| --- |
| id: watchers |
| title: Watchers |
| --- |
| |
| We support to use distributed messaging systems like [etcd](https://github.com/coreos/etcd) to keep consistence between multiple Casbin enforcer instances. So our users can concurrently use multiple Casbin enforcers to handle large number of permission checking requests. |
| |
| Similar to policy storage adapters, we don't put watcher code in the main library. Any support for a new messaging system should be implemented as a watcher. A complete list of Casbin watchers is provided as below. Any 3rd-party contribution on a new watcher is welcomed, please inform us and I will put it in this list:) |
| |
| <!--DOCUSAURUS_CODE_TABS--> |
| |
| <!--Go--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Etcd Watcher](https://github.com/casbin/etcd-watcher) | KV store | Casbin | Watcher for [etcd](https://github.com/coreos/etcd) |
| [Redis Watcher](https://github.com/casbin/redis-watcher) | KV store | Casbin | Watcher for [Redis](http://redis.io/) |
| [Redis Watcher](https://github.com/billcobbler/casbin-redis-watcher) | KV store | [@billcobbler](https://github.com/billcobbler) | Watcher for [Redis](http://redis.io/) |
| [TiKV Watcher](https://github.com/casbin/tikv-watcher) | KV store | Casbin | Watcher for [TiKV](https://github.com/tikv/tikv) |
| [Kafka Watcher](https://github.com/wgarunap/casbin-kafka-watcher) | Messaging system | [@wgarunap](https://github.com/wgarunap) | Watcher for [Apache Kafka](https://kafka.apache.org/) |
| [NATS Watcher](https://github.com/Soluto/casbin-nats-watcher) | Messaging system | [Soluto](https://github.com/Soluto) | Watcher for [NATS](https://nats.io/) |
| [ZooKeeper Watcher](https://github.com/grepsr/casbin-zk-watcher) | Messaging system | [Grepsr](https://github.com/grepsr) | Watcher for [Apache ZooKeeper](https://zookeeper.apache.org/) |
| [NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory](https://github.com/rusenask/casbin-go-cloud-watcher) | Messaging System | [@rusenask](https://github.com/rusenask/) | Watcher based on [Go Cloud Dev Kit](https://gocloud.dev/) that works with leading cloud providers and self-hosted infrastructure | |
| [RocketMQ Watcher](https://github.com/fmyxyz/casbin-rocketmq-watcher) | Messaging system | [@fmyxyz](https://github.com/fmyxyz) | Watcher for [Apache RocketMQ](https://rocketmq.apache.org/) |
| |
| <!--Java--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Etcd Adapter](https://github.com/mapleafgo/jcasbin-extra) | KV store | [@mapleafgo](https://github.com/mapleafgo) | Watcher for [etcd](https://github.com/coreos/etcd) |
| [Redis Watcher](https://github.com/jcasbin/redis-watcher) | KV store | Casbin | Watcher for [Redis](http://redis.io/) |
| [Kafka Watcher](https://github.com/jcasbin/kafka-watcher) | Messaging system | Casbin | Watcher for [Apache Kafka](https://kafka.apache.org/) |
| |
| <!--Node.js--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Etcd Watcher](https://github.com/node-casbin/etcd-watcher) | KV store | Casbin | Watcher for [etcd](https://github.com/coreos/etcd) |
| [Redis Watcher](https://github.com/node-casbin/redis-watcher) | KV store | Casbin | Watcher for [Redis](http://redis.io/) |
| [Pub/Sub Watcher](https://github.com/node-casbin/pubsub-watcher) | Messaging system | Casbin | Watcher for [Google Cloud Pub/Sub](https://cloud.google.com/pubsub/docs) |
| [Postgres Watcher](https://github.com/mcollina/casbin-pg-watcher) | Database | [Matteo Collina](https://github.com/mcollina/) | Watcher for [PostgreSQL](https://www.postgresql.org/) |
| |
| <!--Python--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Redis Watcher](https://github.com/ScienceLogic/flask-casbin-redis-watcher) | KV store | [ScienceLogic](https://github.com/ScienceLogic) | Watcher for [Redis](http://redis.io/) |
| [PostgreSQL Watcher](https://github.com/pycasbin/postgresql-watcher) | Database | Casbin| Watcher for [PostgreSQL](https://www.postgresql.org/) |
| |
| <!--.NET--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Redis Watcher](https://github.com/Sbou/Casbin.NET-Redis-Watcher) | KV store | [@Sbou](https://github.com/Sbou) | Watcher for [Redis](http://redis.io/) |
| |
| <!--Ruby--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Redis Watcher](https://github.com/CasbinRuby/casbin-ruby-redis-watcher) | KV store | [CasbinRuby](https://github.com/CasbinRuby) | Watcher for [Redis](http://redis.io/) |
| [RabbitMQ Watcher](https://github.com/CasbinRuby/casbin-ruby-rabbitmq-watcher) | Messaging system | [CasbinRuby](https://github.com/CasbinRuby) | Watcher for [RabbitMQ](https://www.rabbitmq.com/) |
| |
| <!--PHP--> |
| Watcher | Type | Author | Description |
| ----|------|----|---- |
| [Redis Watcher](https://github.com/Tinywan/casbin) | KV store | [Tinywan](https://github.com/Tinywan) | Watcher for [Redis](http://redis.io/) |
| |
| <!--END_DOCUSAURUS_CODE_TABS--> |
| |
| ## WatcherEx |
| |
| In order to support incremental synchronization between multiple instances, we provide the `WatcherEx` interface. We hope it can notify other instances when the policy changes, but there is currently no implementation of `WatcherEx`. We recommend that you use dispatcher to achieve this. |
| |
| Compared with `Watcher` interface, `WatcherEx` can distinguish what type of update action is received, e.g., `AddPolicy` and `RemovePolicy`. |
| |
| WatcherEx Apis: |
| | api | description | |
| | ---- | ---- | |
| | SetUpdateCallback(func(string)) error | SetUpdateCallback sets the callback function that the watcher will call, when the policy in DB has been changed by other instances. A classic callback is Enforcer.LoadPolicy(). | |
| | Update() error | Update calls the update callback of other instances to synchronize their policy. It is usually called after changing the policy in DB, like Enforcer.SavePolicy(), Enforcer.AddPolicy(), Enforcer.RemovePolicy(), etc. | |
| | Close() | Close stops and releases the watcher, the callback function will not be called any more. | |
| | UpdateForAddPolicy(sec, ptype string, params ...string) error | UpdateForAddPolicy calls the update callback of other instances to synchronize their policy. It is called after a policy is added via Enforcer.AddPolicy(), Enforcer.AddNamedPolicy(), Enforcer.AddGroupingPolicy() and Enforcer.AddNamedGroupingPolicy(). | |
| | UpdateForRemovePolicy(sec, ptype string, params ...string) error | UPdateForRemovePolicy calls the update callback of other instances to synchronize their policy. It is called after a policy is removed by Enforcer.RemovePolicy(), Enforcer.RemoveNamedPolicy(), Enforcer.RemoveGroupingPolicy() and Enforcer.RemoveNamedGroupingPolicy(). | |
| | UpdateForRemoveFilteredPolicy(sec, ptype string, fieldIndex int, fieldValues ...string) error | UpdateForRemoveFilteredPolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.RemoveFilteredPolicy(), Enforcer.RemoveFilteredNamedPolicy(), Enforcer.RemoveFilteredGroupingPolicy() and Enforcer.RemoveFilteredNamedGroupingPolicy(). | |
| | UpdateForSavePolicy(model model.Model) error | UpdateForSavePolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.SavePolicy() | |
| | UpdateForAddPolicies(sec string, ptype string, rules ...[]string) error | UpdateForAddPolicies calls the update callback of other instances to synchronize their policy. It is called after Enforcer.AddPolicies(), Enforcer.AddNamedPolicies(), Enforcer.AddGroupingPolicies() and Enforcer.AddNamedGroupingPolicies(). | |
| | UpdateForRemovePolicies(sec string, ptype string, rules ...[]string) error | UpdateForRemovePolicies calls the update callback of other instances to synchronize their policy. It is called after Enforcer.RemovePolicies(), Enforcer.RemoveNamedPolicies(), Enforcer.RemoveGroupingPolicies() and Enforcer.RemoveNamedGroupingPolicies(). | |
