open-consul/website/content/docs/k8s/installation/vault/connect-ca.mdx

---
layout: docs
page_title: Vault as the Service Mesh Certificate Provider on Kubernetes
description: >-
  Using Vault as the provider for the Service Mesh certificates on Kubernetes.
---

# Vault as the Service Mesh Certificate Provider on Kubernetes

-> **Note:** This feature requires Consul 1.11 or higher. As of v1.11,
Consul allows using Kubernetes auth methods to configure Connect CA.
This allows for automatic token rotation once the renewal is no longer possible.

In order to create Vault auth roles for the Consul servers for this feature, ensure that the Vault Kubernetes auth method is enabled as described in [Vault Kubernetes Auth Method](/docs/k8s/installation/vault#vault-kubernetes-auth-method).

To configure [Vault as the provider](/docs/connect/ca/vault) for the Consul service certificates,
you will first need to decide on the type of policy that is suitable for you.
To see the permissions that Consul would need in Vault, please see [Vault ACL policies](/docs/connect/ca/vault#vault-acl-policies)
documentation.

Once you have a policy, you will need to link that policy to the Consul server service account.

```shell-session
vault write auth/kubernetes/role/consul-server \
    bound_service_account_names=<Consul server service account> \
    bound_service_account_namespaces=<Consul installation namespace> \
    policies=<Connect CA policy> \
    ttl=1h
```

To find out the service account name of the Consul server,
you can run: 

```shell-session
helm template --release-name <your release name> -s templates/server-serviceaccount.yaml hashicorp/consul
```

Now we can configure the Consul Helm chart to use Vault as the Connect CA provider:

```yaml
global:
  secretsBackend:
    vault:
      enabled: true
      consulServerRole: consul-server
      consulClientRole: consul-client
      consulCARole: consul-ca
      connectCA:
        address: <the address of the Vault server>
        rootPKIPath: <the path to root PKI>
        intermediatePKIPath: <the path to intermediate PKI>
      ca:
        secretName: <vaultCASecret>
```

The `address` you provide to the `connectCA` configuration can be a Kubernetes DNS
address if the Vault cluster is running the same Kubernetes cluster.
The `rootPKIPath` and `intermediatePKIPath` should be the same as the ones
defined in your Connect CA policy. Behind the scenes, Consul will authenticate to Vault using a Kubernetes
service account using the [Kubernetes auth method](https://www.vaultproject.io/docs/auth/kubernetes) and will use the Vault token for any API calls to Vault. If the Vault token can not be renewed, Consul will re-authenticate to
generate a new Vault token. 

The `vaultCASecret` is the Kubernetes secret that stores the CA Certificate that is used for Vault communication. To provide a CA, you first need to create a Kubernetes secret containing the CA. For example, you may create a secret with the Vault CA like so:

```
kubectl create secret generic vault-ca --from-file vault.ca=/path/to/your/vault/ca
```

### Secondary Datacenters

To configure Vault as the Connect CA in secondary datacenters, you need to make sure that the Root CA path is the same,
but the intermediate is different for each datacenter. In the `connectCA` Helm configuration for a secondary datacenter,
you can specify a `intermediatePKIPath` that is, for example, prefixed with the datacenter
for which this configuration is intended (e.g. `dc2/connect-intermediate`).