olscheduler

olscheduler

Extensible scheduler for OpenLambda written in Go.

Installation

Once you have the Go runtime installed in your system just run:

go get github.com/disel-espol/olscheduler

Usage

This program launches an HTTP server that proxies incoming HTTP requests to the HTTP servers that will actually handle the requests, known as "worker nodes". Please note that it is your job to launch the worker nodes and manage them. You can configure almost everything about the scheduler via a Go API or a JSON configuration file using the CLI API.

CLI API

First you must create a configuration file. Here's an example of a configuration to run a scheduler listening on port 9020 using the "Package Aware" load balancing algorithm with two worker nodes listening on ports 9021, and 9022 respectively.

{
  "host":"localhost",
  "port":9020,
  "load-threshold":3,
  "registry":"/tmp/olscheduler-registry.json",
  "balancer":"pkg-aware",
  "workers": [
     "http://localhost:9021",
     "http://localhost:9022"
  ]
}

/tmp/olscheduler-registry.json is another JSON file with an array information about the handler functions. This data is currently only used by the "Package Aware" algorithm. Each item in the array has two attributes:

• handle. The name of the handler funcion.
• pkgs. An array of unique identifier names for the packages that the handler function requires as dependencies.

Here's an example of a registry file with two handler functions: foo and bar.

[
  {
    "handle":"foo",
    "pkgs":["pkg0","pkg1"]
  },
  {
    "handle":"bar",
    "pkgs":["pkg0","pkg2"]
  }
]

Once the files are ready you can launch the scheduler by running:

olscheduler start -c /path/to/config/file 

Go API

This is the simplest method, provided that you are comfortable with Go. Just create a Config struct with the desired configuration and then pass it to the server.Start() function to start the server. Here's an example that creates the same scheduler as the one in the previous section:

package main

import (
	"net/url"

	"github.com/disel-espol/olscheduler/balancer"
	"github.com/disel-espol/olscheduler/config"
	"github.com/disel-espol/olscheduler/server"
)

func main() {
	myConfig := config.CreateDefaultConfig()

	// edit config as you wish
	myConfig.Port = 9020

	// add functions to registry
	myConfig.Registry["foo"] = []string{"pkg0", "pkg1"}
	myConfig.Registry["bar"] = []string{"pkg0", "pkg2"}

	// create workers and set load balancer algorithm
	var loadThreshold uint = 3
	workerUrls := []url.URL{
		url.URL{Scheme: "http", Host: "localhost:8081"},
		url.URL{Scheme: "http", Host: "localhost:8082"},
	}
	myConfig.Balancer = balancer.NewPackageAware(workerUrls, loadThreshold)

	// launch the server
	server.Start(myConfig)
}