105 lines
2.7 KiB
Go
105 lines
2.7 KiB
Go
package aws
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import (
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"errors"
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"fmt"
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"log"
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"time"
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"github.com/mitchellh/goamz/ec2"
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)
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// StateRefreshFunc is a function type used for StateChangeConf that is
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// responsible for refreshing the item being watched for a state change.
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//
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// It returns three results. `result` is any object that will be returned
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// as the final object after waiting for state change. This allows you to
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// return the final updated object, for example an EC2 instance after refreshing
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// it.
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//
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// `state` is the latest state of that object. And `err` is any error that
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// may have happened while refreshing the state.
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type StateRefreshFunc func() (result interface{}, state string, err error)
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// StateChangeConf is the configuration struct used for `WaitForState`.
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type StateChangeConf struct {
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Pending []string
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Refresh StateRefreshFunc
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Target string
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}
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// InstanceStateRefreshFunc returns a StateRefreshFunc that is used to watch
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// an EC2 instance.
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func InstanceStateRefreshFunc(conn *ec2.EC2, i *ec2.Instance) StateRefreshFunc {
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return func() (interface{}, string, error) {
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resp, err := conn.Instances([]string{i.InstanceId}, ec2.NewFilter())
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if err != nil {
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if ec2err, ok := err.(*ec2.Error); ok && ec2err.Code == "InvalidInstanceID.NotFound" {
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// Set this to nil as if we didn't find anything.
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resp = nil
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} else {
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log.Printf("Error on InstanceStateRefresh: %s", err)
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return nil, "", err
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}
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}
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if resp == nil || len(resp.Reservations) == 0 || len(resp.Reservations[0].Instances) == 0 {
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// Sometimes AWS just has consistency issues and doesn't see
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// our instance yet. Return an empty state.
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return nil, "", nil
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}
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i = &resp.Reservations[0].Instances[0]
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return i, i.State.Name, nil
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}
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}
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// WaitForState watches an object and waits for it to achieve a certain
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// state.
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func WaitForState(conf *StateChangeConf) (i interface{}, err error) {
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log.Printf("Waiting for state to become: %s", conf.Target)
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notfoundTick := 0
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for {
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var currentState string
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i, currentState, err = conf.Refresh()
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if err != nil {
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return
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}
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if i == nil {
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// If we didn't find the resource, check if we have been
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// not finding it for awhile, and if so, report an error.
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notfoundTick += 1
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if notfoundTick > 20 {
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return nil, errors.New("couldn't find resource")
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}
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} else {
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// Reset the counter for when a resource isn't found
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notfoundTick = 0
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if currentState == conf.Target {
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return
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}
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found := false
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for _, allowed := range conf.Pending {
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if currentState == allowed {
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found = true
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break
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}
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}
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if !found {
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fmt.Errorf("unexpected state '%s', wanted target '%s'", currentState, conf.Target)
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return
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}
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}
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time.Sleep(2 * time.Second)
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}
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return
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}
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