I have a Django app that i previously was running using docker-compose that I am trying to test on MicroK8s. I used kompose to convert the docker-compose config to kubernetes.
This is the deployment definition.
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f ../docker-compose.yml
kompose.version: 1.31.2 (a92241f79)
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
kompose.version: 1.31.2 (a92241f79)
creationTimestamp: null
labels:
io.kompose.network/bulabuy-build-default: "true"
io.kompose.service: app
spec:
containers:
- args:
- sh
- -c
- |-
python manage.py wait_for_db &&
python manage.py migrate &&
python manage.py runserver 0.0.0.0:8000
env:
- name: DB_HOST
value: db
- name: DB_NAME
value: devdb
- name: DB_PASSWORD
value: password
- name: DB_USER
value: devuser
- name: SELENIUM_HOST
value: selenium-custom
- name: SELENIUM_PORT
value: "5000"
image: bulabuy-build-app
imagePullPolicy: Never
name: app
ports:
- containerPort: 8000
hostPort: 8000
protocol: TCP
resources: {}
volumeMounts:
- mountPath: /vol/web
name: dev-static-data
restartPolicy: Always
volumes:
- name: dev-static-data
persistentVolumeClaim:
claimName: dev-static-data
status: {}
This is the service definition:
apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f ../docker-compose.yml
kompose.version: 1.31.2 (a92241f79)
creationTimestamp: null
labels:
io.kompose.service: app
name: app
spec:
ports:
- name: "8000"
port: 8000
targetPort: 8000
selector:
io.kompose.service: app
status:
loadBalancer: {}
This the output from the pods status (app-577dc6d4f4-cjcdw is the django app):
!Pods status: (https://i.sstatic.net/O3mpU.png)
This is the output from the service status: !Services status: (https://i.sstatic.net/iv6nh.png)
I tried to access the pod to run some checks on the app..
microk8s kubectl exec app-577dc6d4f4-cjcdw -- bash
This resulted in the following error:
Error from server: error dialing backend: tls: failed to verify certificate: x509: certificate is valid for 192.168.1.72, 172.20.0.1, 172.17.0.1, 172.18.0.1, 172.23.0.1, 172.22.0.1, 172.19.0.1, not 192.168.192.225
I also changed the service definition in the spec section to set type to NodePort and still could not access the app on the ip address listed in services.
I am not too sure what I am missing!. Any help with directions is appreciated.
I managed to get it to work. I cleaned up the deployment manifest for the django app.
apiVersion: apps/v1
kind: Deployment
metadata:
name: build-api
spec:
selector:
matchLabels:
app: build-api
replicas: 1
template:
metadata:
labels:
app: build-api
spec:
containers:
- name: build-api
image: bulabuy-api
imagePullPolicy: Never
ports:
- containerPort: 8000
env:
- name: DB_HOST
value: $(DEV_DB_SERVICE_SERVICE_HOST)
- name: DB_NAME
value: devdb
- name: DB_USER
value: devuser
- name: DB_PASSWORD
value: password
- name: SELENIUM_HOST
value: selenium-custom
- name: SELENIUM_PORT
value: "5000"
- name: DB_PORT
value: "5432"
The django app pod was not able to connect to the database pod because the environment variable for DB_HOST was not reflecting the db pods actual ip. Kubernetes injects service environment variable for each service in the format <SERVICE NAME..>_SERVICE_HOST and so since my db service was named dev_db_service, kubernetes automatically injected an environment variable DEV_DB_SERVICE_SERVICE_HOST into my django-app deployment. And so in my django app deployment manifest, the value of the environment variiable DB_HOST references the injected environment variable which had the db host ip address.
I also found out that I had to manually create the user for the database. In docker-compose simply setting the POSTGRES_USER and POSTGRES_PASSWORD created the db user but this did not work for me in microk8s. I had to access the pod via microk8s kubectl exec -it <db-pod-name..> -- bash and create the user manually. Once the db deployment and service manifests were correctly configured, I then applied the deployment for the django-app.
This is the deployment manifest for the db.
apiVersion: apps/v1
kind: Deployment
metadata:
name: dev-db
spec:
selector:
matchLabels:
app: dev-db
template:
metadata:
labels:
app: dev-db
spec:
containers:
- name: dev-db
image: postgres:13-alpine
ports:
- containerPort: 5432
name: postgres
volumeMounts:
- mountPath: "/var/lib/postgresql/data"
name: dev-db-data-storage
env:
- name: POSTGRES_DB
value: devdb
- name: POSTGRES_USER
value: devuser
- name: POSTGRES_PASSWORD
value: password
volumes:
- name: dev-db-data-storage
persistentVolumeClaim:
claimName: dev-db-persistent-volume-claim
This is the service manifest for the db..
apiVersion: v1
kind: Service
metadata:
name: dev-db-service
spec:
type: NodePort
selector:
app: dev-db
ports:
- name: "postgres"
protocol: TCP
port: 5432
targetPort: 5432
nodePort: 30432
Hope it helps someone facing the same issue..