Consul Secrets Engine

The Consul secrets engine generates Consul API tokens dynamically based on Consul ACL policies.

Setup

Most secrets engines must be configured in advance before they can perform their functions. These steps are usually completed by an operator or configuration management tool.

Enable the Consul secrets engine:
```
$ vault secrets enable consul
Success! Enabled the consul secrets engine at: consul/
```
By default, the secrets engine will mount at the name of the engine. To enable the secrets engine at a different path, use the -path argument.

Bootstrap the Consul ACL system if not already done. To begin configuring the secrets engine, we must give Vault the necessary credentials to manage Consul.

In Consul versions below 1.4, acquire a management token from Consul using the acl_master_token from your Consul configuration file, or another management token:

$ curl \
    --header "X-Consul-Token: my-management-token" \
    --request POST \
    --data '{"Name": "sample", "Type": "management"}' \
    https://consul.rocks/v1/acl/create

Vault must have a "management" type token so that it can create and revoke ACL tokens. The response will return a new token:

{
  "ID": "7652ba4c-0f6e-8e75-5724-5e083d72cfe4"
}

For Consul 1.4 and above, use the command line to generate a token with the appropriate policy:

$ CONSUL_HTTP_TOKEN="<management-token>" consul acl token create -policy-name="global-management"
AccessorID:   865dc5e9-e585-3180-7b49-4ddc0fc45135
SecretID:     ef35f0f1-885b-0cab-573c-7c91b65a7a7e
Description:
Local:        false
Create Time:  2018-10-22 17:40:24.128188 -0700 PDT
Policies:
    00000000-0000-0000-0000-000000000001 - global-management

Configure Vault to connect and authenticate to Consul:

$ vault write consul/config/access \
    address="127.0.0.1:8500" \
    token="7652ba4c-0f6e-8e75-5724-5e083d72cfe4"
Success! Data written to: consul/config/access

Configure a role that maps a name in Vault to a Consul ACL policy. Depending on your Consul version, you will either provide a policy document and a token_type, or a set of policies. When users generate credentials, they are generated against this role.
For Consul versions below 1.4, the policy must be base64-encoded. The policy language is documented by Consul.
Write a policy and proceed to link it to the role:
```
$ vault write consul/roles/my-role policy="$(base64 <<< 'key "" { policy = "read" }')"
Success! Data written to: consul/roles/my-role
```
For Consul versions 1.4 and above, generate a policy in Consul, and proceed to link it to the role:
```
$ vault write consul/roles/my-role policies="readonly"
Success! Data written to: consul/roles/my-role
```
For Consul versions 1.5 and above, generate a role in Consul, and proceed to link it to the role:
```
$ vault write consul/roles/my-role consul_roles="api-server"
Success! Data written to: consul/roles/my-role
```
Token lease duration: If you do not specify a value for ttl (or lease for Consul versions below 1.4) the tokens created using Vault's Consul secrets engine are created with a Time To Live (TTL) of 30 days. You can change the lease duration by passing -ttl=<duration> to the command above with "duration" being a string with a time suffix like "30s" or "1h".
For Enterprise users, you may further limit a role's access by adding the optional parameters consul_namespace and/or partition. Please refer to Consul's namespace documentation and admin partition documentation for further information about these features.
For Consul versions 1.7 and above, link a Consul namespace to the role:
```
$ vault write consul/roles/my-role consul_roles="namespace-management" consul_namespace="ns1"
Success! Data written to: consul/roles/my-role
```
For Consul version 1.11 and above, link an admin partition to a role:
```
$ vault write consul/roles/my-role consul_roles="admin-management" partition="admin1"
Success! Data written to: consul/roles/my-role
```

Usage

After the secrets engine is configured and a user/machine has a Vault token with the proper permission, it can generate credentials.

Generate a new credential by reading from the /creds endpoint with the name of the role:

$ vault read consul/creds/my-role
Key                 Value
---                 -----
lease_id            consul/creds/my-role/b2469121-f55f-53c5-89af-a3ba52b1d6d8
lease_duration      768h
lease_renewable     true
accessor            c81b9cf7-2c4f-afc7-1449-4e442b831f65
consul_namespace    ns1
local               false
partition           admin1
token               642783bf-1540-526f-d4de-fe1ac1aed6f0

Expired token rotation: Once a token's TTL expires, then Consul operations will no longer be allowed with it. This requires you to have an external process to rotate tokens. At this time, the recommended approach for operators is to rotate the tokens manually by creating a new token using the vault read consul/creds/my-role command. Once the token is synchronized with Consul, apply the token to the agents using the Consul API or CLI.

tutorials

Refer to Administer Consul Access Control Tokens with Vault for a step-by-step tutorial.

API

The Consul secrets engine has a full HTTP API. Please see the Consul secrets engine API for more details.