I’m new to using Google Cloud Run (GCR) and facing an issue where my application hosted on GCR (app1) is unable to receive a response from a service hosted on Google Kubernetes Engine (GKE, app2), despite logs on GKE showing a successful handling of requests with a 200 status code.

Issue Description

• App1 (GCR): Sends a GET request to App2 (GKE), using its external ip.
• App2 responds with a 200 status code, as confirmed by GKE logs. But it seems that the response never delivered back.
• App1 waits for 30 seconds and then times out with a 503 error, indicating a “malformed HTTP response or connection error”

Steps Taken

1. Deployed App1 on GKE where it successfully sends requests and receives responses. It works locally as well. We will use this version if we can’t deal with GCR. But i really want to understand what is the problem with GCR.
2. Changed the Gunicorn timeout setting from the default 30 seconds to 1 and 3 minutes. And app is getting silent fot the 1m,3m and then gets 503 error again.
3. Added logging to App1:

   logger.info(f'App is ready to send GET request to {app_url}')
   response = requests.get(app_url, headers=headers)
   logger.info(f'GET request sent to {app_url}')
   

App1 on GCR logs only “App is ready to send GET request” and nothing thereafter.
App1 on GKE logs the receipt and response to the request.

Honestly, i don’t have any ideas whats going wrong with GCR app and how to debug it. Will be grateful for your ideas and help.