feat: Add append_dimensions tests for collectd, ethtool, and cpu plugins (#647)

* feat: Add append_dimensions tests for collectd, ethtool, and cpu plugins

* Address CR feedback: use shared helpers, extract summary table

- Refactor CollectdFleetAggregationTestRunner to use DimensionSpec helpers
  instead of manual dimension.Instruction construction
- Add EC2-specific comment for hardcoded 'ena' driver name
- Change fmt.Printf to log.Printf in isAllValuesGreaterThanOrEqualToZero
  to preserve timestamps in output
- Move printTestSummaryTable and testDescriptions to test_summary_helpers.go

Author: TravisStark

test/metric_dimension/agent_configs/collectd_append_dimensions.json

@@ -0,0 +1,25 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "CollectdAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["InstanceId", "InstanceType", "host", "type"]
+    ],
+    "metrics_collected": {
+      "collectd": {
+        "metrics_aggregation_interval": 30,
+        "collectd_security_level": "none",
+        "append_dimensions": {
+          "InstanceId": "${aws:InstanceId}",
+          "InstanceType": "${aws:InstanceType}"
+        }
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/collectd_fleet_aggregation.json

@@ -0,0 +1,27 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "CollectdFleetAggregationTest",
+    "aggregation_dimensions": [
+      ["Component", "type", "InstanceId"],
+      ["Component", "type"],
+      ["Component", "type", "host"]
+    ],
+    "metrics_collected": {
+      "collectd": {
+        "metrics_aggregation_interval": 30,
+        "collectd_security_level": "none",
+        "append_dimensions": {
+          "InstanceId": "${aws:InstanceId}",
+          "Component": "WebServer"
+        }
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/collectd_global_append_dimensions.json

@@ -0,0 +1,25 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "CollectdGlobalAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["InstanceId", "InstanceType", "type"]
+    ],
+    "append_dimensions": {
+      "InstanceId": "${aws:InstanceId}",
+      "InstanceType": "${aws:InstanceType}"
+    },
+    "metrics_collected": {
+      "collectd": {
+        "metrics_aggregation_interval": 30,
+        "collectd_security_level": "none"
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/collectd_no_append_dimensions.json

@@ -0,0 +1,21 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "CollectdNoAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["host", "type"]
+    ],
+    "metrics_collected": {
+      "collectd": {
+        "metrics_aggregation_interval": 30,
+        "collectd_security_level": "none"
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/cpu_global_append_dimensions.json

@@ -0,0 +1,24 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "CpuGlobalAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["InstanceId", "InstanceType", "cpu"]
+    ],
+    "append_dimensions": {
+      "InstanceId": "${aws:InstanceId}",
+      "InstanceType": "${aws:InstanceType}"
+    },
+    "metrics_collected": {
+      "cpu": {
+        "measurement": ["time_active"]
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/ethtool_append_dimensions.json

@@ -0,0 +1,25 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "EthtoolAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["InstanceId", "InstanceType", "interface", "driver"]
+    ],
+    "append_dimensions": {
+      "InstanceId": "${aws:InstanceId}",
+      "InstanceType": "${aws:InstanceType}"
+    },
+    "metrics_collected": {
+      "ethtool": {
+        "interface_include": ["eth0", "ens5"],
+        "metrics_include": ["queue_0_tx_cnt", "queue_0_rx_cnt"]
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/agent_configs/ethtool_plugin_append_dimensions.json

@@ -0,0 +1,25 @@
+{
+  "agent": {
+    "metrics_collection_interval": 10,
+    "run_as_user": "root",
+    "debug": true,
+    "logfile": ""
+  },
+  "metrics": {
+    "namespace": "EthtoolPluginAppendDimensionsTest",
+    "aggregation_dimensions": [
+      ["InstanceId", "InstanceType", "host", "interface", "driver"]
+    ],
+    "metrics_collected": {
+      "ethtool": {
+        "interface_include": ["eth0", "ens5"],
+        "metrics_include": ["queue_0_tx_cnt", "queue_0_rx_cnt"],
+        "append_dimensions": {
+          "InstanceId": "${aws:InstanceId}",
+          "InstanceType": "${aws:InstanceType}"
+        }
+      }
+    },
+    "force_flush_interval": 5
+  }
+}

test/metric_dimension/collectd_append_dimensions_test.go

@@ -0,0 +1,79 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !windows
+
+package metric_dimension
+
+import (
+	"log"
+	"time"
+
+	"github.com/aws/amazon-cloudwatch-agent-test/test/metric"
+	"github.com/aws/amazon-cloudwatch-agent-test/test/status"
+	"github.com/aws/amazon-cloudwatch-agent-test/test/test_runner"
+	"github.com/aws/amazon-cloudwatch-agent-test/util/common"
+)
+
+// CollectdAppendDimensionsTestRunner tests plugin-level append_dimensions for collectd.
+//
+// Per the CloudWatch Agent documentation, plugin-level append_dimensions ADDS dimensions
+// to the metrics without dropping existing dimensions like 'host'. This is different from
+// global append_dimensions which drops the 'host' dimension.
+//
+// This test validates that with plugin-level append_dimensions:
+// 1. The configured dimensions (InstanceId, InstanceType) ARE added
+// 2. The original 'host' dimension from collectd protocol is KEPT (not dropped)
+type CollectdAppendDimensionsTestRunner struct {
+	test_runner.BaseTestRunner
+}
+
+var _ test_runner.ITestRunner = (*CollectdAppendDimensionsTestRunner)(nil)
+
+func (t *CollectdAppendDimensionsTestRunner) Validate() status.TestGroupResult {
+	metricsToFetch := t.GetMeasuredMetrics()
+	testResults := make([]status.TestResult, len(metricsToFetch))
+	for i, metricName := range metricsToFetch {
+		testResults[i] = t.validateCollectdAppendDimensionMetric(metricName)
+	}
+
+	return status.TestGroupResult{
+		Name:        t.GetTestName(),
+		TestResults: testResults,
+	}
+}
+
+func (t *CollectdAppendDimensionsTestRunner) GetTestName() string {
+	return "CollectdAppendDimensions"
+}
+
+func (t *CollectdAppendDimensionsTestRunner) GetAgentConfigFileName() string {
+	return "collectd_append_dimensions.json"
+}
+
+func (t *CollectdAppendDimensionsTestRunner) SetupAfterAgentRun() error {
+	return common.SendCollectDMetrics(2, time.Second, t.GetAgentRunDuration())
+}
+
+func (t *CollectdAppendDimensionsTestRunner) GetMeasuredMetrics() []string {
+	return []string{"collectd_gauge_1_value"}
+}
+
+func (t *CollectdAppendDimensionsTestRunner) GetAgentRunDuration() time.Duration {
+	return 2 * time.Minute
+}
+
+func (t *CollectdAppendDimensionsTestRunner) validateCollectdAppendDimensionMetric(metricName string) status.TestResult {
+	metricType := metric.GetCollectDMetricType(metricName)
+	ns := "CollectdAppendDimensionsTest"
+
+	// With plugin-level append_dimensions, BOTH the configured dimensions AND the original
+	// host dimension should be present.
+	specs := append(EC2Dims(), HostDim(), ExactDim("type", metricType))
+
+	result := ValidateDimensionsPresent(&t.BaseTestRunner, ns, metricName, specs)
+	if result.Status == status.SUCCESSFUL {
+		log.Printf("Verified: plugin-level append_dimensions adds InstanceId/InstanceType while keeping host dimension")
+	}
+	return result
+}

test/metric_dimension/collectd_fleet_aggregation_test.go

@@ -0,0 +1,103 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !windows
+
+package metric_dimension
+
+import (
+	"log"
+	"time"
+
+	"github.com/aws/amazon-cloudwatch-agent-test/test/metric"
+	"github.com/aws/amazon-cloudwatch-agent-test/test/status"
+	"github.com/aws/amazon-cloudwatch-agent-test/test/test_runner"
+	"github.com/aws/amazon-cloudwatch-agent-test/util/common"
+)
+
+// CollectdFleetAggregationTestRunner tests fleet aggregation with plugin-level append_dimensions.
+//
+// This test uses plugin-level append_dimensions (under metrics_collected.collectd.append_dimensions)
+// which ADDS dimensions without dropping the 'host' dimension. The aggregation_dimensions config
+// controls which dimension combinations are published to CloudWatch.
+//
+// The test validates:
+// 1. Aggregated metrics with [Component, type] dimensions exist (fleet-wide aggregation)
+// 2. Aggregated metrics with [Component, type, InstanceId] dimensions exist (per-instance)
+// 3. The host dimension is KEPT (plugin-level behavior) - verified via aggregation_dimensions
+type CollectdFleetAggregationTestRunner struct {
+	test_runner.BaseTestRunner
+}
+
+var _ test_runner.ITestRunner = (*CollectdFleetAggregationTestRunner)(nil)
+
+func (t *CollectdFleetAggregationTestRunner) Validate() status.TestGroupResult {
+	metricsToFetch := t.GetMeasuredMetrics()
+	testResults := make([]status.TestResult, len(metricsToFetch))
+	for i, metricName := range metricsToFetch {
+		testResults[i] = t.validateCollectdFleetAggregationMetric(metricName)
+	}
+
+	return status.TestGroupResult{
+		Name:        t.GetTestName(),
+		TestResults: testResults,
+	}
+}
+
+func (t *CollectdFleetAggregationTestRunner) GetTestName() string {
+	return "CollectdFleetAggregation"
+}
+
+func (t *CollectdFleetAggregationTestRunner) GetAgentConfigFileName() string {
+	return "collectd_fleet_aggregation.json"
+}
+
+func (t *CollectdFleetAggregationTestRunner) SetupAfterAgentRun() error {
+	return common.SendCollectDMetrics(2, time.Second, t.GetAgentRunDuration())
+}
+
+func (t *CollectdFleetAggregationTestRunner) GetMeasuredMetrics() []string {
+	return []string{"collectd_gauge_1_value"}
+}
+
+func (t *CollectdFleetAggregationTestRunner) GetAgentRunDuration() time.Duration {
+	return 2 * time.Minute
+}
+
+func (t *CollectdFleetAggregationTestRunner) validateCollectdFleetAggregationMetric(metricName string) status.TestResult {
+	metricType := metric.GetCollectDMetricType(metricName)
+	ns := "CollectdFleetAggregationTest"
+
+	// Test 1: Fleet-aggregated dimensions (Component + type from aggregation_dimensions)
+	fleetSpecs := []DimensionSpec{
+		ExactDim("Component", "WebServer"),
+		ExactDim("type", metricType),
+	}
+	result := ValidateDimensionsPresent(&t.BaseTestRunner, ns, metricName, fleetSpecs)
+	if result.Status != status.SUCCESSFUL {
+		return result
+	}
+
+	// Test 2: Per-instance aggregated dimensions (Component + type + InstanceId)
+	instanceSpecs := []DimensionSpec{
+		ExactDim("Component", "WebServer"),
+		ExactDim("type", metricType),
+		{Key: "InstanceId"},
+	}
+	result = ValidateDimensionsPresent(&t.BaseTestRunner, ns, metricName, instanceSpecs)
+	if result.Status != status.SUCCESSFUL {
+		return result
+	}
+
+	// Test 3: Host dimension is KEPT (plugin-level append_dimensions does NOT drop host)
+	hostSpecs := []DimensionSpec{
+		ExactDim("Component", "WebServer"),
+		ExactDim("type", metricType),
+		HostDim(),
+	}
+	result = ValidateDimensionsPresent(&t.BaseTestRunner, ns, metricName, hostSpecs)
+	if result.Status == status.SUCCESSFUL {
+		log.Printf("Verified: plugin-level append_dimensions keeps host dimension and aggregation_dimensions controls published combinations")
+	}
+	return result
+}