etcdwatcher

README

Etcd Watcher

Etcd Watcher is the Etcd watcher for Casbin. With this library, Casbin can synchronize the policy with the database in multiple enforcer instances.

Installation

go get github.com/casbin/etcd-watcher

Simple Example

package main

import (
    "log"

    "github.com/casbin/casbin"
    "github.com/casbin/etcd-watcher"
)

func updateCallback(rev string) {
    log.Println("New revision detected:", rev)
}

func main() {
    // Initialize the watcher.
    // Use the endpoint of etcd cluster as parameter.
    w, _ := etcdwatcher.NewWatcher("http://127.0.0.1:2379")
    
    // Initialize the enforcer.
    e, _ := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")
    
    // Set the watcher for the enforcer.
    e.SetWatcher(w)
    
    // By default, the watcher's callback is automatically set to the
    // enforcer's LoadPolicy() in the SetWatcher() call.
    // We can change it by explicitly setting a callback.
    w.SetUpdateCallback(updateCallback)
    
    // Update the policy to test the effect.
    // You should see "[New revision detected: X]" in the log.
    e.SavePolicy()
}

Getting Help

• Casbin

License

This project is under Apache 2.0 License. See the LICENSE file for the full license text.

Documentation

Index

• func NewWatcher(endpoints []string, keyName string) (persist.Watcher, error)
• type Watcher
  • func (w *Watcher) Close()
  • func (w *Watcher) SetUpdateCallback(callback func(string)) error
  • func (w *Watcher) Update() error

Functions

func NewWatcher

func NewWatcher(endpoints []string, keyName string) (persist.Watcher, error)

NewWatcher is the constructor for Watcher. endpoints is the endpoints for etcd clusters.

Types

type Watcher

type Watcher struct {
	// contains filtered or unexported fields
}

func (*Watcher) Close

func (w *Watcher) Close()

Close closes the Watcher.

func (*Watcher) SetUpdateCallback

func (w *Watcher) SetUpdateCallback(callback 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().

func (*Watcher) Update

func (w *Watcher) 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.