GCP Auto Sends GET Request to Cloud Function After Deployment (onCall Function Using POST)

[phucnguyen]

Hi everyone,

I recently deployed a Firebase Cloud Function using onCall, which is designed to handle only POST requests. However, after deployment, GCP automatically sends a GET request to the function, resulting in the following error:
Error: Invalid request, unable to process.
Request has invalid method: GET

Issue:

The function only accepts POST requests as expected for an onCall function.

However, after deployment, GCP (or Firebase) sends an automatic GET request, which causes an error.

This behavior leads to unnecessary errors in logs.

Questions:
Is there official documentation stating that GCP/Firebase sends a GET request for health checks after deployment?

How can I properly handle or prevent these automatic GET requests from causing errors?

Is there a way to configure Cloud Functions or Firebase to avoid logging this error?

[-Rhett]

Hi @phucnguyen,

Welcome to the Google Cloud Community!

To help me understand the issue better, could you share more details like screenshots, logs, or your function’s code?

Just a heads up, there are slight differences between using functions on Firebase compared to the Google Cloud Platform (GCP). On GCP, functions are deployed using Cloud Run functions, which has two versions (Cloud Run functions and Cloud functions). On Firebase, functions are deployed using Cloud functions for Firebase. These two products offer similar features and should be mutually compatible. For more information, see Cloud Run functions and Firebase or Firebase & Google Cloud.

Is there official documentation stating that GCP/Firebase sends a GET request for health checks after deployment?

I wasn’t able to find an exact article related to function health checks, however this issue thread on the Firebase GitHub might help.

---

How can I properly handle or prevent these automatic GET requests from causing errors?

---

The best way to handle unexpected GET requests to an onCall Firebase Cloud Function is to modify your function's code to explicitly check for and respond to GET requests to prevent errors.

Is there a way to configure Cloud Functions or Firebase to avoid logging this error?

---

Depending on the product you decide to use, see either Monitor your Cloud Run function or Write and view logs.

I also found these related threads that may help with the issue:

• Testing HTTP callable Firebase functions locally
• Can't request, it shows 'Invalid request, unable to process.' and return 'Bad Request'

Was this helpful? If so, please accept this answer as “Solution”. If you need additional assistance, reply here within 2 business days and I’ll be happy to help.