@seek/aws-codedeploy-infra


[AWS CDK] infrastructure for AWS CodeDeploy Hooks.

[AWS CDK]: https://docs.aws.amazon.com/cdk/v2/guide/work-with-cdk-typescript.html

Setup

AWS Lambda hooks can be deployed inline with each application in a self-contained [CloudFormation stack],
however this overhead becomes less desirable as you scale to multiple applications.

[CloudFormation stack]: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/stacks.html

The HookStack construct defines a consolidated infrastructure stack that can be deployed once per environment and utilised by multiple applications in the network:

``typescript
import { HookStack } from '@seek/aws-codedeploy-infra';
import { App } from 'aws-cdk-lib';

const app = new App();

new HookStack(app);

app.synth();
`

Usage

$3

In a CDK stack:

`diff
+ import { LambdaDeployment } from '@seek/aws-codedeploy-infra';
import { aws_lambda_nodejs } from 'aws-cdk-lib';

const lambdaFunction = new aws_lambda_nodejs.NodejsFunction(this, 'Function', {
// ...
});

+ const lambdaDeployment = new LambdaDeployment(this, 'Deployment', {
+ lambdaFunction,
+ });

- lambdaFunction.addEventSource(source);
+ lambdaDeployment.alias.addEventSource(source);
`

The LambdaDeployment construct creates a CodeDeploy application and deployment group for your Lambda function,
and applies an aws-codedeploy-hooks tag to enable AWS Lambda hooks to [access these resources].

A BeforeAllowTraffic hook is registered to check that an incoming Lambda function version is healthy before cutting traffic over to its Live alias [all at once].
The hook invokes the incoming Lambda function version with a "smoke test" payload that looks like so:

`typescript
import assert from 'assert';

export const handler = (event: Event, ctx: Context) => {
// An empty event object {}
assert.strictEqual(Object.keys(event).length, 0);

// A context object with a custom user agent prop
assert.strictEqual(
typeof ctx.clientContext?.Custom?.['user-agent'],
'string',
);
};
`

This payload can be recognised by the [isLambdaHook] runtime helper.

[access these resources]: https://docs.aws.amazon.com/IAM/latest/UserGuide/introduction_attribute-based-access-control.html
[all at once]: https://docs.aws.amazon.com/codedeploy/latest/userguide/deployment-configurations.html#deployment-configurations-predefined-lambda
[isLambdaHook`]: ../hooks/README.md#islambdahook