Deployment fails: nested CloudFormation template for 'data' stack exceeds 1MB (no API to enable Stack.suppressTemplateIndentation)

[fossamagna]

Environment information

System:
  OS: Linux 6.6 Debian GNU/Linux 11 (bullseye) 11 (bullseye)
  CPU: (6) arm64 unknown
  Memory: 4.86 GB / 15.60 GB
  Shell: /bin/bash
Binaries:
  Node: 22.16.0 - /usr/local/bin/node
  Yarn: 1.22.22 - /usr/local/bin/yarn
  npm: 10.9.2 - /usr/local/bin/npm
  pnpm: undefined - undefined
NPM Packages:
  @aws-amplify/auth-construct: 1.8.1
  @aws-amplify/backend: 1.16.1
  @aws-amplify/backend-ai: Not Found
  @aws-amplify/backend-auth: 1.7.1
  @aws-amplify/backend-cli: 1.8.0
  @aws-amplify/backend-data: 1.6.1
  @aws-amplify/backend-deployer: 2.1.3
  @aws-amplify/backend-function: 1.14.1
  @aws-amplify/backend-output-storage: 1.3.1
  @aws-amplify/backend-secret: 1.4.0
  @aws-amplify/backend-storage: 1.4.1
  @aws-amplify/cli-core: 2.2.1
  @aws-amplify/client-config: 1.8.0
  @aws-amplify/data-construct: 1.16.3
  @aws-amplify/data-schema: 1.21.0
  @aws-amplify/deployed-backend-client: 1.8.0
  @aws-amplify/form-generator: 1.2.1
  @aws-amplify/model-generator: 1.2.0
  @aws-amplify/platform-core: 1.10.0
  @aws-amplify/plugin-types: 1.11.0
  @aws-amplify/sandbox: 2.1.2
  @aws-amplify/schema-generator: 1.4.0
  @aws-cdk/toolkit-lib: 1.1.1
  aws-amplify: 6.15.3
  aws-cdk-lib: 2.189.1
  typescript: 5.8.3
No AWS environment variables
No CDK environment variables

Describe the bug

When deploying with npx ampx sandbox, the following error occurs. (xxxxxx is a placeholder because the original value includes the app name and username.)

After checking, the template size for the data stack in
.amplify/artifacts/cdk.out/amplifyxxxxxxsandbox71a64dcc04data71394BCF.nested.template.json
exceeded 1 MB.

I found that CDK’s Stack.suppressTemplateIndentation (https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Stack.html#suppresstemplateindentation) can minify the CloudFormation template JSON. However, amplify-backend does not provide an API to configure this.

Workaround
By forcibly enabling CDK Stack.suppressTemplateIndentation as shown below, the template JSON gets minified:

amplify/backend.ts:

// Suppress indentation changes to the CloudFormation template
backend.data.stack._suppressTemplateIndentation = true;

Reproduction steps

Deploy after increasing the number of resources included in the data stack using the following approach:

• Define many custom queries/mutations in data/resources.ts
• Set "data" as the resourceGroupName for defineFunction

[pahud]

Hi @fossamagna,

Thank you for reporting this issue and providing a clear workaround. This appears to be a valid feature request for exposing CDK's suppressTemplateIndentation configuration through the amplify-backend API.

Currently, the DataFactory creates an AmplifyData construct without providing a way to configure the underlying stack's template indentation behavior. When data schemas grow large with many custom queries, mutations, or functions, the generated CloudFormation template can exceed the 1MB nested template size limit.

Your workaround of setting backend.data.stack._suppressTemplateIndentation = true is accessing a private property, which isn't ideal for long-term maintainability.

A proper solution would involve:

1. Adding a suppressTemplateIndentation option to the DataProps interface
2. Passing this configuration through to the AmplifyData construct
3. Having the AmplifyData construct apply this setting to its internal stack

This would allow users to write:

export const data = defineData({
 schema,
 suppressTemplateIndentation: true
});

Alternatively, the framework could automatically enable template minification for sandbox deployments or when the schema size exceeds a certain threshold.

Making this a p2 FR and we welcome upvotes 👍