github.com/makyo/juju@v0.0.0-20160425123129-2608902037e9/cmd/jujud/agent/machine/servinginfo_setter.go (about)

     1  // Copyright 2015 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package machine
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"github.com/juju/names"
     9  
    10  	coreagent "github.com/juju/juju/agent"
    11  	apiagent "github.com/juju/juju/api/agent"
    12  	"github.com/juju/juju/api/base"
    13  	"github.com/juju/juju/worker"
    14  	"github.com/juju/juju/worker/dependency"
    15  )
    16  
    17  // ServingInfoSetterConfig provides the dependencies for the
    18  // servingInfoSetter manifold.
    19  type ServingInfoSetterConfig struct {
    20  	AgentName     string
    21  	APICallerName string
    22  }
    23  
    24  // ServingInfoSetterManifold defines a simple start function which
    25  // runs after the API connection has come up. If the machine agent is
    26  // a controller, it grabs the state serving info over the API and
    27  // records it to agent configuration, and then stops.
    28  func ServingInfoSetterManifold(config ServingInfoSetterConfig) dependency.Manifold {
    29  	return dependency.Manifold{
    30  		Inputs: []string{
    31  			config.AgentName,
    32  			config.APICallerName,
    33  		},
    34  		Start: func(context dependency.Context) (worker.Worker, error) {
    35  			// Get the agent.
    36  			var agent coreagent.Agent
    37  			if err := context.Get(config.AgentName, &agent); err != nil {
    38  				return nil, err
    39  			}
    40  
    41  			// Grab the tag and ensure that it's for a machine.
    42  			tag, ok := agent.CurrentConfig().Tag().(names.MachineTag)
    43  			if !ok {
    44  				return nil, errors.New("agent's tag is not a machine tag")
    45  			}
    46  
    47  			// Get API connection.
    48  			var apiCaller base.APICaller
    49  			if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    50  				return nil, err
    51  			}
    52  			apiState := apiagent.NewState(apiCaller)
    53  
    54  			// If the machine needs State, grab the state serving info
    55  			// over the API and write it to the agent configuration.
    56  			machine, err := apiState.Entity(tag)
    57  			if err != nil {
    58  				return nil, err
    59  			}
    60  			for _, job := range machine.Jobs() {
    61  				if job.NeedsState() {
    62  					info, err := apiState.StateServingInfo()
    63  					if err != nil {
    64  						return nil, errors.Errorf("cannot get state serving info: %v", err)
    65  					}
    66  					err = agent.ChangeConfig(func(config coreagent.ConfigSetter) error {
    67  						config.SetStateServingInfo(info)
    68  						return nil
    69  					})
    70  					if err != nil {
    71  						return nil, err
    72  					}
    73  				}
    74  			}
    75  
    76  			// All is well - we're done (no actual worker is actually returned).
    77  			return nil, dependency.ErrUninstall
    78  		},
    79  	}
    80  }