API Bundle Size Limit

TL;DR

The Infra.Api.MaxBundleSize extension enforces a maximum size on the built API Lambda bundle. The default limit is 4.5 MB. If the bundle exceeds the limit the build fails with a clear error; add the extension to webiny.config.tsx to raise (or lower) it.

Default Behavior

By default Webiny enforces a 4.5 MB limit on the API Lambda bundle (handler.mjs). If the built output exceeds this, the build fails:

error   Build errors:
× asset size limit: The following asset(s) exceed the recommended size limit (4.5 MiB).
× entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (4.5 MiB).
error   build failed

Raising the Limit

Add Infra.Api.MaxBundleSize to webiny.config.tsx with size in bytes:

tsx
// webiny.config.tsx
import { Infra } from "webiny/extensions";

export const Extensions = () => (
  <>
    {/* Raise the API bundle size limit to 6 MB */}
    <Infra.Api.MaxBundleSize size={6 * 1024 * 1024} />
  </>
);

Common byte values:

| MB | Bytes expression | Exact bytes | | --- | ------------------------------- | ----------------- | | 4.5 | Math.round(4.5 * 1024 * 1024) | 4718592 (default) | | 5 | 5 * 1024 * 1024 | 5242880 | | 6 | 6 * 1024 * 1024 | 6291456 | | 8 | 8 * 1024 * 1024 | 8388608 | | 10 | 10 * 1024 * 1024 | 10485760 |

How It Works

The extension sets the WEBINY_INFRA_API_MAX_BUNDLE_SIZE environment variable (in bytes) which is read by the API bundler (@webiny/build-tools) at build time. The WEBINY_INFRA_ prefix ensures the variable is not automatically forwarded to the Lambda function's runtime environment.

Lowering the Limit

You can also enforce a stricter limit to catch bundle regressions early:

tsx
{
  /* Enforce a strict 3 MB limit */
}
<Infra.Api.MaxBundleSize size={3 * 1024 * 1024} />;

Quick Reference

| Task | Snippet | | ------------------------ | ----------------------------------------------------- | | Raise to 6 MB | <Infra.Api.MaxBundleSize size={6 * 1024 * 1024} /> | | Raise to 10 MB | <Infra.Api.MaxBundleSize size={10 * 1024 * 1024} /> | | Restore default (4.5 MB) | Remove the extension | | Convert MB to bytes | Math.round(N * 1024 * 1024) |

Related Skills

• infra-env-var -- setting arbitrary environment variables in the project context
• api-lambda-function -- adding custom Lambda functions to the API