207 lines
7.3 KiB
Plaintext
207 lines
7.3 KiB
Plaintext
---
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layout: docs
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page_title: Vault as the Server TLS Certificate Provider on Kubernetes
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description: >-
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Configuring the Consul Helm chart to use TLS certificates issued by Vault for the Consul server.
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---
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# Vault as the Server TLS Certificate Provider on Kubernetes
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## Overview
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To use Vault as the server TLS certificate provider on Kubernetes, complete a modified version of the steps outlined in the [Data Integration](/docs/k8s/deployment-configurations/vault/data-integration) section.
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Complete the following steps once:
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1. Create a Vault policy that authorizes the desired level of access to the secret.
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Repeat the following steps for each datacenter in the cluster:
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1. (Added) Configure allowed domains for PKI certificates
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1. Create Vault Kubernetes auth roles that link the policy to each Consul on Kubernetes service account that requires access.
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1. Update the Consul on Kubernetes helm chart.
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## Prerequisites
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Prior to setting up the data integration between Vault and Consul on Kubernetes, you will need to have:
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1. Read and completed the steps in the [Systems Integration](/docs/k8s/deployment-configurations/vault/systems-integration) section of [Vault as a Secrets Backend](/docs/k8s/deployment-configurations/vault).
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2. Read the [Data Integration Overview](/docs/k8s/deployment-configurations/vault/data-integration) section of [Vault as a Secrets Backend](/docs/k8s/deployment-configurations/vault).
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3. Complete the [Bootstrapping the PKI Engine](#bootstrapping-the-pki-engine) section.
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## Bootstrapping the PKI Engine
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Issue the following commands to enable and configure the PKI Secrets Engine to server
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TLS certificates to Consul.
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* Enable the PKI Secrets Engine:
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```shell-session
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$ vault secrets enable pki
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```
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* Tune the engine to enable longer TTL:
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```shell-session
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$ vault secrets tune -max-lease-ttl=87600h pki
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```
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* Generate the root CA:
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-> **Note:** The `common_name` value is comprised of combining `global.datacenter` dot `global.domain`.
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```shell-session
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$ vault write -field=certificate pki/root/generate/internal \
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common_name="dc1.consul" \
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ttl=87600h
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```
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## Create Vault policies
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To use Vault to issue Server TLS certificates, you will need to create the following:
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1. Create a policy that allows `["create", "update"]` access to the
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[certificate issuing URL](https://www.vaultproject.io/api-docs/secret/pki#generate-certificate) so the Consul servers can
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fetch a new certificate/key pair.
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The path to the secret referenced in the `path` resource is the same value that you will configure in the `server.serverCert.secretName` Helm configuration (refer to [Update Consul on Kubernetes Helm chart](#update-consul-on-kubernetes-helm-chart)).
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<CodeBlockConfig filename="consul-server-policy.hcl">
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```HCL
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path "pki/issue/consul-server" {
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capabilities = ["create", "update"]
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}
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```
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</CodeBlockConfig>
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1. Apply the Vault policy by issuing the `vault policy write` CLI command:
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```shell-session
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$ vault policy write consul-server consul-server-policy.hcl
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```
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1. Create a policy that allows `["read"]` access to the [CA URL](https://www.vaultproject.io/api-docs/secret/pki),
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this is required for the Consul components to communicate with the Consul servers in order to fetch their auto-encryption certificates.
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The path to the secret referenced in the `path` resource is the same value that you will configure in the `global.tls.caCert.secretName` Helm configuration (refer to [Update Consul on Kubernetes Helm chart](#update-consul-on-kubernetes-helm-chart)).
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<CodeBlockConfig filename="ca-policy.hcl">
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```HCL
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path "pki/cert/ca" {
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capabilities = ["read"]
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}
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```
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</CodeBlockConfig>
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```shell-session
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$ vault policy write ca-policy ca-policy.hcl
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```
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1. Configure allowed domains for PKI certificates.
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Next, a Vault role for the PKI engine will set the default certificate issuance parameters:
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```shell-session
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$ vault write pki/roles/consul-server \
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allowed_domains="<Allowed-domains-string>" \
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allow_subdomains=true \
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allow_bare_domains=true \
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allow_localhost=true \
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generate_lease=true \
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max_ttl="720h"
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```
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To generate the `<Allowed-domains-string>` use the following script as a template:
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```shell-session
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#!/bin/sh
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# NAME is set to either the value from `global.name` from your Consul K8s value file, or your $HELM_RELEASE_NAME-consul
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export NAME=consulk8s
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# NAMESPACE is where the Consul on Kubernetes is installed
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export NAMESPACE=consul
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# DATACENTER is the value of `global.datacenter` from your Helm values config file
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export DATACENTER=dc1
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echo allowed_domains=\"$DATACENTER.consul, $NAME-server, $NAME-server.$NAMESPACE, $NAME-server.$NAMESPACE.svc\"
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```
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1. Finally, Kubernetes auth roles need to be created for servers, clients, and components.
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Role for Consul servers:
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```shell-session
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$ vault write auth/kubernetes/role/consul-server \
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bound_service_account_names=<Consul server service account> \
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bound_service_account_namespaces=<Consul installation namespace> \
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policies=consul-server \
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ttl=1h
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```
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To find out the service account name of the Consul server,
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you can run:
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```shell-session
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$ helm template --release-name ${RELEASE_NAME} --show-only templates/server-serviceaccount.yaml hashicorp/consul -f values.yaml
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```
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Role for Consul clients:
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```shell-session
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$ vault write auth/kubernetes/role/consul-client \
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bound_service_account_names=<Consul client service account> \
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bound_service_account_namespaces=default \
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policies=ca-policy \
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ttl=1h
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```
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To find out the service account name of the Consul client, use the command below.
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```shell-session
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$ helm template --release-name ${RELEASE_NAME} --show-only templates/client-serviceaccount.yaml hashicorp/consul -f values.yaml
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```
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Role for CA components:
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```shell-session
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$ vault write auth/kubernetes/role/consul-ca \
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bound_service_account_names="*" \
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bound_service_account_namespaces=<Consul installation namespace> \
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policies=ca-policy \
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ttl=1h
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```
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The above Vault Roles will now be your Helm values for `global.secretsBackend.vault.consulServerRole` and
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`global.secretsBackend.vault.consulCARole` respectively.
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## Update Consul on Kubernetes Helm chart
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Next, configure the Consul Helm chart to
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use the server TLS certificates from Vault:
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<CodeBlockConfig filename="values.yaml">
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```yaml
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global:
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secretsBackend:
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vault:
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enabled: true
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consulServerRole: consul-server
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consulClientRole: consul-client
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consulCARole: consul-ca
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tls:
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enableAutoEncrypt: true
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enabled: true
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caCert:
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secretName: "pki/cert/ca"
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server:
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serverCert:
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secretName: "pki/issue/consul-server"
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extraVolumes:
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- type: "secret"
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name: <vaultCASecret>
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load: "false"
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```
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</CodeBlockConfig>
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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:
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```shell-session
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$ kubectl create secret generic vault-ca --from-file vault.ca=/path/to/your/vault/
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```
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