github.com/jerryclinesmith/packer@v0.3.7/builder/amazon/common/instance.go (about) 1 package common 2 3 import ( 4 "errors" 5 "fmt" 6 "github.com/mitchellh/goamz/ec2" 7 "github.com/mitchellh/multistep" 8 "log" 9 "time" 10 ) 11 12 // StateRefreshFunc is a function type used for StateChangeConf that is 13 // responsible for refreshing the item being watched for a state change. 14 // 15 // It returns three results. `result` is any object that will be returned 16 // as the final object after waiting for state change. This allows you to 17 // return the final updated object, for example an EC2 instance after refreshing 18 // it. 19 // 20 // `state` is the latest state of that object. And `err` is any error that 21 // may have happened while refreshing the state. 22 type StateRefreshFunc func() (result interface{}, state string, err error) 23 24 // StateChangeConf is the configuration struct used for `WaitForState`. 25 type StateChangeConf struct { 26 Conn *ec2.EC2 27 Pending []string 28 Refresh StateRefreshFunc 29 StepState multistep.StateBag 30 Target string 31 } 32 33 // InstanceStateRefreshFunc returns a StateRefreshFunc that is used to watch 34 // an EC2 instance. 35 func InstanceStateRefreshFunc(conn *ec2.EC2, i *ec2.Instance) StateRefreshFunc { 36 return func() (interface{}, string, error) { 37 resp, err := conn.Instances([]string{i.InstanceId}, ec2.NewFilter()) 38 if err != nil { 39 log.Printf("Error on InstanceStateRefresh: %s", err) 40 return nil, "", err 41 } 42 43 if len(resp.Reservations) == 0 || len(resp.Reservations[0].Instances) == 0 { 44 // Sometimes AWS just has consistency issues and doesn't see 45 // our instance yet. Return an empty state. 46 return nil, "", nil 47 } 48 49 i = &resp.Reservations[0].Instances[0] 50 return i, i.State.Name, nil 51 } 52 } 53 54 // WaitForState watches an object and waits for it to achieve a certain 55 // state. 56 func WaitForState(conf *StateChangeConf) (i interface{}, err error) { 57 log.Printf("Waiting for state to become: %s", conf.Target) 58 59 for { 60 var currentState string 61 i, currentState, err = conf.Refresh() 62 if err != nil { 63 return 64 } 65 66 // Check states only if we were able to refresh to an instance 67 // that exists. 68 if i != nil { 69 if currentState == conf.Target { 70 return 71 } 72 73 if conf.StepState != nil { 74 if _, ok := conf.StepState.GetOk(multistep.StateCancelled); ok { 75 return nil, errors.New("interrupted") 76 } 77 } 78 79 found := false 80 for _, allowed := range conf.Pending { 81 if currentState == allowed { 82 found = true 83 break 84 } 85 } 86 87 if !found { 88 fmt.Errorf("unexpected state '%s', wanted target '%s'", currentState, conf.Target) 89 return 90 } 91 } 92 93 time.Sleep(2 * time.Second) 94 } 95 96 return 97 }