How to use @aws-cdk/aws-lambda

constructor(parent, id, props) {
  super(parent, id, props);

  // Create a lambda that recrawls changelogs discovered in the past
  const recrawlLambda = new lambda.Function(this, 'recrawl', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'recrawl.handle',
   code: lambda.Code.asset('./app/recrawl'),
   timeout: cdk.Duration.minutes(5),
   environment: {
    CHANGELOGS_TABLE_NAME: props.changelogsTable.tableName,
    DISCOVERED_TOPIC_NAME: props.toCrawlTopic.topicArn
   }
  });

  // Grant the lambda permission to modify the tables
  props.changelogsTable.grantReadWriteData(recrawlLambda.role);
  props.toCrawlTopic.grantPublish(recrawlLambda.role);

  // Schedule the recrawler to run once every minute
  this.eventRule = new events.Rule(this, 'recrawl-check-schedule', {
   schedule: events.Schedule.rate(cdk.Duration.minutes(1)),
   targets: [new eventTargets.LambdaFunction(recrawlLambda)]
  });
 }

constructor(parent, id, props) {
  super(parent, id, props);

  // Create a lambda that returns autocomplete results
  const autocomplete = new lambda.Function(this, 'autocomplete', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'autocomplete.handle',
   code: lambda.Code.asset('./app/autocomplete'),
   environment: {
    SEARCH_INDEX_TABLE_NAME: props.searchIndexTable.tableName
   }
  });

  // Grant the lambda permission to modify the tables
  props.searchIndexTable.grantReadWriteData(autocomplete.role);

  this.autocompleteGateway = new apiGateway.LambdaRestApi(this, 'autocomplete-gateway', {
   handler: autocomplete,
   proxy: true
  });

  this.url = this.autocompleteGateway.url;
 }

const regenerateHomepage = new lambda.Function(this, 'regenerate-homepage', {
 runtime: lambda.Runtime.NODEJS_12_X,
 handler: 'regenerate-homepage.handle',
 code: lambda.Code.asset('./app/regenerate-homepage'),
 environment: {
  CHANGELOGS_TABLE_NAME: props.changelogsTable.tableName,
props.feedsTable.grantReadData(regenerateHomepage.role);
props.changelogsTable.grantReadData(regenerateHomepage.role);
props.webBucket.grantReadWrite(regenerateHomepage.role);

const lambdaFn = new lambda.Function(this, lambdaName, {
 functionName: lambdaName,
 code: lambda.Code.asset('src'),
 handler: 'handler.main',
 timeout: cdk.Duration.seconds(300),
 runtime: lambda.Runtime.NODEJS_10_X,
 environment: {
  DATA_BUCKET: `${bucket.bucketName}`,

constructor(parent, id, props) {
  super(parent, id, props);

  // Create a lambda that returns autocomplete results
  const recentlyCrawled = new lambda.Function(this, 'recently-crawled', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'recently-crawled.handle',
   code: lambda.Code.asset('./app/recently-crawled'),
   environment: {
    FEEDS_TABLE_NAME: props.feedsTable.tableName,
    API_BUCKET_NAME: props.apiBucket.bucketName
   }
  });

  // Grant the lambda permission to modify the tables and S3 bucket
  props.feedsTable.grantReadWriteData(recentlyCrawled.role);
  props.apiBucket.grantReadWrite(recentlyCrawled.role);

  // Schedule the recrawler to run once every minute
  this.eventRule = new events.Rule(this, 'recrawl-check-schedule', {
   schedule: events.Schedule.rate(cdk.Duration.minutes(1)),
   targets: [new eventTargets.LambdaFunction(recentlyCrawled)]
  });
 }

const crawlLambda = new lambda.Function(this, 'crawl-lambda', {
 runtime: lambda.Runtime.NODEJS_12_X,
 handler: 'crawl.handle',
 code: lambda.Code.asset('./app/crawl'),
 timeout: cdk.Duration.seconds(30),
 vpc: props.vpc,
crawlLambda.addEventSource(crawlEventSource);
props.changelogsTable.grantReadWriteData(crawlLambda.role);
props.feedsTable.grantReadWriteData(crawlLambda.role);
props.searchIndexTable.grantReadWriteData(crawlLambda.role);
props.webBucket.grantReadWrite(crawlLambda.role);
props.apiBucket.grantReadWrite(crawlLambda.role);
crawlLambda.connections.allowToDefaultPort(props.redis);

constructor(parent, id, props) {
  super(parent, id, props);

  // Create the lambda
  const pypiFollower = new lambda.Function(this, 'pypi-follower', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'pypi-recent.handle',
   code: lambda.Code.asset('./app/pypi-recent'),
   timeout: cdk.Duration.minutes(1),
   environment: {
    CHANGELOGS_TABLE_NAME: props.changelogsTable.tableName,
    DISCOVERED_TOPIC_NAME: props.toCrawlTopic.topicArn
   }
  });

  // Grant this application access to the DynamoDB table and SNS topic
  props.changelogsTable.grantReadWriteData(pypiFollower.role);
  props.toCrawlTopic.grantPublish(pypiFollower.role);

  // Schedule the follower to run once every 5 mins
  this.eventRule = new events.Rule(this, 'check-recent-pypi', {
   schedule: events.Schedule.rate(cdk.Duration.minutes(5)),
   targets: [new eventTargets.LambdaFunction(pypiFollower)]
  });
 }

constructor(parent, id, props) {
  super(parent, id, props);

  // Create the lambda
  const rubygemFollower = new lambda.Function(this, 'rubygem-follower', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'rubygem-recent.handle',
   code: lambda.Code.asset('./app/rubygem-recent'),
   timeout: cdk.Duration.minutes(1),
   environment: {
    CHANGELOGS_TABLE_NAME: props.changelogsTable.tableName,
    DISCOVERED_TOPIC_NAME: props.toCrawlTopic.topicArn
   }
  });

  // Grant this application access to the DynamoDB table and SNS topic
  props.changelogsTable.grantReadWriteData(rubygemFollower.role);
  props.toCrawlTopic.grantPublish(rubygemFollower.role);

  // Schedule the follower to run once every 5 mins
  this.eventRule = new events.Rule(this, 'check-recent-rubygems', {
   schedule: events.Schedule.rate(cdk.Duration.minutes(5)),
   targets: [new eventTargets.LambdaFunction(rubygemFollower)]
  });
 }