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

     1  // Copyright 2018 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package upgradeseries
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"gopkg.in/juju/names.v2"
     9  	"gopkg.in/juju/worker.v1"
    10  	"gopkg.in/juju/worker.v1/dependency"
    11  
    12  	"github.com/juju/juju/agent"
    13  	"github.com/juju/juju/api/base"
    14  	"github.com/juju/juju/cmd/jujud/agent/engine"
    15  	"github.com/juju/juju/service"
    16  )
    17  
    18  // ManifoldConfig holds the information necessary for the dependency engine to
    19  // to run an upgrade-series worker.
    20  type ManifoldConfig struct {
    21  	AgentName     string
    22  	APICallerName string
    23  
    24  	Logger    Logger
    25  	NewFacade func(base.APICaller, names.Tag) Facade
    26  	NewWorker func(Config) (worker.Worker, error)
    27  }
    28  
    29  // Validate validates the manifold configuration.
    30  func (config ManifoldConfig) Validate() error {
    31  	if config.Logger == nil {
    32  		return errors.NotValidf("nil Logger")
    33  	}
    34  	if config.NewWorker == nil {
    35  		return errors.NotValidf("nil NewWorker function")
    36  	}
    37  	if config.NewFacade == nil {
    38  		return errors.NotValidf("nil NewFacade function")
    39  	}
    40  	return nil
    41  }
    42  
    43  // Manifold returns a dependency manifold that runs an upgrade-series worker,
    44  // using the resource names defined in the supplied config.
    45  func Manifold(config ManifoldConfig) dependency.Manifold {
    46  	typedConfig := engine.AgentAPIManifoldConfig{
    47  		AgentName:     config.AgentName,
    48  		APICallerName: config.APICallerName,
    49  	}
    50  	return engine.AgentAPIManifold(typedConfig, config.newWorker)
    51  }
    52  
    53  // newWorker wraps NewWorker for use in a engine.AgentAPIManifold.
    54  func (config ManifoldConfig) newWorker(a agent.Agent, apiCaller base.APICaller) (worker.Worker, error) {
    55  	if err := config.Validate(); err != nil {
    56  		return nil, errors.Trace(err)
    57  	}
    58  
    59  	// Ensure that we have a machine tag.
    60  	agentCfg := a.CurrentConfig()
    61  	tag, ok := agentCfg.Tag().(names.MachineTag)
    62  	if !ok {
    63  		return nil, errors.Errorf("expected a machine tag, got %v", tag)
    64  	}
    65  
    66  	// Partially apply the NewFacade method and pass it as a factory.
    67  	// This is so the worker can use the API server in different contexts.
    68  	// TODO (manadart 2018-08-30): This behaviour is vestigial.
    69  	// We no longer need a factory and can pass a concrete facade.
    70  	newFacade := func(t names.Tag) Facade {
    71  		return config.NewFacade(apiCaller, t)
    72  	}
    73  
    74  	// Partially apply Upgrader factory function so we only need to request
    75  	// using the getter for the target OS series.
    76  	newUpgrader := func(targetSeries string) (Upgrader, error) {
    77  		return NewUpgrader(targetSeries, service.NewServiceManagerWithDefaults(), config.Logger)
    78  	}
    79  
    80  	cfg := Config{
    81  		Tag:             tag,
    82  		Logger:          config.Logger,
    83  		FacadeFactory:   newFacade,
    84  		Service:         &serviceAccess{},
    85  		UpgraderFactory: newUpgrader,
    86  	}
    87  
    88  	w, err := config.NewWorker(cfg)
    89  	return w, errors.Annotate(err, "starting machine upgrade series worker")
    90  }