Add platform-specific default configs (#2212)

Author: jefchien

tool/downloader/downloader.go

@@ -105,7 +105,7 @@ func RunDownloader(mode, downloadLocation, outputDir, inputConfig, multiConfig s
 	case locationDefault:
 		if len(locationArray) == 2 {
 			name := locationArray[1]
-			cfg, ok := translatorconfig.DefaultJSONConfigFor(name)
+			cfg, ok := translatorconfig.DefaultJSONConfigFor(name, util.DetectKubernetesMode(mode) != "", util.DetectECS())
 			if !ok {
 				return fmt.Errorf("unknown default config %q", name)
 			}

tool/downloader/downloader_test.go

@@ -23,7 +23,7 @@ func TestRunDownloader_DefaultOtel(t *testing.T) {
 	content, err := os.ReadFile(filepath.Join(outputDir, "default_otel.tmp"))
 	require.NoError(t, err)
 
-	expected, ok := config.DefaultJSONConfigFor("otel")
+	expected, ok := config.DefaultJSONConfigFor("otel", false, false)
 	require.True(t, ok)
 	assert.JSONEq(t, expected, string(content))
 }

translator/cmdutil/translatorutil_test.go

@@ -439,7 +439,7 @@ func TestOpenTelemetryResourceAttributesSchemaValidation(t *testing.T) {
 }
 
 func TestDefaultOtelConfigSchemaValidation(t *testing.T) {
-	cfg, ok := config.DefaultJSONConfigFor("otel")
+	cfg, ok := config.DefaultJSONConfigFor("otel", false, false)
 	require.True(t, ok)
 	jsonMap, err := util.GetJsonMapFromJsonBytes([]byte(cfg))
 	require.NoError(t, err)

translator/config/defaultConfig.go

@@ -3,12 +3,59 @@
 
 package config
 
+import _ "embed"
+
+// Platform-specific default configs. Unlike otel.json/otel_windows.json (which
+// are OS-build-tagged), these have no OS constraint - K8s/ECS are Linux - so
+// they live here rather than in a build-tagged file.
+//
+//go:embed defaults/otel_ecs.json
+var defaultOtelECSConfig string
+
+//go:embed defaults/otel_k8s.json
+var defaultOtelK8sConfig string
+
+// otelConfigName is the shared map key for the otel default config and its
+// platform variants (e.g. -c default:otel).
+const otelConfigName = "otel"
+
+// defaultConfigs holds the base configs addressable by name.
 var defaultConfigs = map[string]string{
-	"otel": defaultOtelConfig,
+	otelConfigName: defaultOtelConfig,
 }
 
-// DefaultJSONConfigFor returns the named default config if it exists.
-func DefaultJSONConfigFor(name string) (string, bool) {
+// platform enumerates the environments that get a platform-specific default
+// config variant. VMs (EC2, Azure VM) use the base config; K8s and ECS get
+// their own variants since host-level scraping inside a container reports the
+// container, not the host.
+type platform int
+
+const (
+	platformK8s platform = iota
+	platformECS
+)
+
+// platformConfigs holds the platform variants. Kept out of defaultConfigs so
+// they are NOT addressable by name (e.g. -c default:otel_ecs on a VM).
+var platformConfigs = map[platform]map[string]string{
+	platformK8s: {otelConfigName: defaultOtelK8sConfig},
+	platformECS: {otelConfigName: defaultOtelECSConfig},
+}
+
+// DefaultJSONConfigFor returns the platform-specific variant when the caller's
+// detected platform has one, falling back to the named base config otherwise.
+// Kubernetes takes precedence over ECS.
+func DefaultJSONConfigFor(name string, isKubernetes, isECS bool) (string, bool) {
+	switch {
+	case isKubernetes:
+		if cfg, ok := platformConfigs[platformK8s][name]; ok {
+			return cfg, true
+		}
+	case isECS:
+		if cfg, ok := platformConfigs[platformECS][name]; ok {
+			return cfg, true
+		}
+	}
 	cfg, ok := defaultConfigs[name]
 	return cfg, ok
 }

translator/config/defaultConfig_test.go

@@ -11,17 +11,60 @@ import (
 )
 
 func TestDefaultJSONConfigFor_Otel(t *testing.T) {
-	cfg, ok := DefaultJSONConfigFor("otel")
+	cfg, ok := DefaultJSONConfigFor("otel", false, false)
 	require.True(t, ok)
 	assert.JSONEq(t, defaultOtelConfig, cfg)
 }
 
 func TestDefaultJSONConfigFor_Unknown(t *testing.T) {
-	_, ok := DefaultJSONConfigFor("unknown")
+	_, ok := DefaultJSONConfigFor("unknown", false, false)
 	assert.False(t, ok)
 }
 
 func TestDefaultJSONConfigFor_Empty(t *testing.T) {
-	_, ok := DefaultJSONConfigFor("")
+	_, ok := DefaultJSONConfigFor("", false, false)
+	assert.False(t, ok)
+}
+
+func TestDefaultJSONConfigFor_PlatformVariantsNotAddressableByName(t *testing.T) {
+	// The variant suffixes must not be resolvable as base config names, even
+	// when a platform is detected (e.g. -c default:otel_ecs on any host). The
+	// variants are only reachable via the platform flags on the base name.
+	_, ok := DefaultJSONConfigFor("otel_ecs", false, true)
+	assert.False(t, ok)
+	_, ok = DefaultJSONConfigFor("otel_k8s", true, false)
+	assert.False(t, ok)
+}
+
+func TestDefaultJSONConfigFor_OtelK8s(t *testing.T) {
+	cfg, ok := DefaultJSONConfigFor("otel", true, false)
+	require.True(t, ok)
+	assert.JSONEq(t, defaultOtelK8sConfig, cfg)
+	assert.Contains(t, cfg, "container_insights")
+	assert.NotContains(t, cfg, "host_metrics")
+}
+
+func TestDefaultJSONConfigFor_OtelECS(t *testing.T) {
+	cfg, ok := DefaultJSONConfigFor("otel", false, true)
+	require.True(t, ok)
+	assert.JSONEq(t, defaultOtelECSConfig, cfg)
+	assert.NotContains(t, cfg, "host_metrics")
+	assert.NotContains(t, cfg, "container_insights")
+}
+
+func TestDefaultJSONConfigFor_KubernetesTakesPrecedenceOverECS(t *testing.T) {
+	cfg, ok := DefaultJSONConfigFor("otel", true, true)
+	require.True(t, ok)
+	assert.JSONEq(t, defaultOtelK8sConfig, cfg)
+}
+
+func TestDefaultJSONConfigFor_VMFallsBackToBase(t *testing.T) {
+	cfg, ok := DefaultJSONConfigFor("otel", false, false)
+	require.True(t, ok)
+	assert.JSONEq(t, defaultOtelConfig, cfg)
+}
+
+func TestDefaultJSONConfigFor_UnknownWithPlatform(t *testing.T) {
+	_, ok := DefaultJSONConfigFor("unknown", true, false)
 	assert.False(t, ok)
 }

translator/config/defaults/otel.json

@@ -6,6 +6,7 @@
   },
   "opentelemetry": {
     "collect": {
+      "host_metrics": {},
       "otlp": {
         "span_metrics_enabled": true
       }

translator/config/defaults/otel_ecs.json

@@ -0,0 +1,14 @@
+{
+  "agent": {
+    "credentials": {
+      "role_arn": "${CWAGENT_ROLE_ARN}"
+    }
+  },
+  "opentelemetry": {
+    "collect": {
+      "otlp": {
+        "span_metrics_enabled": true
+      }
+    }
+  }
+}

translator/config/defaults/otel_k8s.json

@@ -0,0 +1,15 @@
+{
+  "agent": {
+    "credentials": {
+      "role_arn": "${CWAGENT_ROLE_ARN}"
+    }
+  },
+  "opentelemetry": {
+    "collect": {
+      "container_insights": {},
+      "otlp": {
+        "span_metrics_enabled": true
+      }
+    }
+  }
+}

translator/config/defaults/otel_windows.json

@@ -6,6 +6,7 @@
   },
   "opentelemetry": {
     "collect": {
+      "host_metrics": {},
       "otlp": {},
       "windows_events": {
         "collect_list": [

translator/jsonconfig/mergeJsonConfig.go

@@ -11,6 +11,7 @@ import (
 	"github.com/aws/amazon-cloudwatch-agent/internal/constants"
 	"github.com/aws/amazon-cloudwatch-agent/translator"
 	"github.com/aws/amazon-cloudwatch-agent/translator/config"
+	"github.com/aws/amazon-cloudwatch-agent/translator/context"
 	"github.com/aws/amazon-cloudwatch-agent/translator/jsonconfig/mergeJsonUtil"
 	_ "github.com/aws/amazon-cloudwatch-agent/translator/registerrules"
 	"github.com/aws/amazon-cloudwatch-agent/translator/util"
@@ -26,7 +27,7 @@ func MergeJsonConfigMaps(jsonConfigMapMap map[string]map[string]interface{}, def
 				log.Println("No json config files found, use the default ecs config")
 				return util.GetJsonMapFromJsonBytes([]byte(config.DefaultECSJsonConfig()))
 			}
-		} else if cfg, ok := config.DefaultJSONConfigFor(useDefault); ok {
+		} else if cfg, ok := config.DefaultJSONConfigFor(useDefault, context.CurrentContext().KubernetesMode() != "", util.DetectECS()); ok {
 			log.Printf("No json config files found, use the default %s config", useDefault)
 			return util.GetJsonMapFromJsonBytes([]byte(cfg))
 		}