Logs in Kubernetes Pod not showing up

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.

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.ymlapiVersion: apps/v1kind: Deploymentmetadata:  name: hpaspec:  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

One possibility is that the container is starved for CPU. We have run into this issue when running locally on minikube with resource limits that enforced in our larger cluster. Try bumping the CPU resource limits on your pod. Below is an example yaml.

If your CPU limits are around 20-40m, that might be too low to run a full flask/python app. You might try bumping it to closer to 100m. It's not going to crush your local machine.

apiVersion: apps/v1kind: Deploymentmetadata:  name: python-appspec:  selector:    matchLabels:      app: python-app  template:    metadata:      labels:        app: python-app    spec:      containers:      - name: python-app        image: python-app        imagePullPolicy: Never        resources:          requests:            cpu: 40m            memory: 40Mi          limits:            cpu: 20m            memory: 20Mi