Docker-Kubernets can't find manage.py - django

Question

I built an API in Django and I used docker-compose to orchestrate redis and celery services. Now, I would like to move the API to a Kubernetes cluster (AKS). However, I get the error python can't find manage.py when I run it into the cluster. I used Kompose tool to write the kubernets manifest.yaml. This is my Dockerfile, docker-compose.yml and kubernets.yaml files
# docker-compose.yml
version: '3'
services:
app:
build:
context: .
ports:
- "8000:8000"
volumes:
- ./app:/app
command: >
sh -c "python3 ./manage.py makemigrations &&
python3 ./manage.py migrate &&
python3 ./manage.py runserver 0.0.0.0:8000"
The Dockerfile
# Dockerfile
FROM python:3.8
ENV PYTHONUNBUFFERED 1
COPY ./requirements.txt /requirements.txt
RUN pip install -r /requirements.txt
RUN mkdir /app
COPY ./app /app
WORKDIR /app
And the kubernets manifest
apiVersion: v1
items:
- apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
name: app
spec:
ports:
- name: "8000"
port: 8000
targetPort: 8000
selector:
io.kompose.service: app
status:
loadBalancer: {}
- apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
name: app
spec:
replicas: 1
selector:
matchLabels:
io.kompose.service: app
strategy:
type: Recreate
template:
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
spec:
containers:
- args:
- sh
- -c
- |-
python manage.py makemigrations &&
python manage.py migrate &&
python manage.py runserver 0.0.0.0:8000
image: <image pushed in a Azure Container Registry (ACR)>
name: app
ports:
- containerPort: 8000
resources: {}
volumeMounts:
- mountPath: /app
name: app-claim0
restartPolicy: Always
volumes:
- name: app-claim0
persistentVolumeClaim:
claimName: app-claim0
status: {}
- apiVersion: v1
kind: PersistentVolumeClaim
metadata:
creationTimestamp: null
labels:
io.kompose.service: app-claim0
name: app-claim0
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 100Mi
status: {}
Log error
$ kubectl logs app-6fc488bf56-hb8g9 --previous
# python: can't open file 'manage.py': [Errno 2] No such file or director

Answer 1

I think your problem is with the volumes segment of your kubernetes config.
In your docker-compose config, you have a volume mounting
volumes:
- ./app:/app
This is great for local development because it'll take the copy of the code on your machine and overlay it on the docker image so the changes you make on your machine will be reflected in your running docker container, allowing runserver to see file changes and reload the django server as needed.
This is less great in kubernetes - when you're running in prod, you want to be using the code that's been baked in to the image. As this is currently configured, I think you're creating an empty PersistentVolumeClaim and then mounting it on top of your /app directory in the running container. Since it's empty, there is no manage.py file to be found.
Try making your kubernetes configuration look like this:
apiVersion: v1
items:
- apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
name: app
spec:
ports:
- name: "8000"
port: 8000
targetPort: 8000
selector:
io.kompose.service: app
status:
loadBalancer: {}
- apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
name: app
spec:
replicas: 1
selector:
matchLabels:
io.kompose.service: app
strategy:
type: Recreate
template:
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o kb_manifests.yaml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: app
spec:
containers:
- args:
- sh
- -c
- |-
python manage.py makemigrations &&
python manage.py migrate &&
python manage.py runserver 0.0.0.0:8000
image: <image pushed in a Azure Container Registry (ACR)>
name: app
ports:
- containerPort: 8000
resources: {}
restartPolicy: Always
status: {}
That should be the same as what you have minus any references to volumes.
If that works then you're off to the races. Once it's up and running, take a look at the Django deployment guide about some other settings you should configure - namely, take a look at gunicorn; runserver isn't your best path forward for production deploys.