github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/worker/instancepoller/manifold.go (about)

     1  // Copyright 2015 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package instancepoller
     5  
     6  import (
     7  	"time"
     8  
     9  	"github.com/juju/errors"
    10  	"github.com/juju/utils/clock"
    11  
    12  	"github.com/juju/juju/api/base"
    13  	"github.com/juju/juju/api/instancepoller"
    14  	"github.com/juju/juju/environs"
    15  	"github.com/juju/juju/worker"
    16  	"github.com/juju/juju/worker/dependency"
    17  )
    18  
    19  // ManifoldConfig describes the resources used by the instancepoller worker.
    20  type ManifoldConfig struct {
    21  	APICallerName string
    22  	ClockName     string
    23  	Delay         time.Duration
    24  	EnvironName   string
    25  }
    26  
    27  func (config ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    28  	var clock clock.Clock
    29  	if err := context.Get(config.ClockName, &clock); err != nil {
    30  		return nil, errors.Trace(err)
    31  	}
    32  	var environ environs.Environ
    33  	if err := context.Get(config.EnvironName, &environ); err != nil {
    34  		return nil, errors.Trace(err)
    35  	}
    36  
    37  	var apiCaller base.APICaller
    38  	if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    39  		return nil, errors.Trace(err)
    40  	}
    41  	facade := instancepoller.NewAPI(apiCaller)
    42  
    43  	w, err := NewWorker(Config{
    44  		Clock:   clock,
    45  		Delay:   config.Delay,
    46  		Facade:  facade,
    47  		Environ: environ,
    48  	})
    49  	if err != nil {
    50  		return nil, errors.Trace(err)
    51  	}
    52  	return w, nil
    53  }
    54  
    55  // Manifold returns a Manifold that encapsulates the instancepoller worker.
    56  func Manifold(config ManifoldConfig) dependency.Manifold {
    57  	return dependency.Manifold{
    58  		Inputs: []string{
    59  			config.APICallerName,
    60  			config.EnvironName,
    61  			config.ClockName,
    62  		},
    63  		Start: config.start,
    64  	}
    65  }