request-balancer

HTTP(s) Local load balancer client based on request-promise : https://www.npmjs.com/package/request-promise

installation

npm install request-balancer

Description

The main porpose of this library is to provide a basic HTTP(s) load balancer client to send http request to a microservice composed of several nodes, as netflix OSS java 'Ribbon' library does.

Now imagine you have deploy three instance of your microservice with the following host and port:

node	host	port
#1	node1.test.domain.org	3010
#2	node2.test.domain.org	3020
#3	node3.test.domain.org	3070

Each instance expose a service to get the weather using the following request : GET http://{host:port}/weather?town=paris

To load balance over this three instances you must use request-balancer as follow:

 
let Rpb = require('../request-balancer');
 
let rpb = new Rpb(['http://node1.test.domain.org:3010', 'http://node2.test.domain.org:3020', 'http://node3.test.domain.org:3070'], {
            timeout: 2000,
            maxError: 1
        });
 
rpb.send({
    path:'/weather?town=paris',
    method:'GET'
}).then(function(response){
    console.log(response);
});

Request balancer come as class you must instanciate to keep the context of round robin balancing

new Rpb(endpoints,options)

• endpoints : is an array of uri of all the endpoints to load balance on
• options
  • timeout : in order to 'fail fast', it is possible to set the timeout on a request send to endpoints. If it timeout, load balancer send the request to the next endpoint.
  • maxError : maximum number of consecutive error after the library consider the endpoint as dead, error counter are reset every healthCheckPeriod
  • healthCheckPeriod : period after the library perform a health check on each endpoint

rpb.send(options)

• options same as original request library except:
  • path replace the uri field of request, instead of providing the full uri only the uri path is provided