plugins.go

package main

import (
	"fmt"
	"github.com/crosbymichael/log"
	"github.com/crosbymichael/skydock/docker"
	"github.com/crosbymichael/skydock/utils"
	"github.com/robertkrimen/otto"
	"github.com/skynetservices/skydns/msg"
	"io/ioutil"
)

type pluginRuntime struct {
	o *otto.Otto
}

func (r *pluginRuntime) createService(container *docker.Container) (*msg.Service, error) {
	value, err := r.o.ToValue(*container)
	if err != nil {
		return nil, err
	}

	result, err := r.o.Call("createService", nil, value)
	if err != nil {
		return nil, err
	}

	if !result.IsObject() {
		return nil, fmt.Errorf("createService plugin did not return a valid object")
	}

	var (
		obj     = result.Object()
		service = &msg.Service{}
	)

	rawTTL, err := getInt(obj, "TTL")
	if err != nil {
		return nil, err
	}

	rawPort, err := getInt(obj, "Port")
	if err != nil {
		return nil, err
	}

	if service.Name, err = getString(obj, "Service"); err != nil {
		return nil, err
	}
	if service.Version, err = getString(obj, "Instance"); err != nil {
		return nil, err
	}
	if service.Host, err = getString(obj, "Host"); err != nil {
		return nil, err
	}
	if service.Environment, err = getString(obj, "Environment"); err != nil {
		return nil, err
	}
	service.TTL = uint32(rawTTL)
	service.Port = uint16(rawPort)

	// I'm glad that is over
	return service, nil
}

func newRuntime(file string) (*pluginRuntime, error) {
	runtime := otto.New()
	log.Logf(log.INFO, "loading plugins from %s", file)

	content, err := ioutil.ReadFile(file)
	if err != nil {
		return nil, err
	}

	if _, err := runtime.Run(string(content)); err != nil {
		return nil, err
	}

	if err := loadDefaults(runtime); err != nil {
		return nil, err
	}
	return &pluginRuntime{runtime}, nil
}

func loadDefaults(runtime *otto.Otto) error {
	if err := runtime.Set("defaultTTL", ttl); err != nil {
		return err
	}
	if err := runtime.Set("defaultEnvironment", environment); err != nil {
		return err
	}
	if err := runtime.Set("cleanImageName", func(call otto.FunctionCall) otto.Value {
		name := call.Argument(0).String()
		result, _ := otto.ToValue(utils.CleanImageName(name))
		return result
	}); err != nil {
		return err
	}
	if err := runtime.Set("removeSlash", func(call otto.FunctionCall) otto.Value {
		name := call.Argument(0).String()
		result, _ := otto.ToValue(utils.RemoveSlash(name))
		return result
	}); err != nil {
		return err
	}
	return nil
}

// util functions

func getString(obj *otto.Object, name string) (string, error) {
	v, err := obj.Get(name)
	if err != nil {
		return "", err
	}
	return v.ToString()
}

func getInt(obj *otto.Object, name string) (int64, error) {
	v, err := obj.Get(name)
	if err != nil {
		return -1, err
	}
	return v.ToInteger()
}