github.com/niedbalski/juju@v0.0.0-20190215020005-8ff100488e47/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  	"runtime"
     8  
     9  	"github.com/juju/errors"
    10  	"gopkg.in/juju/names.v2"
    11  	"gopkg.in/juju/worker.v1"
    12  	"gopkg.in/juju/worker.v1/dependency"
    13  
    14  	"github.com/juju/juju/agent"
    15  	"github.com/juju/juju/api/base"
    16  )
    17  
    18  // ManifoldConfig defines the names of the manifolds on which the
    19  // hostkeyreporter worker depends.
    20  type ManifoldConfig struct {
    21  	AgentName     string
    22  	APICallerName string
    23  	RootDir       string
    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.NewFacade == nil {
    38  		return errors.NotValidf("nil NewFacade")
    39  	}
    40  	if config.NewWorker == nil {
    41  		return errors.NotValidf("nil NewWorker")
    42  	}
    43  	return nil
    44  }
    45  
    46  // start is a StartFunc for a Worker manifold.
    47  func (config ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    48  	if runtime.GOOS == "windows" {
    49  		logger.Debugf("no SSH host keys to report on Windows machines")
    50  		return nil, dependency.ErrUninstall
    51  	}
    52  
    53  	if err := config.validate(); err != nil {
    54  		return nil, errors.Trace(err)
    55  	}
    56  	var agent agent.Agent
    57  	if err := context.Get(config.AgentName, &agent); err != nil {
    58  		return nil, errors.Trace(err)
    59  	}
    60  	var apiCaller base.APICaller
    61  	if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    62  		return nil, errors.Trace(err)
    63  	}
    64  
    65  	tag := agent.CurrentConfig().Tag()
    66  	if _, ok := tag.(names.MachineTag); !ok {
    67  		return nil, errors.New("hostkeyreporter may only be used with a machine agent")
    68  	}
    69  
    70  	facade, err := config.NewFacade(apiCaller)
    71  	if err != nil {
    72  		return nil, errors.Trace(err)
    73  	}
    74  
    75  	worker, err := config.NewWorker(Config{
    76  		Facade:    facade,
    77  		MachineId: tag.Id(),
    78  		RootDir:   config.RootDir,
    79  	})
    80  	if err != nil {
    81  		return nil, errors.Trace(err)
    82  	}
    83  	return worker, nil
    84  }
    85  
    86  // Manifold returns a dependency manifold that runs the migration
    87  // worker.
    88  func Manifold(config ManifoldConfig) dependency.Manifold {
    89  	return dependency.Manifold{
    90  		Inputs: []string{
    91  			config.AgentName,
    92  			config.APICallerName,
    93  		},
    94  		Start: config.start,
    95  	}
    96  }