I've been working with kubernetes for the past 6 months and we've deployed a few services.
We're just about to deploy another which stores encrypted data and puts the keys in KMS. This requires two service accounts, one for the data and one for the keys.
Data access to this must be audited. Since access to this data is very sensitive we are reluctant to put both service accounts in the name namespace as if compromised in any way the attacker could gain access to the data and the keys without it being audited.
For now we have one key in a secret and the other we're going to manually post to the single pod.
This is horrible as it requires that a single person be trusted with this key, and limits scalability. Luckily this service will be very low volume.
Has anyone else came up against the same problem? How have you gotten around it?
cheers
What you're describing is pretty common - using a key/ service account/ identity in Kubernetes secrets to access an external secret store.
I'm a bit confused by the double key concept - what are you gaining by having a key in both secrets and in the pod? If secrets are compromised, then etcd is compromised and you have bigger problems. I would suggest you focus instead on locking down secrets, using audit logs, and making the key is easy to rotate in case of compromise.
A few items to consider:
Data access to this must be audited
If you enable audit logging, every API call done via this service account will be logged. This may not help you if your service isn't ever called via the API, but considering you have a service account being used, it sounds like it would be.
For now we have one key in a secret and the other we're going to manually post to the single pod.
You might consider using Vault for this. If you store the secret in vault, you can use something like this to have the environment variable pushed down into the pod as an environment variable automatically. This is a little more involved than your process, but is considerably more secure.
You can also use Vault alongside Google Cloud KMS which is detailed in this article