Nop client for engine-api about engine-api HOT 6 CLOSED

cc @dongluochen @calavera

from engine-api.

@nishanttotla can you elaborate on how this nopclient is used?

from engine-api.

@duglin it's used here: https://github.com/docker/swarm/blob/master/cluster/engine.go

The primary purpose is to void every action if an Engine goes down in the cluster. It avoids heavy locking around engine/list structs and pending operations. Without this, Swarm performance can degrade.

from engine-api.

I'm pretty sure we don't need that. You can probably achieve the same behavior with a custom Transport that always returns a client.

Steps:

1- Implement the RoundTripper interface:

type NopTrip struct {}
func (NopTrip) RoundTrip(*Request) (*Response, error) {
  return nil, errors.New("nop")
}

2- Create a new HTTPClient using that transport:

client := http.Client{
  Transport: NotTrip{},
}

3- Create an API client with this new client:

api, _ := client.NewClient("...", "", client, ...)

🎉

If this doesn't work, we should consider change the code enough to make it work. This approach is way more scalable than the nopclient because we don't have to add new methods to it every time something is added to the client.

from engine-api.

As a second note, Swarm should consider using the Circuit Breaker pattern rather than this hack:

http://martinfowler.com/bliki/CircuitBreaker.html

An implementation in Go: https://github.com/rubyist/circuitbreaker

from engine-api.

@calavera thanks, that sounds like a great suggestion! I'll close this issue for now, and I think we can consider moving away from the nopclient after the 1.2 release next month.

from engine-api.