Solve: ECS-CDK Deploys and the Timing Trap—Notes from the Field

Solve: ECS-CDK Deploys and the Timing Trap—Notes from the Field

This isn’t the kind of issue you catch in tutorials. It’s the kind that quietly eats your morning, just when you thought you were ready to deploy.

If you’re rolling out an ECS service using CDK—and you’re creating your infrastructure and container image for the first time—you may run headfirst into a silent conflict between build timing and deploy order. CDK tries to launch the ECS service before your image exists in ECR. That leads to a 404 at the ECS level, and the whole thing rolls back.

At this point, there’s a decision to be made.

Option 1: Pre-Push Your Image

One option is to build and push a placeholder container to ECR before your first CDK deploy. This lets CDK proceed without breaking ECS on image fetch. It’s a manual step, but it clears the dependency deadlock and lets you move forward fast. Later, you can swap in your real image.

Option 2: Deploy in Two Passes

The other approach is more surgical. Deploy the pipeline stack first—without attaching the ECS service—let it go green, and only then attach ECS and re-deploy. This cleanly separates concerns, but it may introduce extra steps in your stack lifecycle.

Both approaches are reasonable—but understanding why this problem occurs and how to handle it clearly is what turns a frustrating block into an intentional architecture choice.

We’ve documented a fully working, tested version of this pattern in a three-part blog series:


Part 1: Why the First Deploy Fails


Part 2: Using a Placeholder Image to Bootstrap ECS


Part 3: Swapping in Your Real Container

Each post includes copy-paste CDK code and plain-English reasoning. No guesswork needed.

If you’re hitting this issue in real-time—this post is your pause point. Make your call. Then go finish the deploy.

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Written by Aaron Rose, software engineer and technology writer at Tech-Reader.blog.