Fix DescribeTags retry on high-frequency and delay refresh interval

extension/entitystore/serviceprovider.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/arn"
+	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/aws/aws-sdk-go/service/ec2/ec2iface"
 
@@ -39,8 +40,13 @@ const (
 	ServiceNameSourceUnknown           = "Unknown"
 	ServiceNameSourceUserConfiguration = "UserConfiguration"
 
-	jitterMax = 180
-	jitterMin = 60
+	describeTagsJitterMax = 3600
+	describeTagsJitterMin = 3000
+	defaultJitterMin      = 60
+	defaultJitterMax      = 180
+	maxRetry              = 3
+	infRetry              = -1
+	RequestLimitExceeded  = "RequestLimitExceeded"
 )
 
 var (
@@ -86,10 +92,10 @@ type serviceprovider struct {
 func (s *serviceprovider) startServiceProvider() {
 	err := s.getEC2Client()
 	if err != nil {
-		go refreshLoop(s.done, s.getEC2Client, true)
+		go refreshLoop(s.done, s.getEC2Client, true, "", defaultJitterMin, defaultJitterMax, ec2tagger.BackoffSleepArray, infRetry)
 	}
-	go refreshLoop(s.done, s.getIAMRole, false)
-	go refreshLoop(s.done, s.getEC2TagServiceName, false)
+	go refreshLoop(s.done, s.getIAMRole, false, "", defaultJitterMin, defaultJitterMax, ec2tagger.BackoffSleepArray, infRetry)
+	go refreshLoop(s.done, s.getEC2TagServiceName, false, RequestLimitExceeded, describeTagsJitterMin, describeTagsJitterMax, ec2tagger.ThrottleBackOffArray, maxRetry)
 }
 
 // addEntryForLogFile adds an association between a log file glob and a service attribute, as configured in the
@@ -242,7 +248,7 @@ func (s *serviceprovider) getEC2TagServiceName() error {
 		}
 		result, err := s.ec2API.DescribeTags(input)
 		if err != nil {
-			continue
+			return err
 		}
 		for _, tag := range result.Tags {
 			key := *tag.Key
@@ -307,23 +313,28 @@ func newServiceProvider(mode string, region string, ec2Info *ec2Info, metadataPr
 	}
 }
 
-func refreshLoop(done chan struct{}, updateFunc func() error, oneTime bool) {
+func refreshLoop(done chan struct{}, updateFunc func() error, oneTime bool, retryOnError string, successRetryMin int, successRetryMax int, backoffArray []time.Duration, maxRetry int) int {
 	// Offset retry by 1 so we can start with 1 minute wait time
 	// instead of immediately retrying
 	retry := 1
 	for {
+		if maxRetry != -1 && retry > maxRetry {
+			return retry
+		}
 		err := updateFunc()
 		if err == nil && oneTime {
-			return
+			return retry
+		} else if awsErr, ok := err.(awserr.Error); ok && retryOnError != "" && awsErr.Code() != retryOnError {
+			return retry
 		}
 
-		waitDuration := calculateWaitTime(retry, err)
+		waitDuration := calculateWaitTime(retry-1, err, successRetryMin, successRetryMax, backoffArray)
 		wait := time.NewTimer(waitDuration)
 		select {
 		case <-done:
 			log.Printf("D! serviceprovider: Shutting down now")
 			wait.Stop()
-			return
+			return retry
 		case <-wait.C:
 		}
 
@@ -339,20 +350,21 @@ func refreshLoop(done chan struct{}, updateFunc func() error, oneTime bool) {
 		}
 
 	}
+	return retry
 }
 
 // calculateWaitTime returns different time based on whether if
 // a function call was returned with error. If returned with error,
 // follow exponential backoff wait time, otherwise, refresh with jitter
-func calculateWaitTime(retry int, err error) time.Duration {
+func calculateWaitTime(retry int, err error, successRetryMin int, successRetryMax int, backoffArray []time.Duration) time.Duration {
 	var waitDuration time.Duration
 	if err == nil {
-		return time.Duration(rand.Intn(jitterMax-jitterMin)+jitterMin) * time.Second
+		return time.Duration(rand.Intn(successRetryMax-successRetryMin)+successRetryMin) * time.Second
 	}
-	if retry < len(ec2tagger.BackoffSleepArray) {
-		waitDuration = ec2tagger.BackoffSleepArray[retry]
+	if retry < len(backoffArray) {
+		waitDuration = backoffArray[retry]
 	} else {
-		waitDuration = ec2tagger.BackoffSleepArray[len(ec2tagger.BackoffSleepArray)-1]
+		waitDuration = backoffArray[len(backoffArray)-1]
 	}
 	return waitDuration
 }

extension/entitystore/serviceprovider_test.go

@@ -8,28 +8,40 @@ import (
 	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/aws/aws-sdk-go/aws/ec2metadata"
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/aws/aws-sdk-go/service/ec2/ec2iface"
 	"github.com/stretchr/testify/assert"
 
 	configaws "github.com/aws/amazon-cloudwatch-agent/cfg/aws"
 	"github.com/aws/amazon-cloudwatch-agent/internal/ec2metadataprovider"
+	"github.com/aws/amazon-cloudwatch-agent/plugins/processors/ec2tagger"
 	"github.com/aws/amazon-cloudwatch-agent/translator/config"
 )
 
 type mockServiceNameEC2Client struct {
 	ec2iface.EC2API
+	throttleError bool
+	authError     bool
 }
 
 // construct the return results for the mocked DescribeTags api
 var (
 	tagKeyService = "service"
 	tagValService = "test-service"
 	tagDesService = ec2.TagDescription{Key: &tagKeyService, Value: &tagValService}
+
+	FastBackOffArray = []time.Duration{0, 0, 0}
 )
 
 func (m *mockServiceNameEC2Client) DescribeTags(*ec2.DescribeTagsInput) (*ec2.DescribeTagsOutput, error) {
+	if m.throttleError {
+		return nil, awserr.New(RequestLimitExceeded, "throttle limit exceeded", nil)
+	}
+	if m.authError {
+		return nil, awserr.New("UnauthorizedOperation", "UnauthorizedOperation occurred", nil)
+	}
 	testTags := ec2.DescribeTagsOutput{
 		NextToken: nil,
 		Tags:      []*ec2.TagDescription{&tagDesService},
@@ -365,7 +377,6 @@ func Test_refreshLoop(t *testing.T) {
 		ec2API            ec2iface.EC2API
 		iamRole           string
 		ec2TagServiceName string
-		refreshInterval   time.Duration
 		oneTime           bool
 	}
 	type expectedInfo struct {
@@ -387,7 +398,6 @@ func Test_refreshLoop(t *testing.T) {
 				ec2API:            &mockServiceNameEC2Client{},
 				iamRole:           "original-role",
 				ec2TagServiceName: "original-tag-name",
-				refreshInterval:   time.Millisecond,
 			},
 			expectedInfo: expectedInfo{
 				iamRole:           "TestRole",
@@ -408,12 +418,69 @@ func Test_refreshLoop(t *testing.T) {
 				ec2TagServiceName: tt.fields.ec2TagServiceName,
 				done:              done,
 			}
-			go refreshLoop(done, s.getEC2TagServiceName, tt.fields.oneTime)
-			go refreshLoop(done, s.getIAMRole, tt.fields.oneTime)
+			go refreshLoop(done, s.getEC2TagServiceName, tt.fields.oneTime, RequestLimitExceeded, describeTagsJitterMin, describeTagsJitterMax, ec2tagger.ThrottleBackOffArray, maxRetry)
+			go refreshLoop(done, s.getIAMRole, tt.fields.oneTime, "", defaultJitterMin, defaultJitterMax, ec2tagger.BackoffSleepArray, infRetry)
 			time.Sleep(time.Second)
 			close(done)
 			assert.Equal(t, tt.expectedInfo.iamRole, s.iamRole)
 			assert.Equal(t, tt.expectedInfo.ec2TagServiceName, s.ec2TagServiceName)
 		})
 	}
 }
+
+func Test_refreshLoopRetry(t *testing.T) {
+	type fields struct {
+		metadataProvider ec2metadataprovider.MetadataProvider
+		ec2API           ec2iface.EC2API
+		oneTime          bool
+	}
+	tests := []struct {
+		name          string
+		fields        fields
+		expectedRetry int
+	}{
+		{
+			name: "ThrottleLimitError",
+			fields: fields{
+				metadataProvider: &mockMetadataProvider{
+					InstanceIdentityDocument: &ec2metadata.EC2InstanceIdentityDocument{
+						InstanceID: "i-123456789"},
+				},
+				ec2API: &mockServiceNameEC2Client{
+					throttleError: true,
+				},
+			},
+			expectedRetry: 4,
+		},
+		{
+			name: "AuthError",
+			fields: fields{
+				metadataProvider: &mockMetadataProvider{
+					InstanceIdentityDocument: &ec2metadata.EC2InstanceIdentityDocument{
+						InstanceID: "i-123456789"},
+				},
+				ec2API: &mockServiceNameEC2Client{
+					authError: true,
+				},
+			},
+			expectedRetry: 1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			done := make(chan struct{})
+			s := &serviceprovider{
+				metadataProvider: tt.fields.metadataProvider,
+				ec2API:           tt.fields.ec2API,
+				ec2Provider: func(s string, config *configaws.CredentialConfig) ec2iface.EC2API {
+					return tt.fields.ec2API
+				},
+				done: done,
+			}
+			retry := refreshLoop(done, s.getEC2TagServiceName, tt.fields.oneTime, RequestLimitExceeded, describeTagsJitterMin, describeTagsJitterMax, FastBackOffArray, maxRetry)
+			time.Sleep(time.Second)
+			close(done)
+			assert.Equal(t, tt.expectedRetry, retry)
+		})
+	}
+}

plugins/processors/ec2tagger/constants.go

@@ -70,5 +70,6 @@ const (
 var (
 	// issue with newer versions of the sdk take longer when hop limit is 1 in eks
 	defaultRefreshInterval = 180 * time.Second
+	ThrottleBackOffArray   = []time.Duration{0, 1 * time.Minute, 3 * time.Minute}                                                                      // backoff retry for ec2 describe instances API call. Assuming the throttle limit is 20 per second. 10 mins allow 12000 API calls.
 	BackoffSleepArray      = []time.Duration{0, 1 * time.Minute, 1 * time.Minute, 3 * time.Minute, 3 * time.Minute, 3 * time.Minute, 10 * time.Minute} // backoff retry for ec2 describe instances API call. Assuming the throttle limit is 20 per second. 10 mins allow 12000 API calls.
 )