feat: Raise error on empty metrics and validations

Author: Pankaj Agrawal

pom.xml

@@ -68,7 +68,7 @@
         <maven-source-plugin.version>3.2.1</maven-source-plugin.version>
         <maven-gpg-plugin.version>1.6</maven-gpg-plugin.version>
         <junit-jupiter.version>5.6.2</junit-jupiter.version>
-        <aws-embedded-metrics.version>1.0.0</aws-embedded-metrics.version>
+        <aws-embedded-metrics.version>0.1.0-beta</aws-embedded-metrics.version>
     </properties>
 
     <distributionManagement>

powertools-metrics/src/main/java/software/amazon/cloudwatchlogs/emf/model/MetricsLoggerHelper.java

@@ -0,0 +1,28 @@
+package software.amazon.cloudwatchlogs.emf.model;
+
+import java.lang.reflect.Field;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public final class MetricsLoggerHelper {
+    private MetricsLoggerHelper() {
+    }
+
+    public static boolean hasNoMetrics() {
+        return metricsContext().getRootNode().getAws().isEmpty();
+    }
+
+    public static long dimensionsCount() {
+        return metricsContext().getDimensions().size();
+    }
+
+    private static MetricsContext metricsContext() {
+        try {
+            Field f = metricsLogger().getClass().getDeclaredField("context");
+            f.setAccessible(true);
+            return (MetricsContext) f.get(metricsLogger());
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/PowertoolsMetrics.java

@@ -26,6 +26,10 @@
  * </br>This will create a metric with the key {@code "ColdStart"} and the unit type {@code COUNT}.
  * </p>
  *
+ * <p>To raise exception if no metrics are emitted, use {@code @PowertoolsMetrics(raiseOnEmptyMetrics = true)}.
+ * </br>This will create a create a exception of type {@link ValidationException}. By default its value is set to false.
+ * </p>
+ *
  * <p>By default the service name associated with metrics created will be
  * "service_undefined". This can be overridden with the environment variable {@code POWERTOOLS_SERVICE_NAME}
  * or the annotation variable {@code @PowertoolsMetrics(service = "Service Name")}.
@@ -42,4 +46,5 @@
     String namespace() default "";
     String service() default "";
     boolean captureColdStart() default false;
+    boolean raiseOnEmptyMetrics() default false;
 }

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/PowertoolsMetricsLogger.java

@@ -1,10 +1,10 @@
 package software.amazon.lambda.powertools.metrics;
 
+import java.util.function.Consumer;
+
 import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
 import software.amazon.cloudwatchlogs.emf.model.Unit;
 
-import java.util.function.Consumer;
-
 /**
  * A class used to retrieve the instance of the {@code MetricsLogger} used by
  * {@code PowertoolsMetrics}.
@@ -14,6 +14,9 @@
 public final class PowertoolsMetricsLogger {
     private static final MetricsLogger metricsLogger = new MetricsLogger();
 
+    private PowertoolsMetricsLogger() {
+    }
+
     /**
      * The instance of the {@code MetricsLogger} used by {@code PowertoolsMetrics}.
      *

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/ValidationException.java

@@ -0,0 +1,8 @@
+package software.amazon.lambda.powertools.metrics;
+
+public class ValidationException extends RuntimeException {
+
+    public ValidationException(String message) {
+        super(message);
+    }
+}

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/internal/LambdaMetricsAspect.java

@@ -1,5 +1,6 @@
 package software.amazon.lambda.powertools.metrics.internal;
 
+import java.lang.reflect.Field;
 import java.util.Optional;
 
 import com.amazonaws.services.lambda.runtime.Context;
@@ -9,9 +10,13 @@
 import org.aspectj.lang.annotation.Pointcut;
 import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
 import software.amazon.cloudwatchlogs.emf.model.DimensionSet;
+import software.amazon.cloudwatchlogs.emf.model.MetricsContext;
 import software.amazon.cloudwatchlogs.emf.model.Unit;
 import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+import software.amazon.lambda.powertools.metrics.ValidationException;
 
+import static software.amazon.cloudwatchlogs.emf.model.MetricsLoggerHelper.dimensionsCount;
+import static software.amazon.cloudwatchlogs.emf.model.MetricsLoggerHelper.hasNoMetrics;
 import static software.amazon.lambda.powertools.core.internal.LambdaHandlerProcessor.coldStartDone;
 import static software.amazon.lambda.powertools.core.internal.LambdaHandlerProcessor.extractContext;
 import static software.amazon.lambda.powertools.core.internal.LambdaHandlerProcessor.isColdStart;
@@ -47,11 +52,19 @@ public Object around(ProceedingJoinPoint pjp,
 
             coldStartSingleMetricIfApplicable(pjp, powertoolsMetrics);
 
-            Object proceed = pjp.proceed(proceedArgs);
+            try {
+                Object proceed = pjp.proceed(proceedArgs);
 
-            coldStartDone();
-            logger.flush();
-            return proceed;
+                coldStartDone();
+
+                validateBeforeFlushingMetrics(powertoolsMetrics);
+
+                logger.flush();
+                return proceed;
+
+            } finally {
+                refreshMetricsContext();
+            }
         }
 
         return pjp.proceed(proceedArgs);
@@ -74,11 +87,32 @@ && isColdStart()) {
         }
     }
 
+    private void validateBeforeFlushingMetrics(PowertoolsMetrics powertoolsMetrics) {
+        if (powertoolsMetrics.raiseOnEmptyMetrics() && hasNoMetrics()) {
+            throw new ValidationException("No metrics captured, at least one metrics must be emitted");
+        }
+
+        if (dimensionsCount() == 0 || dimensionsCount() > 10) {
+            throw new ValidationException(String.format("Number of Dimensions must be in range of 1-10." +
+                    " Actual size: %d.", dimensionsCount()));
+        }
+    }
+
     private String namespace(PowertoolsMetrics powertoolsMetrics) {
         return !"".equals(powertoolsMetrics.namespace()) ? powertoolsMetrics.namespace() : NAMESPACE;
     }
 
     private String service(PowertoolsMetrics powertoolsMetrics) {
         return !"".equals(powertoolsMetrics.service()) ? powertoolsMetrics.service() : serviceName();
     }
+
+    private static void refreshMetricsContext() {
+        try {
+            Field f = metricsLogger().getClass().getDeclaredField("context");
+            f.setAccessible(true);
+            f.set(metricsLogger(), new MetricsContext());
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
 }

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsExceptionWhenNoMetricsHandler.java

@@ -0,0 +1,20 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsExceptionWhenNoMetricsHandler implements RequestHandler<Object, Object> {
+
+    @Override
+    @PowertoolsMetrics(namespace = "ExampleApplication", service = "booking", raiseOnEmptyMetrics = true)
+    public Object handleRequest(Object input, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+        metricsLogger.putMetadata("MetaData", "MetaDataValue");
+
+        return null;
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsNoDimensionsHandler.java

@@ -0,0 +1,25 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import java.util.function.IntConsumer;
+import java.util.stream.IntStream;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.cloudwatchlogs.emf.model.DimensionSet;
+import software.amazon.cloudwatchlogs.emf.model.Unit;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsNoDimensionsHandler implements RequestHandler<Object, Object> {
+
+    @Override
+    @PowertoolsMetrics(namespace = "ExampleApplication", service = "booking", captureColdStart = true)
+    public Object handleRequest(Object input, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+        metricsLogger.setDimensions();
+
+        return null;
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsNoExceptionWhenNoMetricsHandler.java

@@ -0,0 +1,20 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsNoExceptionWhenNoMetricsHandler implements RequestHandler<Object, Object> {
+
+    @Override
+    @PowertoolsMetrics(namespace = "ExampleApplication", service = "booking")
+    public Object handleRequest(Object input, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+        metricsLogger.putMetadata("MetaData", "MetaDataValue");
+
+        return null;
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsTooManyDimensionsHandler.java

@@ -0,0 +1,28 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.cloudwatchlogs.emf.model.DimensionSet;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsTooManyDimensionsHandler implements RequestHandler<Object, Object> {
+
+    @Override
+    @PowertoolsMetrics
+    public Object handleRequest(Object input, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+
+        metricsLogger.setDimensions(IntStream.range(1, 15)
+                .mapToObj(value -> DimensionSet.of("Dimension" + value, "DimensionValue" + value))
+                .toArray(DimensionSet[]::new));
+
+        return null;
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/internal/LambdaMetricsAspectTest.java

@@ -19,13 +19,19 @@
 import org.mockito.MockedStatic;
 import software.amazon.cloudwatchlogs.emf.config.SystemWrapper;
 import software.amazon.lambda.powertools.core.internal.LambdaHandlerProcessor;
+import software.amazon.lambda.powertools.metrics.ValidationException;
 import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsColdStartEnabledHandler;
 import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsEnabledHandler;
 import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsEnabledStreamHandler;
+import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsExceptionWhenNoMetricsHandler;
+import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsNoDimensionsHandler;
+import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsNoExceptionWhenNoMetricsHandler;
+import software.amazon.lambda.powertools.metrics.handlers.PowertoolsMetricsTooManyDimensionsHandler;
 
 import static java.util.Collections.emptyMap;
 import static org.apache.commons.lang3.reflect.FieldUtils.writeStaticField;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.Mockito.mockStatic;
 import static org.mockito.Mockito.when;
 import static org.mockito.MockitoAnnotations.openMocks;
@@ -171,6 +177,61 @@ public void metricsWithStreamHandler() throws IOException {
         }
     }
 
+    @Test
+    public void exceptionWhenNoMetricsEmitted() {
+        requestHandler = new PowertoolsMetricsExceptionWhenNoMetricsHandler();
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+
+            assertThatExceptionOfType(ValidationException.class)
+                    .isThrownBy(() -> requestHandler.handleRequest("input", context))
+                    .withMessage("No metrics captured, at least one metrics must be emitted");
+        }
+    }
+
+    @Test
+    public void noExceptionWhenNoMetricsEmitted() {
+        requestHandler = new PowertoolsMetricsNoExceptionWhenNoMetricsHandler();
+
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+            requestHandler.handleRequest("input", context);
+
+            assertThat(out.toString())
+                    .satisfies(s -> {
+                        Map<String, Object> logAsJson = readAsJson(s);
+
+                        assertThat(logAsJson)
+                                .containsEntry("service", "booking")
+                                .doesNotContainKey("_aws");
+                    });
+        }
+    }
+
+    @Test
+    public void exceptionWhenNoDimensionsSet() {
+        requestHandler = new PowertoolsMetricsNoDimensionsHandler();
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+
+            assertThatExceptionOfType(ValidationException.class)
+                    .isThrownBy(() -> requestHandler.handleRequest("input", context))
+                    .withMessage("Number of Dimensions must be in range of 1-10. Actual size: 0.");
+        }
+    }
+
+    @Test
+    public void exceptionWhenTooManyDimensionsSet() {
+        requestHandler = new PowertoolsMetricsTooManyDimensionsHandler();
+
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+
+            assertThatExceptionOfType(ValidationException.class)
+                    .isThrownBy(() -> requestHandler.handleRequest("input", context))
+                    .withMessage("Number of Dimensions must be in range of 1-10. Actual size: 14.");
+        }
+    }
 
     private void setupContext() {
         when(context.getFunctionName()).thenReturn("testFunction");