chore(logger): set default UTC timezone

packages/logger/src/Logger.ts

@@ -930,7 +930,9 @@ class Logger extends Utility implements LoggerInterface {
    * @returns {void}
    */
   private setLogFormatter(logFormatter?: LogFormatterInterface): void {
-    this.logFormatter = logFormatter ?? new PowertoolsLogFormatter();
+    this.logFormatter =
+      logFormatter ??
+      new PowertoolsLogFormatter({ envVarsService: this.getEnvVarsService() });
   }
 
   /**
@@ -965,8 +967,8 @@ class Logger extends Utility implements LoggerInterface {
       environment,
     } = options;
 
+    // order is important, EnvVarsService() is used by other methods
     this.setEnvVarsService();
-    // order is important, it uses EnvVarsService()
     this.setConsole();
     this.setCustomConfigService(customConfigService);
     this.setInitialLogLevel(logLevel);
@@ -975,7 +977,6 @@ class Logger extends Utility implements LoggerInterface {
     this.setInitialSampleRate(sampleRateValue);
     this.setLogEvent();
     this.setLogIndentation();
-
     this.addPersistentLogAttributes(persistentLogAttributes);
 
     return this;

packages/logger/src/config/EnvironmentVariablesService.ts

@@ -29,6 +29,7 @@ class EnvironmentVariablesService
   private logLevelVariable = 'LOG_LEVEL';
   private memoryLimitInMBVariable = 'AWS_LAMBDA_FUNCTION_MEMORY_SIZE';
   private sampleRateValueVariable = 'POWERTOOLS_LOGGER_SAMPLE_RATE';
+  private tzVariable = 'TZ';
 
   /**
    * It returns the value of the AWS_REGION environment variable.
@@ -108,6 +109,17 @@ class EnvironmentVariablesService
     return value && value.length > 0 ? Number(value) : undefined;
   }
 
+  /**
+   * It returns the value of the `TZ` environment variable or `UTC` if it is not set.
+   *
+   * @returns {string}
+   */
+  public getTimezone(): string {
+    const value = this.get(this.tzVariable);
+
+    return value.length > 0 ? value : 'UTC';
+  }
+
   /**
    * It returns true if the POWERTOOLS_DEV environment variable is set to truthy value.
    *

packages/logger/src/formatter/LogFormatter.ts

@@ -1,4 +1,9 @@
-import type { LogAttributes, LogFormatterInterface } from '../types/Log.js';
+import type { EnvironmentVariablesService } from '../config/EnvironmentVariablesService.js';
+import type {
+  LogAttributes,
+  LogFormatterInterface,
+  LogFormatterOptions,
+} from '../types/Log.js';
 import type { UnformattedAttributes } from '../types/Logger.js';
 import { LogItem } from './LogItem.js';
 
@@ -10,6 +15,16 @@ import { LogItem } from './LogItem.js';
  * @implements {LogFormatterInterface}
  */
 abstract class LogFormatter implements LogFormatterInterface {
+  /**
+   * EnvironmentVariablesService instance.
+   * If set, it allows to access environment variables.
+   */
+  protected envVarsService?: EnvironmentVariablesService;
+
+  public constructor(options?: LogFormatterOptions) {
+    this.envVarsService = options?.envVarsService;
+  }
+
   /**
    * It formats key-value pairs of log attributes.
    *

packages/logger/src/types/Log.ts

@@ -1,3 +1,4 @@
+import type { EnvironmentVariablesService } from '../config/EnvironmentVariablesService.js';
 import type { LogItem } from '../formatter/LogItem.js';
 import type { UnformattedAttributes } from './Logger.js';
 
@@ -125,6 +126,14 @@ interface LogItemInterface {
   setAttributes(attributes: LogAttributes): void;
 }
 
+type LogFormatterOptions = {
+  /**
+   * EnvironmentVariablesService instance.
+   * If set, it gives the LogFormatter access to environment variables.
+   */
+  envVarsService?: EnvironmentVariablesService;
+};
+
 /**
  * @interface
  */
@@ -175,5 +184,6 @@ export type {
   LogLevel,
   PowertoolsLog,
   LogItemInterface,
+  LogFormatterOptions,
   LogFormatterInterface,
 };

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

@@ -153,6 +153,31 @@ describe('Class: EnvironmentVariablesService', () => {
     });
   });
 
+  describe('Method: getTimezone', () => {
+    it('returns the value of the TZ environment variable when set', () => {
+      // Prepare
+      process.env.TZ = 'Europe/London';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getTimezone();
+
+      // Assess
+      expect(value).toEqual('Europe/London');
+    });
+
+    it('returns the default UTC value when no TZ is set', () => {
+      // Prepare
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getTimezone();
+
+      // Assess
+      expect(value).toEqual('UTC');
+    });
+  });
+
   describe('Method: isDevMode', () => {
     test('it returns true if the environment variable POWERTOOLS_DEV is "true"', () => {
       // Prepare

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

@@ -222,7 +222,7 @@ describe('Class: Logger', () => {
           envVarsService: expect.any(EnvironmentVariablesService),
           customConfigService: undefined,
           logLevel: 8,
-          logFormatter: {},
+          logFormatter: expect.any(PowertoolsLogFormatter),
         })
       );
     });
@@ -344,7 +344,7 @@ describe('Class: Logger', () => {
           envVarsService: expect.any(EnvironmentVariablesService),
           customConfigService: undefined,
           logLevel: 8,
-          logFormatter: {},
+          logFormatter: expect.any(PowertoolsLogFormatter),
         })
       );
     });
@@ -398,7 +398,7 @@ describe('Class: Logger', () => {
           envVarsService: expect.any(EnvironmentVariablesService),
           customConfigService: configService,
           logLevel: 12,
-          logFormatter: {},
+          logFormatter: expect.any(PowertoolsLogFormatter),
         })
       );
     });
@@ -440,7 +440,7 @@ describe('Class: Logger', () => {
           envVarsService: expect.any(EnvironmentVariablesService),
           customConfigService: undefined,
           logLevel: 8,
-          logFormatter: {},
+          logFormatter: expect.any(PowertoolsLogFormatter),
         })
       );
     });
@@ -468,7 +468,7 @@ describe('Class: Logger', () => {
           envVarsService: expect.any(EnvironmentVariablesService),
           customConfigService: undefined,
           logLevel: 8,
-          logFormatter: {},
+          logFormatter: expect.any(PowertoolsLogFormatter),
         })
       );
     });

packages/tracer/tests/helpers/tracesUtils.ts

@@ -314,8 +314,8 @@ export {
   getInvocationSubsegment,
   splitSegmentsByName,
   invokeAllTestCases,
-  ParsedDocument,
-  ParsedSegment,
-  ParsedTrace,
-  AssertAnnotationParams,
+  type ParsedDocument,
+  type ParsedSegment,
+  type ParsedTrace,
+  type AssertAnnotationParams,
 };