resolved this issue using git-sync sidecar container.

there is an extraContainers: option in values.yaml file. we can add kubernetes git-sync as a sidecar container to continuously sync from git.

extraContainers: 
  ## Additional containers to run alongside the Scheduler, Worker and Web pods
  ## This could, for example, be used to run a sidecar that syncs DAGs from object storage.
   - name: git-sync
     image: k8s.gcr.io/git-sync:v3.1.1
     volumeMounts:
      - name: ssh-key
        mountPath: /var/ssh
      - name: known-hosts
        mountPath: /var/knownhosts
      - name: git-sync-volume
        mountPath: /tmp/git

     env:
      - name: GIT_SYNC_REPO
        value: git@gitlab.example.com/test.git
      - name: GIT_SYNC_DEST
        value: git
      - name: GIT_SYNC_WAIT
        value: "10"
      - name: GIT_SYNC_SSH
        value: "true"
      - name: GIT_SSH_KEY_FILE
        value: /var/ssh/sshkey
      - name: GIT_SSH_KNOWN_HOSTS_FILE
        value: /var/knownhosts/known_hosts
  ## Additional volumeMounts to the main containers in the Scheduler, Worker and Web pods.
  extraVolumeMounts: 
     # - volumeMounts:
          - mountPath: "/var/ssh"
            name: ssh-key
            readOnly: true
          - mountPath: "/var/knownhosts"
            name: known-hosts
            readOnly: true
          - name: git-sync-volume
            mountPath: /tmp/git

  extraVolumes: 
     #- volumes:
        - name: ssh-key
          secret:
            secretName: dags-secret
            items:
            - key: key
              path: sshkey
        - name: known-hosts
          secret:
            secretName: dags-secret
            items:
            - key: known_hosts
              path: known_hosts

        - name: git-sync-volume
          emptyDir: {}