Storing the ACL Bootstrap Token in Vault

This topic describes how to configure the Consul Helm chart to use an ACL bootstrap token stored in Vault.

Overview

To use an ACL bootstrap token stored in Vault, follow the steps outlined in the Data Integration section.

Complete the following steps once:

1. Store the secret in Vault.
2. Create a Vault policy that authorizes the desired level of access to the secret.

Repeat the following steps for each datacenter in the cluster:

1. Create Vault Kubernetes auth roles that link the policy to each Consul on Kubernetes service account that requires access.
2. Update the Consul on Kubernetes helm chart.

Prerequisites

Prior to setting up the data integration between Vault and Consul on Kubernetes, you will need to have:

1. Read and completed the steps in the Systems Integration section of Vault as a Secrets Backend.
2. Read the Data Integration Overview section of Vault as a Secrets Backend.

Store the Secret in Vault

First, generate and store the ACL bootstrap token in Vault. You will only need to perform this action once:

$ vault kv put consul-kv/secret/bootstrap-token token="$(uuidgen | tr '[:upper:]' '[:lower:]')"

Create Vault policy

Next, you will need to create a Vault policy that allows read access to this secret.

The path to the secret referenced in the path resource is the same value that you will configure in the global.acls.bootstrapToken.secretName Helm configuration (refer to Update Consul on Kubernetes Helm chart).

path "consul-kv/data/secret/bootstrap-token" {
  capabilities = ["read"]
}

Apply the Vault policy by issuing the vault policy write CLI command:

$ vault policy write bootstrap-token-policy bootstrap-token-policy.hcl

Create Vault Authorization Roles for Consul

Next, you will create Kubernetes auth roles for the Consul server-acl-init container that runs as part of the Consul server statefulset:

$ vault write auth/kubernetes/role/consul-server-acl-init \
    bound_service_account_names=<Consul server service account> \
    bound_service_account_namespaces=<Consul installation namespace> \
    policies=bootstrap-token-policy \
    ttl=1h

To find out the service account name of the Consul server-acl-init job (i.e. the Consul server service account name), you can run the following helm template command with your Consul on Kubernetes values file:

$ helm template --release-name ${RELEASE_NAME} -s templates/server-acl-init-serviceaccount.yaml hashicorp/consul -f values.yaml

Update Consul on Kubernetes Helm chart

Now that you have configured Vault, you can configure the Consul Helm chart to use the ACL bootstrap token in Vault:

global:
  secretsBackend:
    vault:
      enabled: true
      manageSystemACLsRole: consul-server-acl-init
  acls:
    bootstrapToken:
      secretName: consul-kv/data/secret/bootstrap-token
      secretKey: token

Note that global.acls.bootstrapToken.secretName is the path of the secret in Vault. This should be the same path as the one you included in your Vault policy. global.acls.bootstrapToken.secretKey is the key inside the secret data. This should be the same as the key you passed when creating the ACL replication token secret in Vault.