Watcher

Watcher 让多个 enforcer 实例之间的 policy 保持同步。当某个 enforcer 更新 policy 时，它会通知其他实例（通过 etcd、Redis 或 Kafka 等消息总线），其他实例随之重新加载或更新自己内存中的 policy。这样你就可以在负载均衡后面运行多个 enforcer，而不会出现权限过期的问题。

Watcher 与 adapter 一样，也在独立的包中实现。下面的列表列出了支持的后端。要新增一个，请提交 issue 或 PR。

Watcher	Type	Author	Description
PostgreSQL WatcherEx	Database	@IguteChung	WatcherEx for PostgreSQL
Redis WatcherEx	KV store	Casbin	WatcherEx for Redis
Redis Watcher	KV store	@billcobbler	Watcher for Redis
Etcd Watcher	KV store	Casbin	Watcher for etcd
TiKV Watcher	KV store	Casbin	Watcher for TiKV
Kafka Watcher	Messaging system	@wgarunap	Watcher for Apache Kafka
NATS Watcher	Messaging system	Soluto	Watcher for NATS
ZooKeeper Watcher	Messaging system	Grepsr	Watcher for Apache ZooKeeper
NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory	Messaging System	@rusenask	Watcher based on Go Cloud Dev Kit that works with leading cloud providers and self-hosted infrastructure
NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory	Messaging System	@bartventer	WatcherEx based on Go Cloud Dev Kit that works with leading cloud providers and self-hosted infrastructure
RocketMQ Watcher	Messaging system	@fmyxyz	Watcher for Apache RocketMQ

Watcher	Type	Author	Description
Etcd Adapter	KV store	@mapleafgo	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Redis WatcherEx	KV store	Casbin	WatcherEx for Redis
Lettuce-Based Redis Watcher	KV store	Casbin	Watcher for Redis based on Lettuce)
PostgreSQL Watcher	Database	Casbin	Watcher for PostgreSQL
Kafka Watcher	Messaging system	Casbin	Watcher for Apache Kafka
ZooKeeper Watcher	Messaging system	Casbin	Watcher for Apache ZooKeeper
RabbitMQ Watcher	Messaging system	Casbin	Watcher for RabbitMQ

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Pub/Sub Watcher	Messaging system	Casbin	Watcher for Google Cloud Pub/Sub
MongoDB Change Streams Watcher	Database	Casbin	Watcher for MongoDB Change Streams
Postgres Watcher	Database	@mcollina	Watcher for PostgreSQL

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Redis Watcher	KV store	ScienceLogic	Watcher for Redis
Redis Async Watcher	KV store	@kevinkelin	Watcher for Redis
PostgreSQL Watcher	Database	Casbin	Watcher for PostgreSQL
RabbitMQ Watcher	Messaging system	Casbin	Watcher for RabbitMQ
MongoDB Watcher	Database	@sanguinedab	Watcher for MongoDB

Watcher	Type	Author	Description
Redis Watcher	KV store	@Sbou	Watcher for Redis

Watcher	Type	Author	Description
Redis Watcher	KV store	CasbinRuby	Watcher for Redis
RabbitMQ Watcher	Messaging system	CasbinRuby	Watcher for RabbitMQ

Watcher	Type	Author	Description
Redis Watcher	KV store	@Tinywan	Watcher for Redis

Watcher	Type	Author	Description
Redis Watcher	KV store	Casbin	Watcher for Redis

WatcherEx

为了支持多个实例之间的增量同步，我们提供了 WatcherEx 接口。该接口可以在 policy 变更时通知其他实例，不过目前还没有 WatcherEx 的实现。我们建议使用 dispatcher 来实现这一功能。

与 Watcher 接口相比，WatcherEx 能够区分收到的更新操作类型，例如 AddPolicy 与 RemovePolicy。

WatcherEx API：

API	Description
SetUpdateCallback(func(string)) error	SetUpdateCallback 配置 watcher 在数据库中的 policy 被其他实例更改时调用的回调函数。经典的回调是 Enforcer.LoadPolicy()。
Update() error	Update 调用其他实例的更新回调来同步它们的 policy。通常在更改数据库中的 policy 之后调用，例如在 Enforcer.SavePolicy()、Enforcer.AddPolicy()、Enforcer.RemovePolicy() 等之后。
Close()	Close 停止并释放 watcher。此后回调函数将不再被调用。
UpdateForAddPolicy(sec, ptype string, params ...string) error	UpdateForAddPolicy 调用其他实例的更新回调来同步它们的 policy。在通过 Enforcer.AddPolicy()、Enforcer.AddNamedPolicy()、Enforcer.AddGroupingPolicy() 和 Enforcer.AddNamedGroupingPolicy() 添加 policy 之后调用。
UpdateForRemovePolicy(sec, ptype string, params ...string) error	UpdateForRemovePolicy 调用其他实例的更新回调来同步它们的 policy。在通过 Enforcer.RemovePolicy()、Enforcer.RemoveNamedPolicy()、Enforcer.RemoveGroupingPolicy() 和 Enforcer.RemoveNamedGroupingPolicy() 移除 policy 之后调用。
UpdateForRemoveFilteredPolicy(sec, ptype string, fieldIndex int, fieldValues ...string) error	UpdateForRemoveFilteredPolicy 调用其他实例的更新回调来同步它们的 policy。在 Enforcer.RemoveFilteredPolicy()、Enforcer.RemoveFilteredNamedPolicy()、Enforcer.RemoveFilteredGroupingPolicy() 和 Enforcer.RemoveFilteredNamedGroupingPolicy() 之后调用。
UpdateForSavePolicy(model model.Model) error	UpdateForSavePolicy 调用其他实例的更新回调来同步它们的 policy。在 Enforcer.SavePolicy() 之后调用。
UpdateForAddPolicies(sec string, ptype string, rules ...[]string) error	UpdateForAddPolicies 调用其他实例的更新回调来同步它们的 policy。在 Enforcer.AddPolicies()、Enforcer.AddNamedPolicies()、Enforcer.AddGroupingPolicies() 和 Enforcer.AddNamedGroupingPolicies() 之后调用。
UpdateForRemovePolicies(sec string, ptype string, rules ...[]string) error	UpdateForRemovePolicies 调用其他实例的更新回调来同步它们的 policy。在 Enforcer.RemovePolicies()、Enforcer.RemoveNamedPolicies()、Enforcer.RemoveGroupingPolicies() 和 Enforcer.RemoveNamedGroupingPolicies() 之后调用。