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

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package migrationminion
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"github.com/juju/juju/agent"
     9  	"github.com/juju/juju/api"
    10  	"github.com/juju/juju/api/base"
    11  	"github.com/juju/juju/worker"
    12  	"github.com/juju/juju/worker/dependency"
    13  	"github.com/juju/juju/worker/fortress"
    14  )
    15  
    16  // ManifoldConfig defines the names of the manifolds on which a
    17  // Worker manifold will depend.
    18  type ManifoldConfig struct {
    19  	AgentName         string
    20  	APICallerName     string
    21  	FortressName      string
    22  	APIOpen           func(*api.Info, api.DialOpts) (api.Connection, error)
    23  	ValidateMigration func(base.APICaller) error
    24  
    25  	NewFacade func(base.APICaller) (Facade, error)
    26  	NewWorker func(Config) (worker.Worker, error)
    27  }
    28  
    29  // validate is called by start to check for bad configuration.
    30  func (config ManifoldConfig) validate() error {
    31  	if config.AgentName == "" {
    32  		return errors.NotValidf("empty AgentName")
    33  	}
    34  	if config.APICallerName == "" {
    35  		return errors.NotValidf("empty APICallerName")
    36  	}
    37  	if config.FortressName == "" {
    38  		return errors.NotValidf("empty FortressName")
    39  	}
    40  	if config.APIOpen == nil {
    41  		return errors.NotValidf("nil APIOpen")
    42  	}
    43  	if config.ValidateMigration == nil {
    44  		return errors.NotValidf("nil ValidateMigration")
    45  	}
    46  	if config.NewFacade == nil {
    47  		return errors.NotValidf("nil NewFacade")
    48  	}
    49  	if config.NewWorker == nil {
    50  		return errors.NotValidf("nil NewWorker")
    51  	}
    52  	return nil
    53  }
    54  
    55  // start is a StartFunc for a Worker manifold.
    56  func (config ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    57  	if err := config.validate(); err != nil {
    58  		return nil, errors.Trace(err)
    59  	}
    60  	var agent agent.Agent
    61  	if err := context.Get(config.AgentName, &agent); err != nil {
    62  		return nil, errors.Trace(err)
    63  	}
    64  	var apiCaller base.APICaller
    65  	if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    66  		return nil, errors.Trace(err)
    67  	}
    68  	var guard fortress.Guard
    69  	if err := context.Get(config.FortressName, &guard); err != nil {
    70  		return nil, errors.Trace(err)
    71  	}
    72  
    73  	facade, err := config.NewFacade(apiCaller)
    74  	if err != nil {
    75  		return nil, errors.Trace(err)
    76  	}
    77  	worker, err := config.NewWorker(Config{
    78  		Agent:             agent,
    79  		Facade:            facade,
    80  		Guard:             guard,
    81  		APIOpen:           config.APIOpen,
    82  		ValidateMigration: config.ValidateMigration,
    83  	})
    84  	if err != nil {
    85  		return nil, errors.Trace(err)
    86  	}
    87  	return worker, nil
    88  }
    89  
    90  // Manifold returns a dependency manifold that runs the migration
    91  // worker.
    92  func Manifold(config ManifoldConfig) dependency.Manifold {
    93  	return dependency.Manifold{
    94  		Inputs: []string{
    95  			config.AgentName,
    96  			config.APICallerName,
    97  			config.FortressName,
    98  		},
    99  		Start: config.start,
   100  	}
   101  }