Add namespace and log group name setting (#8)

metrics.go

@@ -171,6 +171,14 @@ func (l *Logger) Dimension(key, value string) *Logger {
 	return l
 }
 
+// Namespace sets the namespace for the Logger.
+func (l *Logger) Namespace(namespace string) *Logger {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.metrics.Namespace = namespace
+	return l
+}
+
 // Flush outputs the collected metrics to stdout so they can be discovered by CloudWatch.
 //
 // Typical usage in a lambda handler would be to populate metrics throughout and then

metrics_test.go

@@ -76,6 +76,22 @@ func TestMetricsLog(t *testing.T) {
 			},
 			want: "env.json",
 		},
+		{
+			name: "namespace",
+			logFn: func(logger *metrics.Logger) {
+				logger.Namespace("MyNameSpace").Add("Foo", 27, unit.Percent, metrics.StandardResolution)
+			},
+			want: "namespace.json",
+		},
+		{
+			name: "log group name",
+			logFn: func(logger *metrics.Logger) {
+				logger.Namespace("MyNameSpace").Add("Foo", 27, unit.Percent, metrics.StandardResolution)
+				fn := metrics.LogGroupName("MyLogGroup")
+				fn(logger)
+			},
+			want: "log-group-name.json",
+		},
 	}
 
 	for _, tt := range tests {

testdata/log-group-name.json

@@ -0,0 +1,32 @@
+{
+  "_aws": {
+    "Timestamp": "<<PRESENCE>>",
+    "LogGroupName": "MyLogGroup",
+    "CloudWatchMetrics": [
+      {
+        "Namespace": "MyNameSpace",
+        "Dimensions": [
+          [
+            "ServiceName",
+            "ServiceType"
+          ]
+        ],
+        "Metrics": [
+          {
+            "Name": "Foo",
+            "Unit": "Percent",
+            "StorageResolution": 60
+          }
+        ]
+      }
+    ]
+  },
+  "executionEnvironment": "",
+  "functionName": "",
+  "functionVersion": "",
+  "logStreamId": "",
+  "memorySize": "",
+  "ServiceName": "",
+  "ServiceType": "AWS::Lambda::Function",
+  "Foo": 27
+}

testdata/namespace.json

@@ -0,0 +1,31 @@
+{
+  "_aws": {
+    "Timestamp": "<<PRESENCE>>",
+    "CloudWatchMetrics": [
+      {
+        "Namespace": "MyNameSpace",
+        "Dimensions": [
+          [
+            "ServiceName",
+            "ServiceType"
+          ]
+        ],
+        "Metrics": [
+          {
+            "Name": "Foo",
+            "Unit": "Percent",
+            "StorageResolution": 60
+          }
+        ]
+      }
+    ]
+  },
+  "executionEnvironment": "",
+  "functionName": "",
+  "functionVersion": "",
+  "logStreamId": "",
+  "memorySize": "",
+  "ServiceName": "",
+  "ServiceType": "AWS::Lambda::Function",
+  "Foo": 27
+}