I'm running atmoz/sftp deployment for sftp on GKE. I succeeded mounting a persistent volume and using a configmap to mount public keys for users, but I can't mount a host key so every time my container is restarting I'm getting a warning that my host key has changed..

I tried to mount it to /etc/ssh and changing sshd_config and nothing worked - it says file already exists, overwrite? (y/n) and I can't manipulate it because it's inside the container.

And even if I try to run a command, any command like echo, the container is turning into CrashLoopBackhOff

my configmap:

apiVersion: v1
data:
  ssh_host_rsa_key: |
    <my key>
kind: ConfigMap
metadata:
  name: ssh-host-rsa
  namespace: default

my deployment yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
  name: sftp
  namespace: default
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: sftp
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: sftp
    spec:
      containers:
      - args:
        - client::::sftp
        env:
        - name: sftp
          value: "1"
        image: atmoz/sftp
        imagePullPolicy: IfNotPresent
        name: sftp
        ports:
        - containerPort: 22
          name: sftp
          protocol: TCP
        resources: {}
        securityContext:
          capabilities:
            add:
            - SYS_ADMIN
          procMount: Default
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /home/client/sftp
          name: sftp
        - mountPath: /home/client/.ssh/keys
          name: sftp-public-keys
        - mountPath: /etc/ssh
          name: ssh-host-ed25519
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext:
        fsGroup: 100
      terminationGracePeriodSeconds: 30
      volumes:
      - name: sftp
        persistentVolumeClaim:
          claimName: sftp-uat
      - configMap:
          defaultMode: 420
          name: sftp-public-keys
        name: sftp-public-keys
      - configMap:
          defaultMode: 420
          name: ssh-host-ed25519
        name: ssh-host-ed25519

the echo test:

containers:
          - args:
            - client::::sftp
            env:
            - name: sftp
              value: "1"
            image: atmoz/sftp
            command:
            - "echo hi"
            imagePullPolicy: IfNotPresent
            name: sftp
            ports:
            - containerPort: 22
              name: sftp
              protocol: TCP
            resources: {}
            securityContext:
              capabilities:
                add:
                - SYS_ADMIN
              procMount: Default
            terminationMessagePath: /dev/termination-log
            terminationMessagePolicy: File
            volumeMounts:
            - mountPath: /home/client/sftp
              name: sftp
            - mountPath: /home/client/.ssh/keys
              name: sftp-public-keys
            - mountPath: /etc/ssh
              name: ssh-host-ed25519

Any ideas?