How to Fix Cold Start Issues on AWS Lambda (Node.js 22.x)

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Are you facing issues with HTTPS requests failing in your Lambda function? Here’s a simple step-by-step guide to troubleshoot and resolve these problems.

First, understand that when your Lambda starts without reserved concurrency, it has a “cold start,” meaning it takes a bit longer to initialize. During this start, your function successfully contacts Auth0 and gets a bearer token, then it tries to make a request to your GraphQL API using that token. If the same setup works in Postman, but not in Lambda, the problem is likely related to how the request is made or how Lambda handles network connections.

You’ve already tested different methods like node-fetch, axios, and raw HTTPS requests. Despite this, the Lambda logs show that the request begins but then suddenly stops—no further logs appear after the point where the request is awaited in your code. Even though your Lambda is set with a 30-second timeout, it terminates after about 3–4 seconds with a 200 status code, which suggests it’s ending prematurely.

Here’s what you can do to fix this:

Add Detailed Logging:
Make sure your code logs each step—when the request starts, when it ends, and any response or error received. This will give you a clearer idea of where it stalls.
Check for External API Limits:
The GraphQL API might have rate limits. When you keep clicking “Test” in the Lambda UI, it sometimes returns a 404 error instead of the expected data. This could mean you’re hitting a rate limit or there’s an API change. Confirm with the API provider whether there are restrictions, and see if your requests are within the allowed limits.
Verify Network Configuration:
Lambda functions might require specific network settings, especially if the API is inside a private VPC or has IP restrictions. Double-check your Lambda’s network setup and security groups.
Review Request Headers and Payload:
Ensure your request headers, especially the Authorization token, are correctly formatted and up-to-date. Any mismatch can cause the API to reject the request.
Test with Smaller Steps:
Break down your request. First, try obtaining the auth token and logging it. Then, make a simple GET or POST request separately and log the response. This helps isolate whether the problem is with token retrieval or the API call itself.
Adjust Timeout Settings:
Although your Lambda has a 30-second timeout, setting a longer timeout for your HTTP client (like axios) can help prevent early termination if the request simply takes longer due to network latency.
Handle Errors Gracefully:
Wrap your requests in try-catch blocks. Log any errors you catch. Sometimes the actual issue is hidden in the error message.

By following these steps, you should be able to identify if the requests are getting blocked, timing out, or if there’s an issue with the API itself. Troubleshooting network requests in Lambda can be tricky, but systematically checking each part usually reveals the root cause.