CDK Constructs for AWS Lambda
Project description
AWS Lambda Construct Library
This construct library allows you to define AWS Lambda Functions.
import lambda = require('@aws-cdk/aws-lambda');
import path = require('path');
const fn = new lambda.Function(this, 'MyFunction', {
runtime: lambda.Runtime.NODEJS_10_X,
handler: 'index.handler',
code: lambda.Code.fromAsset(path.join(__dirname, 'lambda-handler')),
});
Handler Code
The lambda.Code
class includes static convenience methods for various types of
runtime code.
lambda.Code.fromBucket(bucket, key[, objectVersion])
- specify an S3 object that contains the archive of your runtime code.lambda.Code.fromInline(code)
- inline the handle code as a string. This is limited to supported runtimes and the code cannot exceed 4KiB.lambda.Code.fromAsset(path)
- specify a directory or a .zip file in the local filesystem which will be zipped and uploaded to S3 before deployment.
The following example shows how to define a Python function and deploy the code
from the local directory my-lambda-handler
to it:
new lambda.Function(this, 'MyLambda', {
code: lambda.Code.fromAsset(path.join(__dirname, 'my-lambda-handler')),
handler: 'index.main',
runtime: lambda.Runtime.PYTHON_3_6
});
When deploying a stack that contains this code, the directory will be zip archived and then uploaded to an S3 bucket, then the exact location of the S3 objects will be passed when the stack is deployed.
During synthesis, the CDK expects to find a directory on disk at the asset directory specified. Note that we are referencing the asset directory relatively to our CDK project directory. This is especially important when we want to share this construct through a library. Different programming languages will have different techniques for bundling resources into libraries.
Layers
The lambda.LayerVersion
class can be used to define Lambda layers and manage
granting permissions to other AWS accounts or organizations.
const layer = new lambda.LayerVersion(stack, 'MyLayer', {
code: lambda.Code.fromAsset(path.join(__dirname, 'layer-code')),
compatibleRuntimes: [lambda.Runtime.NODEJS_8_10],
license: 'Apache-2.0',
description: 'A layer to test the L2 construct',
});
// To grant usage by other AWS accounts
layer.addPermission('remote-account-grant', { accountId: awsAccountId });
// To grant usage to all accounts in some AWS Ogranization
// layer.grantUsage({ accountId: '*', organizationId });
new lambda.Function(stack, 'MyLayeredLambda', {
code: new lambda.InlineCode('foo'),
handler: 'index.handler',
runtime: lambda.Runtime.NODEJS_8_10,
layers: [layer],
});
Event Rule Target
You can use an AWS Lambda function as a target for an Amazon CloudWatch event rule:
import targets = require('@aws-cdk/aws-events-targets');
rule.addTarget(new targets.LambdaFunction(myFunction));
Event Sources
AWS Lambda supports a variety of event sources.
In most cases, it is possible to trigger a function as a result of an event by
using one of the add<Event>Notification
methods on the source construct. For
example, the s3.Bucket
construct has an onEvent
method which can be used to
trigger a Lambda when an event, such as PutObject occurs on an S3 bucket.
An alternative way to add event sources to a function is to use function.addEventSource(source)
.
This method accepts an IEventSource
object. The module @aws-cdk/aws-lambda-event-sources
includes classes for the various event sources supported by AWS Lambda.
For example, the following code adds an SQS queue as an event source for a function:
import { SqsEventSource } from '@aws-cdk/aws-lambda-event-sources';
fn.addEventSource(new SqsEventSource(queue));
The following code adds an S3 bucket notification as an event source:
import { S3EventSource } from '@aws-cdk/aws-lambda-event-sources';
fn.addEventSource(new S3EventSource(bucket, {
events: [ s3.EventType.OBJECT_CREATED, s3.EventType.OBJECT_DELETED ],
filters: [ { prefix: 'subdir/' } ] // optional
}));
See the documentation for the @aws-cdk/aws-lambda-event-sources module for more details.
Lambda with DLQ
A dead-letter queue can be automatically created for a Lambda function by
setting the deadLetterQueueEnabled: true
configuration.
import lambda = require('@aws-cdk/aws-lambda');
const fn = new lambda.Function(this, 'MyFunction', {
runtime: lambda.Runtime.NODEJS_8_10,
handler: 'index.handler',
code: lambda.Code.fromInline('exports.handler = function(event, ctx, cb) { return cb(null, "hi"); }'),
deadLetterQueueEnabled: true
});
It is also possible to provide a dead-letter queue instead of getting a new queue created:
import lambda = require('@aws-cdk/aws-lambda');
import sqs = require('@aws-cdk/aws-sqs');
const dlq = new sqs.Queue(this, 'DLQ');
const fn = new lambda.Function(this, 'MyFunction', {
runtime: lambda.Runtime.NODEJS_8_10,
handler: 'index.handler',
code: lambda.Code.fromInline('exports.handler = function(event, ctx, cb) { return cb(null, "hi"); }'),
deadLetterQueue: dlq
});
See the AWS documentation to learn more about AWS Lambdas and DLQs.
Lambda with X-Ray Tracing
import lambda = require('@aws-cdk/aws-lambda');
const fn = new lambda.Function(this, 'MyFunction', {
runtime: lambda.Runtime.NODEJS_8_10,
handler: 'index.handler',
code: lambda.Code.fromInline('exports.handler = function(event, ctx, cb) { return cb(null, "hi"); }'),
tracing: lambda.Tracing.ACTIVE
});
See the AWS documentation to learn more about AWS Lambda's X-Ray support.
Lambda with Reserved Concurrent Executions
import lambda = require('@aws-cdk/aws-lambda');
const fn = new lambda.Function(this, 'MyFunction', {
runtime: lambda.Runtime.NODEJS_8_10,
handler: 'index.handler',
code: lambda.Code.fromInline('exports.handler = function(event, ctx, cb) { return cb(null, "hi"); }'),
reservedConcurrentExecutions: 100
});
See the AWS documentation managing concurrency.
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