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

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package identityfilewriter
     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  	apiagent "github.com/juju/juju/api/agent"
    14  	"github.com/juju/juju/api/base"
    15  	"github.com/juju/juju/cmd/jujud/agent/engine"
    16  	"github.com/juju/juju/state/multiwatcher"
    17  	jworker "github.com/juju/juju/worker"
    18  )
    19  
    20  // ManifoldConfig defines the names of the manifolds on which a Manifold will depend.
    21  type ManifoldConfig engine.AgentAPIManifoldConfig
    22  
    23  // Manifold returns a dependency manifold that runs an identity file writer worker,
    24  // using the resource names defined in the supplied config.
    25  func Manifold(config ManifoldConfig) dependency.Manifold {
    26  	typedConfig := engine.AgentAPIManifoldConfig(config)
    27  	return engine.AgentAPIManifold(typedConfig, newWorker)
    28  }
    29  
    30  // newWorker trivially wraps NewWorker for use in a engine.AgentAPIManifold.
    31  func newWorker(a agent.Agent, apiCaller base.APICaller) (worker.Worker, error) {
    32  	cfg := a.CurrentConfig()
    33  
    34  	// Grab the tag and ensure that it's for a machine.
    35  	tag, ok := cfg.Tag().(names.MachineTag)
    36  	if !ok {
    37  		return nil, errors.New("this manifold may only be used inside a machine agent")
    38  	}
    39  
    40  	// Get the machine agent's jobs.
    41  	apiSt, err := apiagent.NewState(apiCaller)
    42  	if err != nil {
    43  		return nil, errors.Trace(err)
    44  	}
    45  	entity, err := apiSt.Entity(tag)
    46  	if err != nil {
    47  		return nil, err
    48  	}
    49  	var isModelManager bool
    50  	for _, job := range entity.Jobs() {
    51  		if job == multiwatcher.JobManageModel {
    52  			isModelManager = true
    53  			break
    54  		}
    55  	}
    56  
    57  	if !isModelManager {
    58  		return nil, dependency.ErrMissing
    59  	}
    60  
    61  	return NewWorker(cfg)
    62  }
    63  
    64  var NewWorker = func(agentConfig agent.Config) (worker.Worker, error) {
    65  	inner := func(<-chan struct{}) error {
    66  		return agent.WriteSystemIdentityFile(agentConfig)
    67  	}
    68  	return jworker.NewSimpleWorker(inner), nil
    69  }