Add v3 metadata support to ecs input (influxdata#7154)

plugins/inputs/ecs/README.md

@@ -1,8 +1,8 @@
 # Amazon ECS Input Plugin
 
-Amazon ECS, Fargate compatible, input plugin which uses the [Amazon ECS v2 metadata and
-stats API][task-metadata-endpoint-v2] endpoints to gather stats on running
-containers in a Task.
+Amazon ECS, Fargate compatible, input plugin which uses the Amazon ECS metadata and
+stats [v2][task-metadata-endpoint-v2] or [v3][task-metadata-endpoint-v3] API endpoints
+to gather stats on running containers in a Task.
 
 The telegraf container must be run in the same Task as the workload it is
 inspecting.
@@ -19,8 +19,41 @@ present in the metadata/stats endpoints.
 ```toml
 # Read metrics about ECS containers
 [[inputs.ecs]]
-  ## ECS metadata url
-  # endpoint_url = "http://169.254.170.2"
+  ## ECS metadata url.
+  ## Metadata v2 API is used if set explicitly. Otherwise,
+  ## v3 metadata endpoint API is used if available.
+  # endpoint_url = ""
+
+  ## Containers to include and exclude. Globs accepted.
+  ## Note that an empty array for both will include all containers
+  # container_name_include = []
+  # container_name_exclude = []
+
+  ## Container states to include and exclude. Globs accepted.
+  ## When empty only containers in the "RUNNING" state will be captured.
+  ## Possible values are "NONE", "PULLED", "CREATED", "RUNNING",
+  ## "RESOURCES_PROVISIONED", "STOPPED".
+  # container_status_include = []
+  # container_status_exclude = []
+
+  ## ecs labels to include and exclude as tags.  Globs accepted.
+  ## Note that an empty array for both will include all labels as tags
+  ecs_label_include = [ "com.amazonaws.ecs.*" ]
+  ecs_label_exclude = []
+
+  ## Timeout for queries.
+  # timeout = "5s"
+```
+
+### Configuration (enforce v2 metadata)
+
+```toml
+# Read metrics about ECS containers
+[[inputs.ecs]]
+  ## ECS metadata url.
+  ## Metadata v2 API is used if set explicitly. Otherwise,
+  ## v3 metadata endpoint API is used if available.
+  endpoint_url = "http://169.254.170.2"
 
   ## Containers to include and exclude. Globs accepted.
   ## Note that an empty array for both will include all containers
@@ -210,3 +243,4 @@ ecs_container_meta,cluster=test,com.amazonaws.ecs.cluster=test,com.amazonaws.ecs
 
 [docker-input]: /plugins/inputs/docker/README.md
 [task-metadata-endpoint-v2]: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v2.html
+[task-metadata-endpoint-v3] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v3.html

plugins/inputs/ecs/client.go

@@ -12,8 +12,13 @@ import (
 )
 
 var (
-	ecsMetadataPath, _  = url.Parse("/v2/metadata")
-	ecsMetaStatsPath, _ = url.Parse("/v2/stats")
+	// https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v2.html
+	ecsMetadataPath  = "/v2/metadata"
+	ecsMetaStatsPath = "/v2/stats"
+
+	// https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v3.html
+	ecsMetadataPathV3  = "/task"
+	ecsMetaStatsPathV3 = "/task/stats"
 )
 
 // Client is the ECS client contract
@@ -27,30 +32,78 @@ type httpClient interface {
 }
 
 // NewClient constructs an ECS client with the passed configuration params
-func NewClient(timeout time.Duration) (*EcsClient, error) {
+func NewClient(timeout time.Duration, endpoint string, version int) (*EcsClient, error) {
+	if version != 2 && version != 3 {
+		const msg = "expected metadata version 2 or 3, got %d"
+		return nil, fmt.Errorf(msg, version)
+	}
+
+	baseURL, err := url.Parse(endpoint)
+	if err != nil {
+		return nil, err
+	}
+
 	c := &http.Client{
 		Timeout: timeout,
 	}
 
 	return &EcsClient{
-		client: c,
+		client:   c,
+		baseURL:  baseURL,
+		taskURL:  resolveTaskURL(baseURL, version),
+		statsURL: resolveStatsURL(baseURL, version),
+		version:  version,
 	}, nil
 }
 
+func resolveTaskURL(base *url.URL, version int) string {
+	var path string
+	switch version {
+	case 2:
+		path = ecsMetadataPath
+	case 3:
+		path = ecsMetadataPathV3
+	default:
+		// Should never happen.
+		const msg = "resolveTaskURL: unexpected version %d"
+		panic(fmt.Errorf(msg, version))
+	}
+	return resolveURL(base, path)
+}
+
+func resolveStatsURL(base *url.URL, version int) string {
+	var path string
+	switch version {
+	case 2:
+		path = ecsMetaStatsPath
+	case 3:
+		path = ecsMetaStatsPathV3
+	default:
+		// Should never happen.
+		const msg = "resolveStatsURL: unexpected version %d"
+		panic(fmt.Errorf(msg, version))
+	}
+	return resolveURL(base, path)
+}
+
+// resolveURL returns a URL string by concatenating the string representation of base
+// and path. This is consistent with AWS metadata documentation:
+// https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v3.html#task-metadata-endpoint-v3-paths
+func resolveURL(base *url.URL, path string) string {
+	return base.String() + path
+}
+
 // EcsClient contains ECS connection config
 type EcsClient struct {
 	client   httpClient
-	BaseURL  *url.URL
+	version  int
+	baseURL  *url.URL
 	taskURL  string
 	statsURL string
 }
 
 // Task calls the ECS metadata endpoint and returns a populated Task
 func (c *EcsClient) Task() (*Task, error) {
-	if c.taskURL == "" {
-		c.taskURL = c.BaseURL.ResolveReference(ecsMetadataPath).String()
-	}
-
 	req, _ := http.NewRequest("GET", c.taskURL, nil)
 	resp, err := c.client.Do(req)
 	if err != nil {
@@ -74,10 +127,6 @@ func (c *EcsClient) Task() (*Task, error) {
 
 // ContainerStats calls the ECS stats endpoint and returns a populated container stats map
 func (c *EcsClient) ContainerStats() (map[string]types.StatsJSON, error) {
-	if c.statsURL == "" {
-		c.statsURL = c.BaseURL.ResolveReference(ecsMetaStatsPath).String()
-	}
-
 	req, _ := http.NewRequest("GET", c.statsURL, nil)
 	resp, err := c.client.Do(req)
 	if err != nil {

plugins/inputs/ecs/client_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 	"os"
 	"testing"
 
@@ -238,3 +239,77 @@ func TestEcsClient_ContainerStats(t *testing.T) {
 		})
 	}
 }
+
+func TestResolveTaskURL(t *testing.T) {
+	tests := []struct {
+		name string
+		base string
+		ver  int
+		exp  string
+	}{
+		{
+			name: "default v2 endpoint",
+			base: v2Endpoint,
+			ver:  2,
+			exp:  "http://169.254.170.2/v2/metadata",
+		},
+		{
+			name: "custom v2 endpoint",
+			base: "http://192.168.0.1",
+			ver:  2,
+			exp:  "http://192.168.0.1/v2/metadata",
+		},
+		{
+			name: "theoretical v3 endpoint",
+			base: "http://169.254.170.2/v3/metadata",
+			ver:  3,
+			exp:  "http://169.254.170.2/v3/metadata/task",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			baseURL, err := url.Parse(tt.base)
+			assert.NoError(t, err)
+
+			act := resolveTaskURL(baseURL, tt.ver)
+			assert.Equal(t, tt.exp, act)
+		})
+	}
+}
+
+func TestResolveStatsURL(t *testing.T) {
+	tests := []struct {
+		name string
+		base string
+		ver  int
+		exp  string
+	}{
+		{
+			name: "default v2 endpoint",
+			base: v2Endpoint,
+			ver:  2,
+			exp:  "http://169.254.170.2/v2/stats",
+		},
+		{
+			name: "custom v2 endpoint",
+			base: "http://192.168.0.1",
+			ver:  2,
+			exp:  "http://192.168.0.1/v2/stats",
+		},
+		{
+			name: "theoretical v3 endpoint",
+			base: "http://169.254.170.2/v3/metadata",
+			ver:  3,
+			exp:  "http://169.254.170.2/v3/metadata/task/stats",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			baseURL, err := url.Parse(tt.base)
+			assert.NoError(t, err)
+
+			act := resolveStatsURL(baseURL, tt.ver)
+			assert.Equal(t, tt.exp, act)
+		})
+	}
+}

plugins/inputs/ecs/ecs.go

@@ -1,7 +1,7 @@
 package ecs
 
 import (
-	"net/url"
+	"os"
 	"strings"
 	"time"
 
@@ -25,13 +25,14 @@ type Ecs struct {
 	LabelInclude []string `toml:"ecs_label_include"`
 	LabelExclude []string `toml:"ecs_label_exclude"`
 
-	newClient func(timeout time.Duration) (*EcsClient, error)
+	newClient func(timeout time.Duration, endpoint string, version int) (*EcsClient, error)
 
 	client              Client
 	filtersCreated      bool
 	labelFilter         filter.Filter
 	containerNameFilter filter.Filter
 	statusFilter        filter.Filter
+	metadataVersion     int
 }
 
 const (
@@ -40,11 +41,15 @@ const (
 	GB = 1000 * MB
 	TB = 1000 * GB
 	PB = 1000 * TB
+
+	v2Endpoint = "http://169.254.170.2"
 )
 
 var sampleConfig = `
-  ## ECS metadata url
-  # endpoint_url = "http://169.254.170.2"
+  ## ECS metadata url.
+  ## Metadata v2 API is used if set explicitly. Otherwise,
+  ## v3 metadata endpoint API is used if available.
+  # endpoint_url = ""
 
   ## Containers to include and exclude. Globs accepted.
   ## Note that an empty array for both will include all containers
@@ -69,7 +74,7 @@ var sampleConfig = `
 
 // Description describes ECS plugin
 func (ecs *Ecs) Description() string {
-	return "Read metrics about docker containers from Fargate/ECS v2 meta endpoints."
+	return "Read metrics about docker containers from Fargate/ECS v2, v3 meta endpoints."
 }
 
 // SampleConfig returns the ECS example config
@@ -107,18 +112,12 @@ func (ecs *Ecs) Gather(acc telegraf.Accumulator) error {
 
 func initSetup(ecs *Ecs) error {
 	if ecs.client == nil {
-		var err error
-		var c *EcsClient
-		c, err = ecs.newClient(ecs.Timeout.Duration)
-		if err != nil {
-			return err
-		}
+		resolveEndpoint(ecs)
 
-		c.BaseURL, err = url.Parse(ecs.EndpointURL)
+		c, err := ecs.newClient(ecs.Timeout.Duration, ecs.EndpointURL, ecs.metadataVersion)
 		if err != nil {
 			return err
 		}
-
 		ecs.client = c
 	}
 
@@ -142,6 +141,29 @@ func initSetup(ecs *Ecs) error {
 	return nil
 }
 
+func resolveEndpoint(ecs *Ecs) {
+	if ecs.EndpointURL != "" {
+		// Use metadata v2 API since endpoint is set explicitly.
+		ecs.metadataVersion = 2
+		return
+	}
+
+	// Auto-detect metadata endpoint version.
+
+	// Use metadata v3 if available.
+	// https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v3.html
+	v3Endpoint := os.Getenv("ECS_CONTAINER_METADATA_URI")
+	if v3Endpoint != "" {
+		ecs.EndpointURL = v3Endpoint
+		ecs.metadataVersion = 3
+		return
+	}
+
+	// Use v2 endpoint if nothing else is available.
+	ecs.EndpointURL = v2Endpoint
+	ecs.metadataVersion = 2
+}
+
 func (ecs *Ecs) accTask(task *Task, tags map[string]string, acc telegraf.Accumulator) {
 	taskFields := map[string]interface{}{
 		"revision":       task.Revision,
@@ -240,7 +262,7 @@ func (ecs *Ecs) createContainerStatusFilters() error {
 func init() {
 	inputs.Add("ecs", func() telegraf.Input {
 		return &Ecs{
-			EndpointURL:    "http://169.254.170.2",
+			EndpointURL:    "",
 			Timeout:        internal.Duration{Duration: 5 * time.Second},
 			newClient:      NewClient,
 			filtersCreated: false,