resources: aws: ec2: Add method to make sns topic

resources/aws_ec2.go

@@ -33,6 +33,8 @@ import (
 	"github.com/aws/aws-sdk-go/aws/request"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/aws/aws-sdk-go/service/sns"
+	multierr "github.com/hashicorp/go-multierror"
 	errwrap "github.com/pkg/errors"
 )
 
@@ -44,6 +46,12 @@ const (
 	// AwsPrefix is a const which gets prepended onto object names. We can only use
 	// alphanumeric chars, underscores and hyphens for sns topics and cloud watch rules.
 	AwsPrefix = "_mgmt-"
+	// Ec2Prefix is added to the names of sns and cloudwatch objects.
+	Ec2Prefix = AwsPrefix + "ec2-"
+	// SnsPrefix gets prepended onto the sns topic.
+	SnsPrefix = Ec2Prefix + "sns-"
+	// SnsTopicName is the name of the sns topic created by snsMakeTopic.
+	SnsTopicName = SnsPrefix + "events"
 	// waitTimeout is the duration in seconds of the timeout context in CheckApply.
 	waitTimeout = 400
 )
@@ -88,6 +96,11 @@ type AwsEc2Res struct {
 
 	client *ec2.EC2 // client session for AWS API calls
 
+	snsClient *sns.SNS // client for AWS SNS API calls
+	// snsTopicArn requires looping through every topic to get,
+	// so we save it here when we create the topic instead.
+	snsTopicArn string
+
 	awsChan   chan *chanStruct // channel used to send events and errors to Watch()
 	closeChan chan struct{}    // channel used to cancel context when it's time to shut down
 	wg        *sync.WaitGroup  // waitgroup for goroutines in Watch()
@@ -175,6 +188,25 @@ func (obj *AwsEc2Res) Init() error {
 	obj.closeChan = make(chan struct{})
 	obj.wg = &sync.WaitGroup{}
 
+	// if we are using sns watch
+	if obj.WatchListenAddr != "" {
+		// make sns client
+		snsSess, err := session.NewSession(&aws.Config{
+			Region: aws.String(obj.Region),
+		})
+		if err != nil {
+			return errwrap.Wrapf(err, "error creating sns session")
+		}
+		obj.snsClient = sns.New(snsSess)
+		// make the sns topic
+		snsTopicArn, err := obj.snsMakeTopic()
+		if err != nil {
+			return errwrap.Wrapf(err, "error making sns topic")
+		}
+		// save the topicArn for later use
+		obj.snsTopicArn = snsTopicArn
+	}
+
 	return obj.BaseRes.Init() // call base init, b/c we're overriding
 }
 
@@ -656,6 +688,9 @@ func (obj *AwsEc2Res) Compare(r Res) bool {
 	if obj.UserData != res.UserData {
 		return false
 	}
+	if obj.WatchListenAddr != res.WatchListenAddr {
+		return false
+	}
 	return true
 }
 
@@ -708,3 +743,50 @@ func (obj *AwsEc2Res) snsPostHandler(w http.ResponseWriter, req *http.Request) {
 		log.Printf("%s: Post: %s", obj, string(post))
 	}
 }
+
+// snsMakeTopic creates a topic on aws sns.
+func (obj *AwsEc2Res) snsMakeTopic() (string, error) {
+	// make topic
+	topicInput := &sns.CreateTopicInput{
+		Name: aws.String(SnsTopicName),
+	}
+	topic, err := obj.snsClient.CreateTopic(topicInput)
+	if err != nil {
+		return "", err
+	}
+	log.Printf("%s: Created SNS Topic", obj)
+	if topic.TopicArn == nil {
+		return "", fmt.Errorf("TopicArn is nil")
+	}
+	return *topic.TopicArn, nil
+}
+
+// snsDeleteTopic deletes the sns topic.
+func (obj *AwsEc2Res) snsDeleteTopic(topicArn string) error {
+	// delete the topic
+	dtInput := &sns.DeleteTopicInput{
+		TopicArn: aws.String(topicArn),
+	}
+	if _, err := obj.snsClient.DeleteTopic(dtInput); err != nil {
+		return err
+	}
+	log.Printf("%s: Deleted SNS Topic", obj)
+	return nil
+}
+
+// Close cleans up when we're done. This is needed to delete some of the AWS
+// objects created for the SNS endpoint.
+func (obj *AwsEc2Res) Close() error {
+	var errList error
+	// clean up sns objects created by Init/snsWatch
+	if obj.snsClient != nil {
+		// delete the topic
+		if err := obj.snsDeleteTopic(obj.snsTopicArn); err != nil {
+			errList = multierr.Append(errList, err)
+		}
+	}
+	if err := obj.BaseRes.Close(); err != nil {
+		errList = multierr.Append(errList, err) // list of errors
+	}
+	return errList
+}