github.com/wallyworld/juju@v0.0.0-20161013125918-6cf1bc9d917a/worker/undertaker/manifold.go (about)

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package undertaker
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"github.com/juju/juju/api/base"
     9  	"github.com/juju/juju/environs"
    10  	"github.com/juju/juju/worker"
    11  	"github.com/juju/juju/worker/dependency"
    12  )
    13  
    14  // ManifoldConfig holds the names of the resources used by, and the
    15  // additional dependencies of, an undertaker worker.
    16  type ManifoldConfig struct {
    17  	APICallerName string
    18  	EnvironName   string
    19  
    20  	NewFacade func(base.APICaller) (Facade, error)
    21  	NewWorker func(Config) (worker.Worker, error)
    22  }
    23  
    24  func (config ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    25  
    26  	var apiCaller base.APICaller
    27  	if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    28  		return nil, errors.Trace(err)
    29  	}
    30  	var environ environs.Environ
    31  	if err := context.Get(config.EnvironName, &environ); err != nil {
    32  		return nil, errors.Trace(err)
    33  	}
    34  
    35  	facade, err := config.NewFacade(apiCaller)
    36  	if err != nil {
    37  		return nil, errors.Trace(err)
    38  	}
    39  	worker, err := config.NewWorker(Config{
    40  		Facade:  facade,
    41  		Environ: environ,
    42  	})
    43  	if err != nil {
    44  		return nil, errors.Trace(err)
    45  	}
    46  	return worker, nil
    47  }
    48  
    49  // Manifold returns a dependency.Manifold that runs a worker responsible
    50  // for shepherding a Dying model into Dead and ultimate removal.
    51  func Manifold(config ManifoldConfig) dependency.Manifold {
    52  	return dependency.Manifold{
    53  		Inputs: []string{
    54  			config.APICallerName,
    55  			config.EnvironName,
    56  		},
    57  		Start: config.start,
    58  	}
    59  }