github.com/juju/juju@v0.0.0-20240327075706-a90865de2538/worker/hostkeyreporter/manifold.go (about)

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package hostkeyreporter
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"github.com/juju/names/v5"
     9  	"github.com/juju/worker/v3"
    10  	"github.com/juju/worker/v3/dependency"
    11  
    12  	"github.com/juju/juju/agent"
    13  	"github.com/juju/juju/api/base"
    14  )
    15  
    16  // ManifoldConfig defines the names of the manifolds on which the
    17  // hostkeyreporter worker depends.
    18  type ManifoldConfig struct {
    19  	AgentName     string
    20  	APICallerName string
    21  	RootDir       string
    22  
    23  	NewFacade func(base.APICaller) (Facade, error)
    24  	NewWorker func(Config) (worker.Worker, error)
    25  }
    26  
    27  // validate is called by start to check for bad configuration.
    28  func (config ManifoldConfig) validate() error {
    29  	if config.AgentName == "" {
    30  		return errors.NotValidf("empty AgentName")
    31  	}
    32  	if config.APICallerName == "" {
    33  		return errors.NotValidf("empty APICallerName")
    34  	}
    35  	if config.NewFacade == nil {
    36  		return errors.NotValidf("nil NewFacade")
    37  	}
    38  	if config.NewWorker == nil {
    39  		return errors.NotValidf("nil NewWorker")
    40  	}
    41  	return nil
    42  }
    43  
    44  // start is a StartFunc for a Worker manifold.
    45  func (config ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    46  	if err := config.validate(); err != nil {
    47  		return nil, errors.Trace(err)
    48  	}
    49  	var agent agent.Agent
    50  	if err := context.Get(config.AgentName, &agent); err != nil {
    51  		return nil, errors.Trace(err)
    52  	}
    53  	var apiCaller base.APICaller
    54  	if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    55  		return nil, errors.Trace(err)
    56  	}
    57  
    58  	tag := agent.CurrentConfig().Tag()
    59  	if _, ok := tag.(names.MachineTag); !ok {
    60  		return nil, errors.New("hostkeyreporter may only be used with a machine agent")
    61  	}
    62  
    63  	facade, err := config.NewFacade(apiCaller)
    64  	if err != nil {
    65  		return nil, errors.Trace(err)
    66  	}
    67  
    68  	worker, err := config.NewWorker(Config{
    69  		Facade:    facade,
    70  		MachineId: tag.Id(),
    71  		RootDir:   config.RootDir,
    72  	})
    73  	if err != nil {
    74  		return nil, errors.Trace(err)
    75  	}
    76  	return worker, nil
    77  }
    78  
    79  // Manifold returns a dependency manifold that runs the migration
    80  // worker.
    81  func Manifold(config ManifoldConfig) dependency.Manifold {
    82  	return dependency.Manifold{
    83  		Inputs: []string{
    84  			config.AgentName,
    85  			config.APICallerName,
    86  		},
    87  		Start: config.start,
    88  	}
    89  }