Get Stats For IMDSV2 Fallback Succeed (#838)

handlers/agentinfo/info.go

@@ -49,6 +49,7 @@ var (
 	fullVersion             = getFullVersion(version)
 	id                      = uuid.NewString()
 	sharedConfigFallback    atomic.Bool
+	imdsFallbackSucceed     atomic.Bool
 )
 
 var isRunningAsRoot = defaultIsRunningAsRoot
@@ -75,6 +76,7 @@ type agentStats struct {
 	PayloadBytes         *int     `json:"load,omitempty"`
 	StatusCode           *int     `json:"code,omitempty"`
 	SharedConfigFallback *int     `json:"scfb,omitempty"`
+	ImdsFallbackSucceed  *int     `json:"ifs,omitempty"`
 }
 
 func New(groupName string) AgentInfo {
@@ -123,6 +125,7 @@ func (ai *agentInfo) RecordOpData(latency time.Duration, payloadBytes int, err e
 		stats.FileDescriptorCount = ai.fileDescriptorCount()
 		stats.ThreadCount = ai.threadCount()
 		stats.SharedConfigFallback = getSharedConfigFallback()
+		stats.ImdsFallbackSucceed = succeedImdsFallback()
 		ai.nextUpdate = now.Add(updateInterval)
 	}
 
@@ -154,6 +157,15 @@ func (ai *agentInfo) fileDescriptorCount() *int32 {
 	return nil
 }
 
+// we only need to know if value is 1
+// thus return nil if not set
+func succeedImdsFallback() *int {
+	if imdsFallbackSucceed.Load() {
+		return aws.Int(1)
+	}
+	return nil
+}
+
 func (ai *agentInfo) threadCount() *int32 {
 	if thCount, err := ai.proc.NumThreads(); err == nil {
 		return aws.Int32(thCount)
@@ -286,6 +298,8 @@ func readVersionFile() string {
 	return strings.Trim(string(byteArray), " \n\r\t")
 }
 
+// this returns true for true or invalid
+// examples of invalid are not set env var, "", "invalid"
 func getUsageDataEnabled() bool {
 	ok, err := strconv.ParseBool(os.Getenv(envconfig.CWAGENT_USAGE_DATA))
 	return ok || err != nil
@@ -312,3 +326,7 @@ func getSharedConfigFallback() *int {
 	}
 	return nil
 }
+
+func SetImdsFallbackSucceed() {
+	imdsFallbackSucceed.Store(true)
+}

handlers/agentinfo/info_test.go

@@ -123,8 +123,12 @@ func TestGetAgentStats(t *testing.T) {
 		LatencyMillis:       aws.Int64(1234),
 		PayloadBytes:        aws.Int(5678),
 		StatusCode:          aws.Int(200),
+		ImdsFallbackSucceed: aws.Int(1),
 	}
 
+	assert.Equal(t, "\"cpu\":1.2,\"mem\":123,\"fd\":456,\"th\":789,\"lat\":1234,\"load\":5678,\"code\":200,\"ifs\":1", getAgentStats(stats))
+
+	stats.ImdsFallbackSucceed = nil
 	assert.Equal(t, "\"cpu\":1.2,\"mem\":123,\"fd\":456,\"th\":789,\"lat\":1234,\"load\":5678,\"code\":200", getAgentStats(stats))
 
 	stats.CpuPercent = nil
@@ -246,3 +250,12 @@ func TestSharedConfigFallback(t *testing.T) {
 	RecordSharedConfigFallback()
 	assert.Equal(t, 1, *(getSharedConfigFallback()))
 }
+
+func TestSetImdsFallbackSucceed(t *testing.T) {
+	defer imdsFallbackSucceed.Store(false)
+	assert.False(t, imdsFallbackSucceed.Load())
+	assert.Nil(t, succeedImdsFallback())
+	SetImdsFallbackSucceed()
+	assert.True(t, imdsFallbackSucceed.Load())
+	assert.Equal(t, aws.Int(1), succeedImdsFallback())
+}

plugins/processors/ec2tagger/ec2metadataprovider.go

@@ -12,6 +12,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/ec2metadata"
 
 	configaws "github.com/aws/amazon-cloudwatch-agent/cfg/aws"
+	"github.com/aws/amazon-cloudwatch-agent/handlers/agentinfo"
 	"github.com/aws/amazon-cloudwatch-agent/internal/retryer"
 )
 
@@ -49,7 +50,11 @@ func (c *metadataClient) InstanceID(ctx context.Context) (string, error) {
 	instanceId, err := c.metadataFallbackDisabled.GetMetadataWithContext(ctx, "instance-id")
 	if err != nil {
 		log.Printf("D! could not get instance id without imds v1 fallback enable thus enable fallback")
-		return c.metadataFallbackEnabled.GetMetadataWithContext(ctx, "instance-id")
+		instanceInner, errorInner := c.metadataFallbackEnabled.GetMetadataWithContext(ctx, "instance-id")
+		if errorInner == nil {
+			agentinfo.SetImdsFallbackSucceed()
+		}
+		return instanceInner, errorInner
 	}
 	return instanceId, err
 }
@@ -58,7 +63,11 @@ func (c *metadataClient) Hostname(ctx context.Context) (string, error) {
 	hostname, err := c.metadataFallbackDisabled.GetMetadataWithContext(ctx, "hostname")
 	if err != nil {
 		log.Printf("D! could not get hostname without imds v1 fallback enable thus enable fallback")
-		return c.metadataFallbackEnabled.GetMetadataWithContext(ctx, "hostname")
+		hostnameInner, errorInner := c.metadataFallbackEnabled.GetMetadataWithContext(ctx, "hostname")
+		if errorInner == nil {
+			agentinfo.SetImdsFallbackSucceed()
+		}
+		return hostnameInner, errorInner
 	}
 	return hostname, err
 }
@@ -67,7 +76,11 @@ func (c *metadataClient) Get(ctx context.Context) (ec2metadata.EC2InstanceIdenti
 	instanceDocument, err := c.metadataFallbackDisabled.GetInstanceIdentityDocumentWithContext(ctx)
 	if err != nil {
 		log.Printf("D! could not get instance document without imds v1 fallback enable thus enable fallback")
-		return c.metadataFallbackEnabled.GetInstanceIdentityDocumentWithContext(ctx)
+		instanceDocumentInner, errorInner := c.metadataFallbackEnabled.GetInstanceIdentityDocumentWithContext(ctx)
+		if errorInner == nil {
+			agentinfo.SetImdsFallbackSucceed()
+		}
+		return instanceDocumentInner, errorInner
 	}
 	return instanceDocument, err
 }

translator/util/ec2util/ec2util.go

@@ -15,6 +15,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/session"
 
 	configaws "github.com/aws/amazon-cloudwatch-agent/cfg/aws"
+	"github.com/aws/amazon-cloudwatch-agent/handlers/agentinfo"
 	"github.com/aws/amazon-cloudwatch-agent/internal/retryer"
 	"github.com/aws/amazon-cloudwatch-agent/translator/config"
 	"github.com/aws/amazon-cloudwatch-agent/translator/context"
@@ -116,6 +117,7 @@ func (e *ec2Util) deriveEC2MetadataFromIMDS() error {
 		hostnameInner, errInner := mdEnableFallback.GetMetadata("hostname")
 		if errInner == nil {
 			e.Hostname = hostnameInner
+			agentinfo.SetImdsFallbackSucceed()
 		} else {
 			fmt.Println("E! [EC2] Fetch hostname from EC2 metadata fail:", errInner)
 		}
@@ -135,6 +137,7 @@ func (e *ec2Util) deriveEC2MetadataFromIMDS() error {
 			e.AccountID = instanceIdentityDocumentInner.AccountID
 			e.PrivateIP = instanceIdentityDocumentInner.PrivateIP
 			e.InstanceID = instanceIdentityDocumentInner.InstanceID
+			agentinfo.SetImdsFallbackSucceed()
 		} else {
 			fmt.Println("E! [EC2] Fetch identity document from EC2 metadata fail:", errInner)
 		}