feat(logger): pretty printing logs in local and non-prod environment

packages/logger/src/Logger.ts

@@ -6,6 +6,7 @@ import { LogItem } from './log';
 import cloneDeep from 'lodash.clonedeep';
 import merge from 'lodash.merge';
 import { ConfigServiceInterface, EnvironmentVariablesService } from './config';
+import { LogJsonIndent } from './types';
 import type {
   ClassThatLogs,
   Environment,
@@ -569,7 +570,10 @@ class Logger extends Utility implements ClassThatLogs {
 
     const consoleMethod = logLevel.toLowerCase() as keyof ClassThatLogs;
 
-    this.console[consoleMethod](JSON.stringify(log.getAttributes(), this.removeCircularDependencies()));
+    const isDevMode = this.getEnvVarsService().getDevMode();
+    const INDENTATION: LogJsonIndent = isDevMode ? LogJsonIndent.PRETTY : LogJsonIndent.COMPACT;
+
+    this.console[consoleMethod](JSON.stringify(log.getAttributes(), this.removeCircularDependencies(), INDENTATION));
   }
 
   /**

packages/logger/src/config/ConfigServiceInterface.ts

@@ -22,6 +22,13 @@ interface ConfigServiceInterface {
    */
   getCurrentEnvironment(): string
 
+  /**
+   * It returns the value of the POWERTOOLS_DEV environment variable.
+   *
+   * @returns {boolean}
+   */
+  getDevMode(): boolean
+
   /**
    * It returns the value of the POWERTOOLS_LOGGER_LOG_EVENT environment variable.
    *

packages/logger/src/config/EnvironmentVariablesService.ts

@@ -20,6 +20,7 @@ class EnvironmentVariablesService extends CommonEnvironmentVariablesService impl
   // Reserved environment variables
   private awsRegionVariable = 'AWS_REGION';
   private currentEnvironmentVariable = 'ENVIRONMENT';
+  private devModeVariable = 'POWERTOOLS_DEV';
   private functionNameVariable = 'AWS_LAMBDA_FUNCTION_NAME';
   private functionVersionVariable = 'AWS_LAMBDA_FUNCTION_VERSION';
   private logEventVariable = 'POWERTOOLS_LOGGER_LOG_EVENT';
@@ -45,6 +46,17 @@ class EnvironmentVariablesService extends CommonEnvironmentVariablesService impl
     return this.get(this.currentEnvironmentVariable);
   }
 
+  /**
+   * It returns the value of the POWERTOOLS_DEV environment variable.
+   *
+   * @returns {boolean}
+   */
+  public getDevMode(): boolean {
+    const value = this.get(this.devModeVariable);
+
+    return value.toLowerCase() === 'true' || value === '1';
+  }
+
   /**
    * It returns the value of the AWS_LAMBDA_FUNCTION_MEMORY_SIZE environment variable.
    *

packages/logger/src/types/Logger.ts

@@ -74,3 +74,8 @@ export {
   ConstructorOptions,
   HandlerOptions
 };
+
+export const enum LogJsonIndent {
+  PRETTY = 4,
+  COMPACT = 0,
+}

packages/logger/tests/unit/Logger.test.ts

@@ -11,7 +11,7 @@ import * as dummyEvent from '../../../../tests/resources/events/custom/hello-wor
 import { createLogger, Logger } from '../../src';
 import { EnvironmentVariablesService } from '../../src/config';
 import { PowertoolLogFormatter } from '../../src/formatter';
-import { ClassThatLogs } from '../../src/types';
+import { ClassThatLogs, LogJsonIndent } from '../../src/types';
 import { Context, Handler } from 'aws-lambda';
 import { Console } from 'console';
 
@@ -1411,4 +1411,49 @@ describe('Class: Logger', () => {
     });
   });
 
+  describe('Feature: Pretty indentation for a local or non-production environment', () => {
+
+    test('when the `POWERTOOLS_DEV` env var is SET it makes log output has multiple lines', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'true';
+      const INDENTATION = LogJsonIndent.PRETTY;
+      const logger = new Logger();
+      const consoleSpy = jest.spyOn(logger['console'], 'info').mockImplementation();
+
+      // Act
+      logger.info('Message with pretty identation');
+
+      // Assess
+      expect(consoleSpy).toBeCalledTimes(1);
+      expect(consoleSpy).toHaveBeenNthCalledWith(1, JSON.stringify({
+        level: 'INFO',
+        message: 'Message with pretty identation',
+        service: 'hello-world',
+        timestamp: '2016-06-20T12:08:10.000Z',
+        xray_trace_id: '1-5759e988-bd862e3fe1be46a994272793',
+      }, null, INDENTATION));
+    });
+
+    test('when the `POWERTOOLS_DEV` env var is NOT SET it makes log output as one-liner', () => {
+
+      // Prepare
+      const logger = new Logger();
+      const consoleSpy = jest.spyOn(logger['console'], 'info').mockImplementation();
+
+      // Act
+      logger.info('Message without pretty identation');
+
+      // Assess
+      expect(consoleSpy).toBeCalledTimes(1);
+      expect(consoleSpy).toHaveBeenNthCalledWith(1, JSON.stringify({
+        level: 'INFO',
+        message: 'Message without pretty identation',
+        service: 'hello-world',
+        timestamp: '2016-06-20T12:08:10.000Z',
+        xray_trace_id: '1-5759e988-bd862e3fe1be46a994272793',
+      }));
+    });
+  });
+
 });

packages/logger/tests/unit/config/EnvironmentVariablesService.test.ts

@@ -220,4 +220,112 @@ describe('Class: EnvironmentVariablesService', () => {
 
   });
 
+  describe('Method: getDevMode', () => {
+
+    test('It returns true if the environment variable POWERTOOLS_DEV is "true"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'true';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(true);
+    });
+
+    test('It returns true if the environment variable POWERTOOLS_DEV is "TRUE"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'TRUE';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(true);
+    });
+
+    test('It returns true if the environment variable POWERTOOLS_DEV is "1"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = '1';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(true);
+    });
+
+    test('It returns false if the environment variable POWERTOOLS_DEV is "false"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'false';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(false);
+    });
+
+    test('It returns false if the environment variable POWERTOOLS_DEV is "FALSE"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'FALSE';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(false);
+    });
+
+    test('It returns false if the environment variable POWERTOOLS_DEV is "0"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = '0';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(false);
+    });
+
+    test('It returns false if the environment variable POWERTOOLS_DEV is NOT set', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'somethingsilly';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(false);
+    });
+
+    test('It returns false if the environment variable POWERTOOLS_DEV is "somethingsilly"', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_DEV = 'somethingsilly';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getDevMode();
+
+      // Assess
+      expect(value).toEqual(false);
+    });
+
+  });
+
 });

packages/logger/tests/unit/helpers.test.ts

@@ -307,7 +307,10 @@ describe('Helper: createLogger function', () => {
         getServiceName(): string {
           return 'my-backend-service';
         },
-
+        getDevMode(): boolean {
+          return false;
+        },
+
       };
       // Prepare
       const loggerOptions:ConstructorOptions = {

packages/logger/tests/unit/middleware/middy.test.ts

@@ -336,6 +336,9 @@ describe('Middy middleware', () => {
         getServiceName(): string {
           return 'my-backend-service';
         },
+        getDevMode(): boolean {
+          return false;
+        },
 
       };