Some of these date back to older versions but efforts are made to keep the most important - sometimes :)

LambdaStack Kubernetes with Hashicorp Vault integration

Affected version: 0.7.x

1. Introduction

We want to provide integration of Kubernetes with Hashicorp Vault with couple of different modes:

1. vault - prod/dev mode without https
2. vault - prod/dev mode with https
3. vault - cluster with raft storage

We are not providing vault in vault development mode as this doesn't provide data persitency.

If user would like then can use automatic injecting of secrets into Kubernetes pods with usage of sidecar integration provided by Hashicorp Vault agent. Sidecar will based on annotations for pods inject secrets as files to annotated pods.

2. Goal

In LambdaStack you can use Kubernetes secrets stored in etcd. We want to provide integration with Hashicorp Vault to provide additional security for secrets used inside applications running in LambdaStack and also provide possibilty of usage safely secrets for components that are running outside of Kubernetes cluster.

3. Design proposals

In all deployment models vault is installed outside Kubernetes cluster as a separate service. There is a possibility of usage Hashicorp Vault deployed on Kubernetes cluster but this scenario is not covered in this document.

Integration between Kubernetes and Hashicorp Vault can be achieved via Hashicorp Vault Agent that is deployed on Kubernetes cluster using Helm. Also to provide this Hashicorp Vault needs to be configured with proper policies and enabling kubernetes method of authentication.

In every mode we want to provide possibility to perform automatic unseal via script, but this solution is better suited for development scenario. In production however to maximize security level unseal should be performed manually.

In all scenarios machine on which Hashicorp Vault will be running swap will be disabled and Hashicorp Vault will run under user with limited privileges (e.g. vault). User under which Hashicorp Vault will be running will have ability to use the mlock syscall In configuration from LambdaStack side we want to provide possibility to turn off dumps at the system level (turned off by default), use auditing (turned on by default), expose UI (by default set to disabled) and disable root token after configuration (by default root token will be disabled after deployment).

We want to provide three scenarios of installing Hashicorp Vault:

1. vault - prod/dev mode without https
2. vault - prod/dev mode with https
3. vault - cluster with raft storage

1. vault - prod/dev mode without https

In this scenario we want to use file storage for secrets. Vault can be set to manual or automatic unseal with script. In automatic unseal mode file with unseal keys is stored in file in safe location with permission to read only by vault user. In case of manual unseal vault post-deployment configuration script needs to be executed against vault. Vault is installed as a service managed by systemd. Traffic in this scenario is served via http, which make possible to perform man in the middle attacks, so this option should be only used in development scenarios.

2. vault - prod/dev mode with https

This scenario differs from previous with usage of https. In this scenario we should cover also generation of keys with usage of PKI, to provide certificate and mutual trust between the endpoints.

3. vault - cluster with raft storage

In this scenario we want to use raft storage for secrets. Raft storage is used for cluster setup and doesn't require additional Consul component what makes configuration easier and requires less maintenance. It also limit network traffic and increase performance. In this scenario we can also implement auto-unseal provided with Transient Secrets from Hashicorp Vault.

In this scenario at least 3 nodes are required, but preferable is 5 nodes setup to provide quorum for raft protocol. This can cover http and also https traffic.

4. Further extensions

We can provide additional components for vault unsealing - like integration with pgp keys to encrypt services and auto-unsealing with Transient Secrets from Hashicorp Vault. We can also add integration with Prometheus to share statistics with it.