npm run test
npm run example:hello-world
npm run example:inject-context
npm run example:inject-context-decorator
npm run example:inject-context-middleware
npm run example:errors
npm run example:constructor-options
npm run example:custom-log-formatter
npm run example:child-logger
npm run example:additional-keys
npm run example:sample-rate
npm run example:persistent-attributes
npm run example:ephemeral-attributes
// Import the library
import { Logger } from '../src';
// When going public, it will be something like: import { Logger } from '@aws-lambda-powertools/logger';
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'WARN';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
// Instantiate the Logger with default configuration
const logger = new Logger();
// Log with different levels
logger.debug('This is a DEBUG log');
logger.info('This is an INFO log');
logger.warn('This is a WARN log');
logger.error('This is an ERROR log');Click to expand and see the logs outputs
{
level: 'WARN',
message: 'This is a WARN log',
service: 'hello-world',
timestamp: '2021-03-13T18:02:49.280Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
{
level: 'ERROR',
message: 'This is an ERROR log',
service: 'hello-world',
timestamp: '2021-03-13T18:02:49.282Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
With the middy middleware injectLambdaContext:
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'INFO';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
import { injectLambdaContext } from '../src/middleware/middy';
import middy from '@middy/core';
const logger = new Logger();
const lambdaHandler: Handler = async () => {
logger.info('This is an INFO log');
return {
foo: 'bar'
};
};
const handlerWithMiddleware = middy(lambdaHandler)
.use(injectLambdaContext(logger));Click to expand and see the logs outputs
{
aws_request_id: 'c6af9ac6-7b61-11e6-9a41-93e812345678',
cold_start: true,
lambda_function_arn: 'arn:aws:lambda:eu-central-1:123456789012:function:Example',
lambda_function_memory_size: 128,
lambda_function_name: 'foo-bar-function',
level: 'WARN',
message: 'This is a WARN log',
service: 'hello-world',
timestamp: '2021-03-13T18:11:46.919Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
{
aws_request_id: 'c6af9ac6-7b61-11e6-9a41-93e812345678',
cold_start: true,
lambda_function_arn: 'arn:aws:lambda:eu-central-1:123456789012:function:Example',
lambda_function_memory_size: 128,
lambda_function_name: 'foo-bar-function',
level: 'ERROR',
message: 'This is an ERROR log',
service: 'hello-world',
timestamp: '2021-03-13T18:11:46.921Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
With the addContext method:
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'INFO';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
const logger = new Logger();
const lambdaHandler: Handler = async () => {
logger.addContext(context);
logger.info('This is an INFO log');
return {
foo: 'bar'
};
};Click to expand and see the logs outputs
{
cold_start: true,
function_arn: 'arn:aws:lambda:eu-central-1:123456789012:function:foo-bar-function',
function_memory_size: 128,
function_request_id: 'c6af9ac6-7b61-11e6-9a41-93e812345678',
function_name: 'foo-bar-function',
level: 'INFO',
message: 'This is an INFO log',
service: 'hello-world',
timestamp: '2021-12-15T23:56:17.773Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
With decorators:
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'INFO';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
const logger = new Logger();
class Lambda implements LambdaInterface {
@logger.injectLambdaContext()
public handler<TEvent, TResult>(_event: TEvent, _context: Context, _callback: Callback<TResult>): void | Promise<TResult> {
logger.info('This is an INFO log with some context');
}
}
new Lambda().handler(dummyEvent, dummyContext, () => console.log('Lambda invoked!'));Click to expand and see the logs outputs
{
cold_start: true,
function_arn: 'arn:aws:lambda:eu-central-1:123456789012:function:foo-bar-function',
function_memory_size: 128,
function_request_id: 'c6af9ac6-7b61-11e6-9a41-93e812345678',
function_name: 'foo-bar-function',
level: 'INFO',
message: 'This is an INFO log with some context',
service: 'hello-world',
timestamp: '2021-12-15T23:57:25.749Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'INFO';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
const logger = new Logger();
const lambdaHandler: Handler = async () => {
const myImportantVariable = {
foo: 'bar'
};
// Pass a variable
logger.info('This is a log with an extra variable', { data: { myImportantVariable } });
// Pass a variable
const myOtherImportantVariable = {
biz: 'baz'
};
// Pass multiple variables
logger.info('This is a log with 2 extra variables', {
data: { myOtherImportantVariable },
correlationIds: { myCustomCorrelationId: 'foo-bar-baz' }
});
return {
foo: 'bar'
};
};
Click to expand and see the logs outputs
{
level: 'INFO',
message: 'This is a log with an extra variable',
service: 'hello-world',
timestamp: '2021-03-25T09:30:55.097Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456',
data: { myImportantVariable: { foo: 'bar' } }
}
{
level: 'INFO',
message: 'This is a log with 2 extra variables',
service: 'hello-world',
timestamp: '2021-03-25T09:30:55.102Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456',
data: { myOtherImportantVariable: { biz: 'baz' } },
correlationIds: { myCustomCorrelationId: 'foo-bar-baz' }
}
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'WARN';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
const logger = new Logger();
const lambdaHandler: Handler = async () => {
try {
throw new Error('Unexpected error #1');
} catch (error) {
logger.error('This is an ERROR log #1', error);
}
try {
throw new Error('Unexpected error #2');
} catch (error) {
logger.error('This is an ERROR log #2', { myCustomErrorKey: error } );
}
return {
foo: 'bar'
};
};Click to expand and see the logs outputs
{
level: 'ERROR',
message: 'This is an ERROR log #1',
service: 'hello-world',
timestamp: '2021-03-25T10:55:46.590Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456',
error: {
name: 'Error',
location: '/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:19',
message: 'Unexpected error #1',
stack: 'Error: Unexpected error #1\n' +
' at lambdaHandler (/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:19:11)\n' +
' at Object.<anonymous> (/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:36:1)\n' +
' at Module._compile (node:internal/modules/cjs/loader:1108:14)\n' +
' at Module.m._compile (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/index.ts:1056:23)\n' +
' at Module._extensions..js (node:internal/modules/cjs/loader:1137:10)\n' +
' at Object.require.extensions.<computed> [as .ts] (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/index.ts:1059:12)\n' +
' at Module.load (node:internal/modules/cjs/loader:973:32)\n' +
' at Function.Module._load (node:internal/modules/cjs/loader:813:14)\n' +
' at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:76:12)\n' +
' at main (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/bin.ts:198:14)'
}
}
{
level: 'ERROR',
message: 'This is an ERROR log #2',
service: 'hello-world',
timestamp: '2021-03-25T10:55:46.624Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456',
myCustomErrorKey: {
name: 'Error',
location: '/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:25',
message: 'Unexpected error #2',
stack: 'Error: Unexpected error #2\n' +
' at lambdaHandler (/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:25:11)\n' +
' at Object.<anonymous> (/projects/aws-lambda-powertools-typescript/packages/logger/examples/errors.ts:36:1)\n' +
' at Module._compile (node:internal/modules/cjs/loader:1108:14)\n' +
' at Module.m._compile (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/index.ts:1056:23)\n' +
' at Module._extensions..js (node:internal/modules/cjs/loader:1137:10)\n' +
' at Object.require.extensions.<computed> [as .ts] (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/index.ts:1059:12)\n' +
' at Module.load (node:internal/modules/cjs/loader:973:32)\n' +
' at Function.Module._load (node:internal/modules/cjs/loader:813:14)\n' +
' at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:76:12)\n' +
' at main (/projects/aws-lambda-powertools-typescript/packages/logger/node_modules/ts-node/src/bin.ts:198:14)'
}
}
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'INFO';
const parentLogger = new Logger();
const childLogger = parentLogger.createChild({
logLevel: 'ERROR'
});
const lambdaHandler: Handler = async () => {
parentLogger.info('This is an INFO log, from the parent logger');
parentLogger.error('This is an ERROR log, from the parent logger');
childLogger.info('This is an INFO log, from the child logger');
childLogger.error('This is an ERROR log, from the child logger');
return {
foo: 'bar'
};
};Click to expand and see the logs outputs
{
level: 'INFO',
message: 'This is an INFO log, from the parent logger',
service: 'hello-world',
timestamp: '2021-03-25T09:34:06.652Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
{
level: 'ERROR',
message: 'This is an ERROR log, from the parent logger',
service: 'hello-world',
timestamp: '2021-03-25T09:34:06.656Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
{
level: 'ERROR',
message: 'This is an ERROR log, from the child logger',
service: 'hello-world',
timestamp: '2021-03-25T09:34:06.656Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456'
}
// Environment variables set for the Lambda
process.env.LOG_LEVEL = 'WARN';
process.env.POWERTOOLS_SERVICE_NAME = 'hello-world';
process.env.POWERTOOLS_LOGGER_SAMPLE_RATE = '0.5';
const logger = new Logger();
const lambdaHandler: Handler = async () => {
logger.info('This is INFO log #1');
logger.info('This is INFO log #2');
logger.info('This is INFO log #3');
logger.info('This is INFO log #4');
return {
foo: 'bar'
};
};
const logger = new Logger({
logLevel: 'DEBUG',
serviceName: 'hello-world',
sampleRateValue: 0.5,
persistentLogAttributes: { // Custom attributes that will be added in every log item
awsAccountId: process.env.AWS_ACCOUNT_ID || '123456789012',
logger: {
name: powertool.name,
version: powertool.version,
}
},
});
const lambdaHandler: Handler = async () => {
logger.info('This is an INFO log', { correlationIds: { myCustomCorrelationId: 'foo-bar-baz' } });
return {
foo: 'bar'
};
};Click to expand and see the logs outputs
{
level: 'INFO',
message: 'This is an INFO log',
sampling_rate: 0.5,
service: 'hello-world',
timestamp: '2021-03-25T09:59:31.252Z',
xray_trace_id: 'abcdef123456abcdef123456abcdef123456',
awsAccountId: '123456789012',
logger: { name: 'aws-lambda-powertools-typescript', version: '0.0.1' },
correlationIds: { myCustomCorrelationId: 'foo-bar-baz' }
}
class MyCompanyLogFormatter extends LogFormatter {
public formatAttributes(attributes: UnformattedAttributes): MyCompanyLog {
return {
message: attributes.message,
service: attributes.serviceName,
environment: attributes.environment,
awsRegion: attributes.awsRegion,
correlationIds: {
awsRequestId: attributes.lambdaContext?.awsRequestId,
xRayTraceId: attributes.xRayTraceId
},
lambdaFunction: {
name: attributes.lambdaContext?.functionName,
arn: attributes.lambdaContext?.invokedFunctionArn,
memoryLimitInMB: attributes.lambdaContext?.memoryLimitInMB,
version: attributes.lambdaContext?.functionVersion,
coldStart: attributes.lambdaContext?.coldStart,
},
logLevel: attributes.logLevel,
timestamp: this.formatTimestamp(attributes.timestamp),
logger: {
sampleRateValue: attributes.sampleRateValue,
},
};
}
}const logger = new Logger({
logFormatter: new MyCompanyLogFormatter(), // Custom log formatter to print the log in a custom structure
logLevel: 'DEBUG',
serviceName: 'hello-world',
sampleRateValue: 0.5,
persistentLogAttributes: { // Custom attributes that will be added in every log item
awsAccountId: process.env.AWS_ACCOUNT_ID || '123456789012',
logger: {
name: powertool.name,
version: powertool.version,
}
},
});
const lambdaHandler: Handler = async (event, context) => {
logger.addContext(context);
logger.info('This is an INFO log', { correlationIds: { myCustomCorrelationId: 'foo-bar-baz' } });
return {
foo: 'bar'
};
};Click to expand and see the logs outputs
{
message: 'This is an INFO log',
service: 'hello-world',
awsRegion: 'eu-central-1',
correlationIds: {
awsRequestId: 'c6af9ac6-7b61-11e6-9a41-93e812345678',
xRayTraceId: 'abcdef123456abcdef123456abcdef123456',
myCustomCorrelationId: 'foo-bar-baz'
},
lambdaFunction: {
name: 'foo-bar-function',
arn: 'arn:aws:lambda:eu-central-1:123456789012:function:Example',
memoryLimitInMB: 128,
version: '$LATEST',
coldStart: true
},
logLevel: 'INFO',
timestamp: '2021-03-25T10:00:37.194Z',
logger: {
sampleRateValue: 0.5,
name: 'aws-lambda-powertools-typescript',
version: '0.0.1'
},
awsAccountId: '123456789012'
}