370 lines
15 KiB
Plaintext
370 lines
15 KiB
Plaintext
---
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layout: docs
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page_title: Service Mesh Certificate Authority - Vault
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description: >-
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You can use a Vault PKI secrets engine as the Consul service mesh's certificate authority to secure your service mesh. Learn how to configure the Vault CA as a root CA or an intermediate CA connected to an existing PKI system, and how to manage PKI paths with either Vault or Consul.
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---
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# Vault as a Service Mesh Certificate Authority
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You can configure Consul to use [Vault](https://www.vaultproject.io/) as the certificate authority (CA) so that Vault can manage and sign certificates distributed to services in the mesh.
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The Vault CA provider uses the [Vault PKI secrets engine](/vault/docs/secrets/pki) to generate and sign certificates.
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This page describes how configure the Vault CA provider.
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> **Tutorial:** Complete the [Vault as Consul Service Mesh Certification Authority](/consul/tutorials/vault-secure/vault-pki-consul-connect-ca) tutorial for hands-on guidance on how to configure Vault as the Consul service mesh certification authority.
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## Requirements
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- Refer to [Service Mesh Certificate Authority Overview](/consul/docs/connect/ca) for important background information about how Consul manages certificates with configurable CA providers.
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- Vault 0.10.3 to 1.10.x.
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~> **Compatibility note:** If you use Vault 1.11.0+ as Consul's Connect CA, versions of Consul released before Dec 13, 2022 will develop an issue with Consul control plane or service mesh communication ([GH-15525](https://github.com/hashicorp/consul/pull/15525)). Use or upgrade to a [Consul version that includes the fix](https://support.hashicorp.com/hc/en-us/articles/11308460105491#01GMC24E6PPGXMRX8DMT4HZYTW) to avoid this problem.
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## Enable Vault as the CA
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You can enable Vault as the CA by configuring Consul to use `"vault"` as the CA provider
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and including the required provider configuration options.
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You can provide the CA configuration in the server agents' configuration file
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or in the body of a `PUT` request to the
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[`/connect/ca/configuration`](/consul/api-docs/connect/ca#update-ca-configuration) API endpoint.
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Refer to the [Configuration Reference](#configuration-reference) for details about configuration options and for example use cases.
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The following example shows the required configurations for a default implementation:
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<CodeTabs heading="Connect CA configuration" tabs={["Agent configuration", "API"]}>
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<CodeBlockConfig filename="/etc/consul.d/config.hcl" highlight="4,6-9">
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```hcl
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# ...
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connect {
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enabled = true
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ca_provider = "vault"
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ca_config {
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address = "http://localhost:8200"
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token = "<vault-token-with-necessary-policy>"
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root_pki_path = "connect-root"
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intermediate_pki_path = "connect-dc1-intermediate"
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}
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}
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```
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</CodeBlockConfig>
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<CodeBlockConfig highlight="2,4-7">
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```json
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{
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"Provider": "vault",
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"Config": {
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"Address": "http://localhost:8200",
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"Token": "<vault-token-with-necessary-policy>",
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"RootPKIPath": "connect-root",
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"IntermediatePKIPath": "connect-dc1-intermediate"
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}
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}
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```
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</CodeBlockConfig>
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</CodeTabs>
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## Configuration Reference
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You can specify the following configuration options.
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Note that a configuration option's name may differ between API calls and the agent configuration file.
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The first key refers to the option name for use in API calls.
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The key after the slash refers to the corresponding option name in the agent configuration file.
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- `Address` / `address` (`string: <required>`) - The address of the Vault
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server.
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- `Token` / `token` (`string: ""`) - A token for accessing Vault.
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This is write-only and will not be exposed when reading the CA configuration.
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This token must have [proper privileges](#vault-acl-policies) for the PKI
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paths configured. In Consul 1.8.5 and later, if the token has the [renewable](/vault/api-docs/auth/token#renewable)
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flag set, Consul will attempt to renew its lease periodically after half the
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duration has expired.
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!> **Warning:** You must either provide a token or configure an auth method below.
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- `AuthMethod` / `auth_method` (`map: nil`) - Vault auth method to use for logging in to Vault.
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Please see [Vault Auth Methods](/vault/docs/auth) for more information
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on how to configure individual auth methods. If auth method is provided, Consul will obtain
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a new token from Vault when the token can no longer be renewed.
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- `Type`/ `type` (`string: ""`) - The type of Vault auth method.
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- `MountPath`/ `mount_path` (`string: <AuthMethod.Type>`) - The mount path of the auth method.
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If not provided the auth method type will be used as the mount path.
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- `Params`/`params` (`map: nil`) - The parameters to configure the auth method. Please see
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[Vault Auth Methods](/vault/docs/auth) for information on how to configure the
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auth method you wish to use. If using the Kubernetes auth method,
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Consul will read the service account token from the
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default mount path `/var/run/secrets/kubernetes.io/serviceaccount/token` if the `jwt` parameter
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is not provided.
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- `RootPKIPath` / `root_pki_path` (`string: <required>`) - The path to
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a PKI secrets engine for the root certificate.
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If the path does not
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exist, Consul will mount a new PKI secrets engine at the specified path with the
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`RootCertTTL` value as the root certificate's TTL. If the `RootCertTTL` is not set,
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a [`max_lease_ttl`](/vault/api-docs/system/mounts)
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of 87600 hours, or 10 years is applied by default as of Consul 1.11 and later. Prior to Consul 1.11,
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the root certificate TTL was set to 8760 hour, or 1 year, and was not configurable.
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The root certificate will expire at the end of the specified period.
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When WAN Federation is enabled, each secondary datacenter must use the same Vault cluster and share the same `root_pki_path`
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with the primary datacenter.
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To use an intermediate certificate as the primary CA in Consul, initialize the
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`RootPKIPath` in Vault with a PEM bundle. The first certificate in the bundle
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must be the intermediate certificate that Consul will use as the primary CA.
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The last certificate in the bundle must be a root certificate. The bundle
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must contain a valid chain, where each certificate is followed by the certificate
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that authorized it.
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- `RootPKINamespace` / `root_pki_namespace` (`string: <optional>`) - The absolute namespace
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that the `RootPKIPath` is in. Setting this parameter overrides the `Namespace` option for the `RootPKIPath`. Introduced in 1.12.3.
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- `IntermediatePKIPath` / `intermediate_pki_path` (`string: <required>`) -
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The path to a PKI secrets engine for the generated intermediate certificate.
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This certificate will be signed by the configured root PKI path. If this
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path does not exist, Consul will attempt to mount and configure this
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automatically.
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When WAN Federation is enabled, every secondary
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datacenter must specify a unique `intermediate_pki_path`.
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- `IntermediatePKINamespace` / `intermediate_pki_namespace` (`string: <optional>`) - The absolute namespace
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that the `IntermediatePKIPath` is in. Setting this parameter overrides the `Namespace` option for the `IntermediatePKIPath`. Introduced in 1.12.3.
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- `CAFile` / `ca_file` (`string: ""`) - Specifies an optional path to the CA
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certificate used for Vault communication. If unspecified, this will fallback
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to the default system CA bundle, which varies by OS and version.
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- `CAPath` / `ca_path` (`string: ""`) - Specifies an optional path to a folder
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containing CA certificates to be used for Vault communication. If
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unspecified, this will fallback to the default system CA bundle, which
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varies by OS and version.
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- `CertFile` / `cert_file` (`string: ""`) - Specifies the path to the
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certificate used for Vault communication. If this is set, then you also need to
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set `key_file`.
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- `KeyFile` / `key_file` (`string: ""`) - Specifies the path to the private
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key used for Vault communication. If this is set, then you also need to set
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`cert_file`.
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- `TLSServerName` / `tls_server_name` (`string: ""`) - Specifies an optional
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string used to set the SNI host when connecting to Vault via TLS.
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- `TLSSkipVerify` / `tls_skip_verify` (`bool: false`) - Specifies if SSL peer
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validation should be enforced.
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- `Namespace` / `namespace` (`string: <optional>`) - The Vault Namespace that
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the `Token` and PKI Certificates are a part of. Vault Namespaces are a Vault
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Enterprise feature. Added in Consul 1.11.0
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@include 'http_api_connect_ca_common_options.mdx'
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### Root and Intermediate PKI Paths
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The Vault CA provider uses two separately configured
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[PKI secrets engines](/vault/docs/secrets/pki)
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for managing Consul service mesh certificates.
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The `RootPKIPath` is the PKI engine for the root certificate.
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Consul uses this root certificate to sign the intermediate certificate.
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Consul does not attempt to write or modify any data within the root PKI path.
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The `IntermediatePKIPath` is the PKI engine used for storing the intermediate
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signed with the root certificate. The intermediate signs all leaf
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certificates, and Consul may periodically generate new intermediates for
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automatic rotation. Therefore, Consul requires write access to this path.
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For each path, if the path does not exist, Consul attempts to mount and initialize
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a PKI secrets engine at that path. For this operation to succeed,
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the provided [Vault token](#token) must have the [required Vault privileges](#vault-acl-policies).
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If the path does already exist, Consul uses the PKI secrets engine at that path as configured.
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### Configure Vault ACL policies ((#vault-acl-policies))
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The Vault CA provider requires a [Vault token](#token) with a specific set of Vault privileges
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depending on whether you would prefer to control mount configuration from Vault or to delegate
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that responsibility to Consul.
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Use [Vault-managed PKI paths](#vault-managed-pki-paths) to obtain the following benefits:
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- Enables use of a root CA external to Consul by instantiating the PKI secrets engine at
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[`RootPKIPath`](#rootpkipath) with an intermediate certificate
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- Retain full control over PKI mount creation, and over `RootPKIPath` mount configuration
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Otherwise, use [Consul-managed PKI paths](#consul-managed-pki-paths) to let Consul fully automate PKI management.
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The following sections describe the Vault policy needed for both options.
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The policy snippets use placeholder values for `RootPKIPath` and `IntermediatePKIPath`.
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Replace them to match the path values in your CA provider configuration.
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#### Define a policy for Vault-managed PKI paths ((#vault-managed-pki-paths))
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To use Vault-managed PKI paths, you must first instantiate and configure PKI secrets engines at
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`RootPKIPath` and `IntermediatePKIPath`.
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Then, attach the following Vault ACL policy to the CA provider's
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[Vault token](#token) or [auth method](#authmethod):
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1. Allow Consul to read both PKI mounts and to manage the intermediate PKI mount configuration:
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<CodeBlockConfig filename="vault-managed-pki-policy.hcl">
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```hcl
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path "/sys/mounts/<root_pki_path>" {
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capabilities = [ "read" ]
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}
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path "/sys/mounts/<intermediate_pki_path>" {
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capabilities = [ "read" ]
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}
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path "/sys/mounts/<intermediate_pki_path>/tune" {
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capabilities = [ "update" ]
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}
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```
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</CodeBlockConfig>
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1. Allow Consul read-only access to the root PKI engine, to automatically rotate
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intermediate CAs as needed, and full use of the intermediate PKI engine:
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<CodeBlockConfig filename="vault-managed-pki-policy.hcl">
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```hcl
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path "/<root_pki_path>/" {
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capabilities = [ "read" ]
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}
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path "/<root_pki_path>/root/sign-intermediate" {
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capabilities = [ "update" ]
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}
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path "/<intermediate_pki_path>/*" {
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capabilities = [ "create", "read", "update", "delete", "list" ]
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}
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```
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</CodeBlockConfig>
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1. Allow Consul to renew its Vault token if the token is renewable.
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The rule enables the token to be renewed whether it is provided
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[directly](#token) in the CA provider configuration or presented in an [auth method](#authmethod).
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<CodeBlockConfig filename="vault-managed-pki-policy.hcl">
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```hcl
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path "auth/token/renew-self" {
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capabilities = [ "update" ]
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}
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path "auth/token/lookup-self" {
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capabilities = [ "read" ]
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}
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```
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</CodeBlockConfig>
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#### Define a policy for Consul-managed PKI paths ((#consul-managed-pki-paths))
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To use Consul-managed PKI paths, ensure no PKI secrets engines are mounted at
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`RootPKIPath` and `IntermediatePKIPath`.
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Then, attach the following Vault ACL policy to the CA provider's
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[Vault token](#token) or [auth method](#authmethod):
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1. Allow Consul to create and manage both PKI engines:
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<CodeBlockConfig filename="consul-managed-pki-policy.hcl">
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```hcl
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path "/sys/mounts/<root_pki_path>" {
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capabilities = [ "create", "read", "update", "delete", "list" ]
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}
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path "/sys/mounts/<intermediate_pki_path>" {
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capabilities = [ "create", "read", "update", "delete", "list" ]
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}
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path "/sys/mounts/<intermediate_pki_path>/tune" {
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capabilities = [ "update" ]
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}
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```
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</CodeBlockConfig>
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1. Allow Consul full use of both PKI engines:
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<CodeBlockConfig filename="consul-managed-pki-policy.hcl">
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```hcl
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path "/<root_pki_path>/*" {
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capabilities = [ "create", "read", "update", "delete", "list" ]
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}
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path "/<intermediate_pki_path>/*" {
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capabilities = [ "create", "read", "update", "delete", "list" ]
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}
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```
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</CodeBlockConfig>
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1. Allow Consul to renew its Vault token if the token is renewable.
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The rule enables the token to be renewed whether it is provided
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[directly](#token) in the CA provider configuration or presented in an [auth method](#authmethod).
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<CodeBlockConfig filename="consul-managed-pki-policy.hcl">
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```hcl
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path "auth/token/renew-self" {
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capabilities = [ "update" ]
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}
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path "auth/token/lookup-self" {
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capabilities = [ "read" ]
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}
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```
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</CodeBlockConfig>
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#### Additional Vault ACL policies for sensitive operations
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Additional Vault permissions are required while you perform the
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following CA provider configuration changes:
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- Changing the provider from Vault to a different provider, such as Consul's built-in provider
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- Changing the `RootPKIPath`
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Those configuration modifications trigger a root CA change that requires an
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extremely privileged root cross-sign operation.
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For that operation to succeed, the CA provider's [Vault token](#token) or
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[auth method](#authmethod) must contain the following rule:
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<CodeBlockConfig filename="temporary-sensitive-operation-pki-policy.hcl">
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```hcl
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path "<root_pki_path>/root/sign-self-issued" {
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capabilities = [ "sudo", "update" ]
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}
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```
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</CodeBlockConfig>
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We recommend using the following process when performing such a CA provider
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configuration change to minimize the time that a privileged Vault token is in use:
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1. Create a new Vault token that includes both the `root/sign-self-issued`
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permission and the standard permissions for the current Consul or Vault
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managed PKI paths.
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1. Modify the CA provider configuration to use that new Vault token.
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1. Perform the CA provider configuration change that triggers the extremely privileged
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root cross-sign operation. If the configuration change maintains Vault
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as the provider but modifies `RootPKIPath`, the configuration change must
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include a Vault token or auth method with standard permissions for the new
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Consul or Vault managed PKI paths.
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