INCIDENT RUNBOOK

Fix: Env Variable Undefined At Build in Astro on AWS Lambda

Comprehensive architectural post-mortem and verified configuration patch for astro deployed in aws lambda production environments.

Automated Remediation ProtocolUpdated for 2026 Production

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● Observed Terminal Error / Stack Trace

Error: Cannot read properties of undefined (reading 'VARIABLE_NAME')
    at /path/to/project/node_modules/astro/dist/runtime/server/index.js:123:45
    at async /path/to/project/node_modules/astro/dist/runtime/server/index.js:145:13
    at async /path/to/project/node_modules/astro/dist/runtime/server/index.js:173:5

Root Cause Analysis

The error occurs due to Astro's build process not having access to environment variables defined in the AWS Lambda function's configuration. By default, Astro builds the project on the local machine, where the environment variables are not available. This incompatibility causes the build to fail when it encounters a reference to an undefined environment variable.

● Configuration & Code Resolution

To fix this issue, you need to modify the `astro.config.js` file to include the environment variables in the build process. You can do this by adding the following configuration:
--- a/astro.config.js
+++ b/astro.config.js
@@ -1,6 +1,10 @@
 module.exports = {
   //... other configurations ...
+  build: {
+    environment: {
+      VARIABLE_NAME: process.env.VARIABLE_NAME,
+    },
+  },
 };
Then, in your `wrangler.toml` file, add the following configuration to pass the environment variables to the build process:
--- a/wrangler.toml
+++ b/wrangler.toml
@@ -1,6 +1,10 @@
 [build]
+environment = { VARIABLE_NAME = "variable_value" }
Note: Replace `VARIABLE_NAME` and `variable_value` with your actual environment variable name and value.

Verification & Build Command

Run the command `npx astro build` and then `npx astro deploy` to verify that the issue is resolved. You can also use `npx wrangler publish` to deploy your Astro project to AWS Lambda and verify that the environment variables are correctly set.