INCIDENT RUNBOOK
Fix: Bundle Size Exceeded Worker Limit in Astro on Fly.io
Comprehensive architectural post-mortem and verified configuration patch for astro deployed in fly.io production environments.
Automated Remediation ProtocolUpdated for 2026 Production
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● Observed Terminal Error / Stack Trace
Error: bundle size exceeded worker limit (50MB). Bundle size: 67.3MB. Error code: WORKER_LIMIT_EXCEEDED. Error message: The worker bundle size exceeds the allowed limit.
Root Cause Analysis
The Astro framework is designed to optimize server-side rendering and static site generation, which can lead to large bundle sizes when deployed on Fly.io. The error occurs because the default worker limit on Fly.io is set to 50MB, and the Astro bundle exceeds this limit. This incompatibility arises from the fact that Astro's server-side rendering and static site generation capabilities require a larger codebase, which increases the bundle size.
● Configuration & Code Resolution
To fix this issue, update the `fly.toml` file to increase the worker limit. Add the following configuration to the `[build]` section: `worker_limit = 100MB`. Additionally, optimize the Astro configuration by adding the following to the `astro.config.js` file: `export default { build: { target: 'webworker' } };`. Finally, update the `wrangler.toml` file to include the following configuration: `[build] command = 'npm run build'`Verification & Build Command
Run the command `fly deploy --verbose` to redeploy the application and verify that the error has been resolved. Additionally, use the command `fly info` to check the worker limit and ensure it has been updated correctly.