Cent

======

This release fixes two regressions introduced by v2.2.0.

Improvements:

* [New documentation chapter](https://centrifugal.github.io/centrifugo/server/grpc_api/) about GRPC API in Centrifugo.

Fixes:

* Fix client disconnect in channels with enabled history but disabled recovery
* Fix wrong Push type sent in Redis engine: Leave message was used where Join required

======

This release based on latest refactoring of Centrifuge library. The refactoring opens a road for possible interesting improvements in Centrifugo – such as possibility to use any PUB/SUB broker instead of Redis (here is an [example of possible integration](https://github.com/centrifugal/centrifugo/pull/273) with Nats server), or even combine another broker with existing Redis engine features to still have recovery and presence features. Though these ideas are not implemented in Centrifugo yet. Performance of broadcast operations can be slightly decreased due to some internal changes in Centrifuge library. Also take a close look at backwards incompatible changes section below for one breaking change.

Improvements:

* Track client position in channels with `history_recover` option enabled and disconnect in case of insufficient state. This resolves an edge case when messages could be lost in channels with `history_recover` option enabled after node reconnect to Redis (imagine situation when Redis was unavailable for some time but before Centrifugo node reconnects publisher was able to successfully send a message to channel on another node which reconnected to Redis faster). With new mechanism client won't miss messages though can receive them with some delay. As such situations should be pretty rare on practice it should be a reasonable compromise for applications. New mechanism adds more load on Redis as Centrifugo node periodically polls channel history state. The load is linearly proportional to amount of active channels with `history_recover` option on. By default Centrifugo will check client position in channel stream not often than once in 40 seconds so an additional load on Redis should not be too high
* New options for more flexible conrol over exposed endpoint interfaces and ports: `internal_address`, `tls_external`, `admin_external`. See description calling `centrifugo -h`. [262](https://github.com/centrifugal/centrifugo/pull/262), [#264](https://github.com/centrifugal/centrifugo/pull/264)
* Small optimizations in Websocket and SockjS transports writes
* Server initiated disconnect number metrics labeled with disconnect code

Backwards incompatible changes:

* This release removes a possibility to set `uid` to Publication over API. This feature was not documented in [API reference](https://centrifugal.github.io/centrifugo/server/api/) and `uid` field does not make sense to be kept on client protocol top level as in Centrifugo v2 it does not serve any internal protocol purpose. This is just an application specific information that can be put into `data` payload

Release based on Go 1.12.x

======

This release contains changes in metric paths exported to Graphite, you may need to fix your dashboard when upgrading. Otherwise everything in backwards compatible.

Improvements:

* Refactored export to Graphite, you can now control aggregation interval using `graphite_interval` option (in seconds), during refactoring some magical path transformation was removed so now we have more predictable path generation. Though Graphite paths changed with this refactoring
* Web interface rewritten using modern Javascript stack - latest React, Webpack instead of Gulp, ES6 syntax
* Aggregated metrics also added to `info` command reply. This makes it possible to look at metrics in admin panel too when calling `info` command
* More options can be set over environment variables – see [254](https://github.com/centrifugal/centrifugo/issues/254)
* Healthcheck endpoint – see [252](https://github.com/centrifugal/centrifugo/issues/252)
* New important chapter in docs – [integration guide](https://centrifugal.github.io/centrifugo/guide/)
* Support setting `api_key` when using `Deploy on Heroku` button
* Better timeout handling in Redis engine – client timeout is now bigger than default `redis_read_timeout` so application can more reliably handle errors

Fixes:

* Dockerfile had no correct `WORKDIR` set so it was only possible to use absolute config file path, now this is fixed in [this commit](https://github.com/centrifugal/centrifugo/commit/08be85223aa849d9996c16971f9d049125ade50c)
* Show node version in admin web panel
* Fix possible goroutine leak on client connection close, [commit](https://github.com/centrifugal/centrifuge/commit/a70909c2a2677932fcef0910525ea9497ff9acf2)

======

**Important** If you are using `rpm` or `deb` packages from packagecloud.io then you have to re-run the [installation method of your choice](https://packagecloud.io/FZambia/centrifugo/install) for Centrifugo repository. This is required to update GPG key used. This is a standard process that all packages hosted on packagecloud should do.

Improvements:

* Redis TLS connection support - see [issue in Centrifuge lib](https://github.com/centrifugal/centrifuge/issues/23) and [updated docs](https://centrifugal.github.io/centrifugo/server/engines/#redis-engine)
* Do not send Authorization header in admin web interface when insecure admin mode enabled - helps to protect admin interface with basic authorization (see [240](https://github.com/centrifugal/centrifugo/issues/240))

Fixes:

* Resubscribe only to shard subset of channels after reconnect to Redis ([issue](https://github.com/centrifugal/centrifuge/issues/25))

======

This release has several fixes and performance improvements

Improvements:

* Use latest SockJS url (SockJS version 1.3) for iframe transports
* Improve performance of massive subscriptions to different channels
* Allow dot in namespace names

Fixes:

* Fix of possible deadlock in Redis Engine when subscribe operation fails
* Fix admin web interface [logout issue](https://github.com/centrifugal/web/issues/14) when session expired
* Fix io timeout error when using Redis Engine with sharding enabled
* Fix `checkconfig` command
* Fix typo in metric name - see [233](https://github.com/centrifugal/centrifugo/pull/233)

======

This is a new major version of Centrifugo. New version has some important changes and useful features.

Centrifugo v2 serves the same purpose as Centrifugo v1. Centrifugo v2 is not backwards compatible with v1 – migration to it will require adapting both backend and frontend sides of your application (of course if you decide to migrate).

Centrifugo is now based on new library [centrifuge](https://github.com/centrifugal/centrifuge) for Go language. That library can be used standalone to get even more than Centrifugo server provides – like custom authentication, your own permission management, asynchronous message passing, RPC calls etc.

Highlights of v2:

* Cleaner and more structured client-server protocol defined in protobuf schema. Protocol is more compact because some fields with default values that were sent previously now omitted
* Binary Websocket support (Protobuf). Protobuf allows to transfer data in much more compact and performant way than before. Of course JSON is still the main serialization format
* JWT for authentication and private channel authorization instead of hand-crafted HMAC sign. This means that there is no need in extra libraries to generate connection and subscription tokens. There are [plenty of JWT libraries](https://jwt.io/) for all languages
* Prometheus integration and automatic export of stats to Graphite. Now Centrifugo easily integrates in modern monitoring stack – no need to manually export stats
* Refactored [Javascript](https://github.com/centrifugal/centrifuge-js) (ES6), [Go](https://github.com/centrifugal/centrifuge-go) and [gomobile client](https://github.com/centrifugal/centrifuge-mobile) libraries
* Simplified HTTP API authentication (no request body signing anymore)
* GRPC for server API
* New `presence_stats` API command to get compact presence information - how many clients and unique users in channel
* Structured logging with coloured output during development
* Mechanism to automatically merge several Websocket messages into one to reduce syscall amount thus be more performant under heavy load
* Better recovery algorithm to fix several `recovered` flag false positives
* Goreleaser for automatic releases to Github

Some things were removed from Centrifugo in v2 release:

* Publishing over Redis queue
* Admin websocket endpoint
* Client limited channels
* `history_drop_inactive` channel option now gone
* Websocket prepared message support (though this one can be pushed back at some point).

[New documentation](https://centrifugal.github.io/centrifugo/) contains actual information and tips about migration from v1.

As mentioned above new version uses JWT tokens for authentication and private channel authorization. And there is no API request body signing anymore. This all means that using API clients (like `cent`, `phpcent`, `jscent`, `rubycent`, `gocent` before) is not necessary anymore – you can use any JWT library for your language and just send commands from your code – this is just simple JSON objects. Though API libraries still make sense to simplify integration a bit.

At moment there are no native mobile clients. I.e. `centrifuge-ios` and `centrifuge-android` have not been updated to Centrifugo v2 yet.