Automate Post-Deployment Tasks with `cdkTrigger` in AWS CDK

Deploying infrastructure with AWS CDK is powerful — but sometimes, you want something more than just resources in place. Maybe you want to:

• Seed a database after deployment
• Populate an S3 bucket with default data
• Kick off a workflow
• Or simply validate that everything deployed successfully

That's where the cdk-triggers module comes in. In this post, we'll walk through how to use cdk.triggers.Trigger to automatically invoke a Lambda function after a successful CDK deployment.

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🔧 What is cdk.triggers.Trigger?

The Trigger construct is part of the aws-cdk-lib.triggers module. It allows you to run a Lambda automatically after your stack is deployed — great for bootstrapping and post-deploy configuration tasks.

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🧪 Example: Run a Lambda After Resources Are Created

Let’s say you’re deploying:

• An S3 bucket
• A DynamoDB table
• A Lambda that seeds a database

You want the Lambda to run after all the resources are successfully created.

Step 1: Import Required Modules

import * as cdk from "aws-cdk-lib";
import * as lambda from "aws-cdk-lib/aws-lambda";
import * as s3 from "aws-cdk-lib/aws-s3";
import * as dynamodb from "aws-cdk-lib/aws-dynamodb";
import * as triggers from "aws-cdk-lib/triggers";
import { Construct } from "constructs";

Step 2: Define the Stack

export class MyStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // S3 bucket
    const bucket = new s3.Bucket(this, "MyBucket");

    // DynamoDB table
    const table = new dynamodb.Table(this, "MyTable", {
      partitionKey: { name: "id", type: dynamodb.AttributeType.STRING },
    });

    // Lambda function to run post-deploy
    const seedFunction = new lambda.Function(this, "SeedFunction", {
      runtime: lambda.Runtime.NODEJS_18_X,
      handler: "index.handler",
      code: lambda.Code.fromAsset("lambda/seed"),
      timeout: cdk.Duration.minutes(5),
      environment: {
        BUCKET_NAME: bucket.bucketName,
        TABLE_NAME: table.tableName,
      },
    });

    bucket.grantReadWrite(seedFunction);
    table.grantReadWriteData(seedFunction);

    // Create the trigger
    const cdkTrigger = new triggers.Trigger(this, "SeedTrigger", {
      handler: seedFunction,
      timeout: cdk.Duration.minutes(10),
      invocationType: triggers.InvocationType.EVENT, // async invocation
    });

    // Define dependencies – only run trigger after these resources are created
    cdkTrigger.executeAfter(bucket);
    cdkTrigger.executeAfter(table);
  }
}

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🔁 How It Works

During deployment, CDK will:

1. Deploy your stack’s resources (bucket, table, Lambda).
2. Automatically invoke the seedFunction via the trigger.
3. Ensure it runs only once (unless you opt to re-run it).

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🛠 Notes & Best Practices

• The Trigger construct deploys a custom resource under the hood.

• The invocationType can be:

  • EVENT: Asynchronous (default and recommended for non-critical background jobs)
  • REQUEST_RESPONSE: Wait for result (useful for critical tasks, but can cause stack rollback on failure)

• You can use cdkTrigger.executeAfter(...) to control execution order and guarantee your resources are ready.

• To re-run the trigger every deploy, set cdkTrigger.trigger.runOnUpdate = true.

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🧹 Optional: Clean Up After Execution

By default, the Lambda and the trigger stay in place. If you want to clean up the Lambda after running:

cdkTrigger.applyRemovalPolicy(cdk.RemovalPolicy.DESTROY);

Or consider separating your post-deployment logic into a one-time stack.

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✅ Summary

cdk.triggers.Trigger is a great way to kick off post-deployment automation in a clean, repeatable way.

Use it to:

• Seed databases
• Initialize state
• Validate configs
• Or automate any once-per-deploy logic

No need for separate scripts or manual steps — just CDK.

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📁 Example Directory Structure

my-app/
├── bin/
│   └── my-app.ts
├── lib/
│   └── my-stack.ts
├── lambda/
│   └── seed/
│       └── index.ts

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🧪 Want to Try It?

Make sure you have the triggers module installed:

npm install aws-cdk-lib constructs

That’s it! Happy automating with CDK! ⚙️