github.com/niedbalski/juju@v0.0.0-20190215020005-8ff100488e47/worker/externalcontrollerupdater/manifold.go (about)

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package externalcontrollerupdater
     5  
     6  import (
     7  	"github.com/juju/clock"
     8  	"github.com/juju/errors"
     9  	"gopkg.in/juju/worker.v1"
    10  	"gopkg.in/juju/worker.v1/dependency"
    11  
    12  	"github.com/juju/juju/api/base"
    13  	"github.com/juju/juju/api/externalcontrollerupdater"
    14  )
    15  
    16  // ManifoldConfig describes the resources used by an
    17  // externalcontrollerupdater worker.
    18  type ManifoldConfig struct {
    19  	APICallerName string
    20  
    21  	NewExternalControllerWatcherClient NewExternalControllerWatcherClientFunc
    22  }
    23  
    24  // Validate validates the manifold configuration.
    25  func (cfg ManifoldConfig) Validate() error {
    26  	if cfg.APICallerName == "" {
    27  		return errors.NotValidf("empty APICallerName")
    28  	}
    29  	if cfg.NewExternalControllerWatcherClient == nil {
    30  		return errors.NotValidf("nil NewExternalControllerWatcherClient")
    31  	}
    32  	return nil
    33  }
    34  
    35  // Manifold returns a Manifold that runs an externalcontrollerupdater worker.
    36  func Manifold(config ManifoldConfig) dependency.Manifold {
    37  	return dependency.Manifold{
    38  		Inputs: []string{
    39  			config.APICallerName,
    40  		},
    41  		Start: func(context dependency.Context) (worker.Worker, error) {
    42  			if err := config.Validate(); err != nil {
    43  				return nil, errors.Trace(err)
    44  			}
    45  			var apiCaller base.APICaller
    46  			if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    47  				return nil, err
    48  			}
    49  			return manifoldStart(apiCaller, config.NewExternalControllerWatcherClient)
    50  		},
    51  	}
    52  }
    53  
    54  // manifoldStart returns a unitassigner worker using the supplied APICaller.
    55  func manifoldStart(
    56  	apiCaller base.APICaller,
    57  	newExternalControllerWatcherClient NewExternalControllerWatcherClientFunc,
    58  ) (worker.Worker, error) {
    59  	client := externalcontrollerupdater.New(apiCaller)
    60  	worker, err := New(
    61  		client,
    62  		newExternalControllerWatcherClient,
    63  		clock.WallClock,
    64  	)
    65  	if err != nil {
    66  		return nil, errors.Trace(err)
    67  	}
    68  	return worker, nil
    69  }