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

     1  // Copyright 2022 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package stateconverter
     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"
    14  	apimachiner "github.com/juju/juju/api/agent/machiner"
    15  	"github.com/juju/juju/api/base"
    16  	"github.com/juju/juju/core/watcher"
    17  )
    18  
    19  // ManifoldConfig provides the dependencies for the
    20  // stateconverter manifold.
    21  type ManifoldConfig struct {
    22  	AgentName     string
    23  	APICallerName string
    24  	Logger        Logger
    25  
    26  	// A constructor for the machiner API which can be overridden
    27  	// during testing. If omitted, the default client for the machiner
    28  	// facade will be automatically used.
    29  	NewMachinerAPI func(base.APICaller) Machiner
    30  }
    31  
    32  // Manifold returns a Manifold that encapsulates the stateconverter worker.
    33  func Manifold(cfg ManifoldConfig) dependency.Manifold {
    34  	return dependency.Manifold{
    35  		Inputs: []string{
    36  			cfg.AgentName,
    37  			cfg.APICallerName,
    38  		},
    39  		Start: cfg.start,
    40  	}
    41  }
    42  
    43  // Validate is called by start to check for bad configuration.
    44  func (cfg ManifoldConfig) Validate() error {
    45  	if cfg.AgentName == "" {
    46  		return errors.NotValidf("empty AgentName")
    47  	}
    48  	if cfg.APICallerName == "" {
    49  		return errors.NotValidf("empty APICallerName")
    50  	}
    51  	if cfg.Logger == nil {
    52  		return errors.NotValidf("nil Logger")
    53  	}
    54  	return nil
    55  }
    56  
    57  // start is a StartFunc for a Worker manifold.
    58  func (cfg ManifoldConfig) start(context dependency.Context) (worker.Worker, error) {
    59  	if err := cfg.Validate(); err != nil {
    60  		return nil, errors.Trace(err)
    61  	}
    62  
    63  	var a agent.Agent
    64  	if err := context.Get(cfg.AgentName, &a); err != nil {
    65  		return nil, errors.Trace(err)
    66  	}
    67  
    68  	tag := a.CurrentConfig().Tag()
    69  	mTag, ok := tag.(names.MachineTag)
    70  	if !ok {
    71  		return nil, errors.NotValidf("%q machine tag", a)
    72  	}
    73  
    74  	machiner, err := cfg.newMachiner(context)
    75  	if err != nil {
    76  		return nil, errors.Trace(err)
    77  	}
    78  
    79  	cfg.Logger.Tracef("starting NotifyWorker for %s", mTag)
    80  	handlerCfg := config{
    81  		machineTag: mTag,
    82  		machiner:   machiner,
    83  		logger:     cfg.Logger,
    84  	}
    85  	w, err := watcher.NewNotifyWorker(watcher.NotifyConfig{
    86  		Handler: NewConverter(handlerCfg),
    87  	})
    88  	if err != nil {
    89  		return nil, errors.Annotate(err, "cannot start controller promoter worker")
    90  	}
    91  	return w, nil
    92  }
    93  
    94  func (cfg ManifoldConfig) newMachiner(context dependency.Context) (Machiner, error) {
    95  	if cfg.NewMachinerAPI != nil {
    96  		machiner := cfg.NewMachinerAPI(nil)
    97  		return machiner, nil
    98  	}
    99  	var apiConn api.Connection
   100  	if err := context.Get(cfg.APICallerName, &apiConn); err != nil {
   101  		return nil, errors.Trace(err)
   102  	}
   103  	return wrapper{m: apimachiner.NewState(apiConn)}, nil
   104  }