON in WebSocket Close frame reason
* Temporary flag for errors, allows resilient behavior of Subscriptions
* `gensubtoken` and `checksubtoken` helper cli commands as subscription JWT now behaves similar to connection JWT
* Legacy options removed, some options renamed, see [migration guide](https://centrifugal.dev/docs/getting-started/migration_v4) for details.
* `meta` attached to a connection now updated upon connection refresh
* `centrifuge-js` migrated to Typescript
* The docs on [centrifugal.dev](https://centrifugal.dev/) were updated for v4, docs for v3 are still there but under version switch widget.
* Use constant time compare function to compare admin_password and api_key [527](https://github.com/centrifugal/centrifugo/pull/527)

Misc