Kubernetes - Pod which encapsulates DB is crashing - kubernetes

Question

I am experiencing issues when I try to deploy my Django application to Kubernetes cluster. More specifically, when I try to deploy PostgreSQL.
Here is what my .YML deployment file looks like:
apiVersion: v1
kind: Service
metadata:
name: postgres-service
spec:
selector:
app: postgres-container
tier: backend
ports:
- protocol: TCP
port: 5432
targetPort: 5432
type: ClusterIP
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: postgres-pv
labels:
type: local
spec:
accessModes:
- ReadWriteOnce
capacity:
storage: 2Gi
hostPath:
path: /tmp/data/persistent-volume-1 #U okviru cvora n
persistentVolumeReclaimPolicy: Retain
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: postgres-pv-claim
labels:
type: local
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 2Gi
---
apiVersion: apps/v1beta2
kind: Deployment
metadata:
name: postgres
spec:
replicas: 1
selector:
matchLabels:
app: postgres-container
tier: backend
template:
metadata:
labels:
app: postgres-container
tier: backend
spec:
containers:
- name: postgres-container
image: postgres:9.6.6
env:
- name: POSTGRES_USER
valueFrom:
secretKeyRef:
name: postgres-credentials
key: user
- name: POSTGRES_PASSWORD
valueFrom:
secretKeyRef:
name: postgres-credentials
key: password
- name: POSTGRES_DB
value: agent_technologies_db
ports:
- containerPort: 5432
volumeMounts:
- name: postgres-volume-mount
mountPath: /var/lib/postgresql/data/db-files
volumes:
- name: postgres-volume-mount
persistentVolumeClaim:
claimName: postgres-pv-claim
- name: postgres-credentials
secret:
secretName: postgres-credentials
Here is what I get when I run kubectl get pods command :
NAME READY STATUS RESTARTS AGE
agent-technologies-deployment-7c7c6676ff-8p49r 1/1 Running 0 2m
agent-technologies-deployment-7c7c6676ff-dht5h 1/1 Running 0 2m
agent-technologies-deployment-7c7c6676ff-gn8lp 1/1 Running 0 2m
agent-technologies-deployment-7c7c6676ff-n9qql 1/1 Running 0 2m
postgres-8676b745bf-8f7jv 0/1 CrashLoopBackOff 4 3m
And here is what I get when I try to inspect what is going on with PostgreSQL deployment by using kubectl logs $pod_name:
initdb: directory "/var/lib/postgresql/data" exists but is not empty
If you want to create a new database system, either remove or empty
the directory "/var/lib/postgresql/data" or run initdb
with an argument other than "/var/lib/postgresql/data".
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.
The database cluster will be initialized with locale "en_US.utf8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".
Data page checksums are disabled.
Note: I am using Google Cloud as a provider.

Answer 1

You can't have your db in /var/lib/postgres/data/whatever.
Change that path by /var/lib/postgres/whatever and it will work.
17.2.1. Use of Secondary File Systems
Many installations create their database clusters on file systems (volumes) other than the machine's "root" volume. If you choose to do this, it is not advisable to try to use the secondary volume's topmost directory (mount point) as the data directory. Best practice is to create a directory within the mount-point directory that is owned by the PostgreSQL user, and then create the data directory within that. This avoids permissions problems, particularly for operations such as pg_upgrade, and it also ensures clean failures if the secondary volume is taken offline.
And, by the way, I had to create a secret, as it is not in the post:
apiVersion: v1
kind: Secret
metadata:
name: postgres-credentials
type: Opaque
data:
user: cG9zdGdyZXM= #postgres
password: cGFzc3dvcmQ= #password
Note that the username needs to be "postgres". I don't know if you are covering this...

Answer 2

Adding to what #suren answered.
I had this issue while running postgresql-setup --initdb in RHEL 8.4. I was getting this error :
Initializing database in '/var/lib/pgsql/data'
ERROR: Initializing database failed, possibly see /var/lib/pgsql/initdb_postgresql.log
So, following suren's suggestion, I deleted the 'data' folder and ran the command again. Worked like a charm!