k8s-deployment-shared-volume.yml

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      initContainers:
        - name: certs
          ...
          volumeMounts:
            - mountPath: /vault
              name: vault-tls
      containers:
        - name: myapp
          ...
          volumeMounts:
            - name: vault-tls
              mountPath: /vault
              readOnly: true
      volumes:
        - name: vault-tls
          emptyDir: {}