Kubernetes PVC with ReadWriteMany on AWS

Question

I want to setup a PVC on AWS, where I need ReadWriteMany as access mode. Unfortunately, EBS only supports ReadWriteOnce.

How could I solve this?

• I have seen that there is a beta provider for AWS EFS which supports ReadWriteMany, but as said, this is still beta, and its installation looks somewhat flaky.
• I could use node affinity to force all pods that rely on the EBS volume to a single node, and stay with ReadWriteOnce, but this limits scalability.

Are there any other ways of how to solve this? Basically, what I need is a way to store data in a persistent way to share it across pods that are independent of each other.

Answer 1

Using EFS without automatic provisioning

The EFS provisioner may be beta, but EFS itself is not. Since EFS volumes can be mounted via NFS, you can simply create a PersistentVolume with a NFS volume source manually -- assuming that automatic provisioning is not a hard requirement on your side:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-efs-volume
spec:
  capacity:
    storage: 100Gi # Doesn't really matter, as EFS does not enforce it anyway
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  mountOptions:
    - hard
    - nfsvers=4.1
    - rsize=1048576
    - wsize=1048576
    - timeo=600
    - retrans=2
  nfs:
    path: /
    server: fs-XXXXXXXX.efs.eu-central-1.amazonaws.com

You can then claim this volume using a PersistentVolumeClaim and use it in a Pod (or multiple Pods) as usual.

Alternative solutions

If automatic provisioning is a hard requirement for you, there are alternative solutions you might look at: There are several distributed filesystems that you can roll out on yourcluster that offer ReadWriteMany storage on top of Kubernetes and/or AWS. For example, you might take a look at Rook (which is basically a Kubernetes operator for Ceph). It's also officially still in a pre-release phase, but I've already worked with it a bit and it runs reasonably well. There's also the GlusterFS operator, which already seems to have a few stable releases.