Service loses connection to Etcd DB when pod restarts - kubernetes

Question

I have a Go Lang REST service and ETCD DB in one container, deployed in kubernetes cluster using Deployment type. Whenever I try to restart the service pod, the service loses connectivity to ETCD, I have tried using stateful sets instead of deployment but still didn't help. My deployment looks something like below.
The ETCD fails restarting due to this issue: https://github.com/etcd-io/etcd/issues/10487
PVC :
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: XXXX
namespace: XXXX
annotations:
volume.beta.kubernetes.io/storage-class: glusterfs-storage
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 1Gi
Deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
name: XXX
namespace: XXX
spec:
replicas: X
XXXXXXX
template:
metadata:
labels:
app: rest-service
version: xx
spec:
hostAliases:
- ip: 127.0.0.1
hostnames:
- "etcd.xxxxx"
containers:
- name: rest-service
image: xxxx
imagePullPolicy: IfNotPresent
ports:
- containerPort: xxx
securityContext:
readOnlyRootFilesystem: false
capabilities:
add:
- IPC_LOCK
- name: etcd-db
image: quay.io/coreos/etcd:v3.3.11
imagePullPolicy: IfNotPresent
command:
- etcd
- --name=etcd-db
- --listen-client-urls=https://0.0.0.0:2379
- --advertise-client-urls=https://etcd.xxxx:2379
- --data-dir=/var/etcd/data
- --client-cert-auth
- --trusted-ca-file=xxx/ca.crt
- --cert-file=xxx/tls.crt
- --key-file=xxx/tls.key
volumeMounts:
- mountPath: /var/etcd/data
name: etcd-data
XXXX
ports:
- containerPort: 2379
volumes:
- name: etcd-data
persistentVolumeClaim:
claimName: XXXX
I would expect the DB to be able to connect to pod even when it restarts

Answer 1

Keeping application and database in one pod is one of the worst practices in Kubernetes. If you update application code - you have to restart pod to apply changes. So you restart database also just for nothing.
Solution is very simple - you should run application in one deployment and database - in another. That way you can update application without restarting database. In that case you can also scale app and DB separately, like add more replicas to app while keeping DB at 1 replicas or vice versa.