Add support for latency metrics

ecs-agent/acs/session/session.go

@@ -251,7 +251,6 @@ func (s *session) startSessionOnce(ctx context.Context) error {
 		})
 		return err
 	}
-	s.metricsFactory.New(metrics.DiscoverPollEndpointDurationName).WithGauge(s.ecsClient.GetDiscoverPollEndpointDuration()).Done(nil)
 
 	client := s.clientFactory.New(
 		s.acsURL(acsEndpoint),

ecs-agent/api/ecs/client/ecs_client.go

@@ -39,6 +39,7 @@ import (
 	"github.com/aws/amazon-ecs-agent/ecs-agent/httpclient"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/logger"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/logger/field"
+	"github.com/aws/amazon-ecs-agent/ecs-agent/metrics"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/utils"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/utils/retry"
 )
@@ -77,7 +78,7 @@ type ecsClient struct {
 	shouldExcludeIPv6PortBinding     bool
 	sascCustomRetryBackoff           func(func() error) error
 	stscAttachmentCustomRetryBackoff func(func() error) error
-	discoverPollEndpointDuration     time.Duration
+	metricsFactory                   metrics.EntryFactory
 }
 
 // NewECSClient creates a new ECSClient interface object.
@@ -113,6 +114,9 @@ func NewECSClient(
 	if client.submitStateChangeClient == nil {
 		client.submitStateChangeClient = newSubmitStateChangeClient(&ecsConfig)
 	}
+	if client.metricsFactory == nil {
+		client.metricsFactory = metrics.NewNopEntryFactory()
+	}
 
 	return client, nil
 }
@@ -778,7 +782,7 @@ func (client *ecsClient) discoverPollEndpoint(containerInstanceArn string,
 		return nil, err
 	}
 
-	client.discoverPollEndpointDuration = time.Since(discoverPollEndpointStartTime)
+	client.metricsFactory.New(metrics.DiscoverPollEndpointDurationName).WithGauge(time.Since(discoverPollEndpointStartTime)).Done(nil)
 	// Cache the response from ECS.
 	client.pollEndpointCache.Set(containerInstanceArn, output)
 	return output, nil
@@ -872,7 +876,3 @@ func trimString(inputString string, maxLen int) string {
 		return inputString
 	}
 }
-
-func (client *ecsClient) GetDiscoverPollEndpointDuration() time.Duration {
-	return client.discoverPollEndpointDuration
-}

ecs-agent/api/ecs/client/ecs_client_option.go

@@ -16,6 +16,7 @@ package ecsclient
 import (
 	"github.com/aws/amazon-ecs-agent/ecs-agent/api/ecs"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/async"
+	"github.com/aws/amazon-ecs-agent/ecs-agent/metrics"
 )
 
 // ECSClientOption allows for configuration of an ecsClient.
@@ -87,3 +88,12 @@ func WithSubmitStateChangeClient(s ecs.ECSSubmitStateSDK) ECSClientOption {
 		client.submitStateChangeClient = s
 	}
 }
+
+// WithMetricsFactory is an ECSClientOption that configures
+// ecsClient.metricsFactory with the value passed as a parameter.
+// This is especially useful for emitting metrics in the ECS Client
+func WithMetricsFactory(metricsFactory metrics.EntryFactory) ECSClientOption {
+	return func(client *ecsClient) {
+		client.metricsFactory = metricsFactory
+	}
+}

ecs-agent/api/ecs/client/ecs_client_option_test.go

@@ -22,6 +22,7 @@ import (
 
 	mock_ecs "github.com/aws/amazon-ecs-agent/ecs-agent/api/ecs/mocks"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/async"
+	"github.com/aws/amazon-ecs-agent/ecs-agent/metrics"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -102,3 +103,10 @@ func TestWithSubmitStateChangeClient(t *testing.T) {
 	option(client)
 	assert.Equal(t, newSubmitStateChangeClient, client.submitStateChangeClient)
 }
+
+func TestWithMetricsFactory(t *testing.T) {
+	client := &ecsClient{} // client.metricsFactory is nil by default
+	option := WithMetricsFactory(metrics.NewNopEntryFactory())
+	option(client)
+	assert.NotNil(t, client.metricsFactory)
+}

ecs-agent/api/ecs/interface.go

@@ -14,8 +14,6 @@
 package ecs
 
 import (
-	"time"
-
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/request"
 
@@ -64,8 +62,6 @@ type ECSClient interface {
 	UpdateContainerInstancesState(instanceARN, status string) error
 	// GetHostResources retrieves a map that map the resource name to the corresponding resource
 	GetHostResources() (map[string]*ecs.Resource, error)
-	// GetDiscoverPollEndpointDuration retrieves the time it takes for the DiscoverPollEndpoint call
-	GetDiscoverPollEndpointDuration() time.Duration
 }
 
 // ECSSDK is an interface that specifies the subset of the AWS Go SDK's ECS