80 lines
2.6 KiB
Go
80 lines
2.6 KiB
Go
/*
|
|
Package hystrix is a latency and fault tolerance library designed to isolate
|
|
points of access to remote systems, services and 3rd party libraries, stop
|
|
cascading failure and enable resilience in complex distributed systems where
|
|
failure is inevitable.
|
|
|
|
Based on the java project of the same name, by Netflix. https://github.com/Netflix/Hystrix
|
|
|
|
Execute code as a Hystrix command
|
|
|
|
Define your application logic which relies on external systems, passing your function to Go. When that system is healthy this will be the only thing which executes.
|
|
|
|
hystrix.Go("my_command", func() error {
|
|
// talk to other services
|
|
return nil
|
|
}, nil)
|
|
|
|
Defining fallback behavior
|
|
|
|
If you want code to execute during a service outage, pass in a second function to Go. Ideally, the logic here will allow your application to gracefully handle external services being unavailable.
|
|
|
|
This triggers when your code returns an error, or whenever it is unable to complete based on a variety of health checks https://github.com/Netflix/Hystrix/wiki/How-it-Works.
|
|
|
|
hystrix.Go("my_command", func() error {
|
|
// talk to other services
|
|
return nil
|
|
}, func(err error) error {
|
|
// do this when services are down
|
|
return nil
|
|
})
|
|
|
|
Waiting for output
|
|
|
|
Calling Go is like launching a goroutine, except you receive a channel of errors you can choose to monitor.
|
|
|
|
output := make(chan bool, 1)
|
|
errors := hystrix.Go("my_command", func() error {
|
|
// talk to other services
|
|
output <- true
|
|
return nil
|
|
}, nil)
|
|
|
|
select {
|
|
case out := <-output:
|
|
// success
|
|
case err := <-errors:
|
|
// failure
|
|
}
|
|
|
|
Synchronous API
|
|
|
|
Since calling a command and immediately waiting for it to finish is a common pattern, a synchronous API is available with the Do function which returns a single error.
|
|
|
|
err := hystrix.Do("my_command", func() error {
|
|
// talk to other services
|
|
return nil
|
|
}, nil)
|
|
|
|
Configure settings
|
|
|
|
During application boot, you can call ConfigureCommand to tweak the settings for each command.
|
|
|
|
hystrix.ConfigureCommand("my_command", hystrix.CommandConfig{
|
|
Timeout: 1000,
|
|
MaxConcurrentRequests: 100,
|
|
ErrorPercentThreshold: 25,
|
|
})
|
|
|
|
You can also use Configure which accepts a map[string]CommandConfig.
|
|
|
|
Enable dashboard metrics
|
|
|
|
In your main.go, register the event stream HTTP handler on a port and launch it in a goroutine. Once you configure turbine for your Hystrix Dashboard https://github.com/Netflix/Hystrix/tree/master/hystrix-dashboard to start streaming events, your commands will automatically begin appearing.
|
|
|
|
hystrixStreamHandler := hystrix.NewStreamHandler()
|
|
hystrixStreamHandler.Start()
|
|
go http.ListenAndServe(net.JoinHostPort("", "81"), hystrixStreamHandler)
|
|
*/
|
|
package hystrix
|