Logs in Kubernetes Pod not showing up

Question

I have Kubernetes set up and running a grpc service in a pod. I am successfully hitting an endpoint on the service, which has a print() statement in it, but I see no logs in the log file. I have seen this before when I was running a (cron) job in Kubernetes and the logs only appeared after the job was done (as opposed to when the job was running). Is there a way to make kubernetes write to the log file right away? Any setting that I can put (either cluster-level or just for the pod)? Thanks for any help in advance!

Answer 1

Found the root cause. Specifically, found it at Python app does not print anything when running detached in docker . The solution is to set the following environmental variable: PYTHONUNBUFFERED=0 . It was not that the print statement was not being displayed, it was that the print statement was being buffered. Doing the above will solve the issue.

Answer 2

Here is an example of K8S deployment yaml so you can copy paste the solution from the aforementioned answer:

root@k8s:~/python_docker$ cat deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hpa
spec:
  selector:
    matchLabels:
      app: hpa
  template:
    metadata:
      labels:
        app: hpa
    spec:
      containers:
      - name: hpa
        image: my-hpa/py
        env:
        - name: PYTHONUNBUFFERED
          value: "0"
        resources:
          requests:
            cpu: 100m
            memory: 200Mi