HCP Terraform secrets engine

The HCP Terraform secrets engine for Vault generates HCP Terraform API tokens dynamically for Organizations, Teams, and Users.

This page will show a quick start for this backend. For detailed documentation on every path, use vault path-help after mounting the backend.

Quick start

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.

1. Enable the HCP Terraform secrets engine:

   $ vault secrets enable terraform
   Success! Enabled the terraform secrets engine at: terraform/
   

   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.

2. Configure Vault to connect and authenticate to HCP Terraform:

   $ vault write terraform/config \
       token=Vhz7652ba4c-0f6e-8e75-5724-5e083d72cfe4
   Success! Data written to: terraform/config
   

   See HCP Terraform's documentation on API tokens to determine the appropriate API token for use with the secret engine. In order to perform all operations, a User API token is recommended.

3. Configure a role that maps a name in Vault to a HCP Terraform user. At this time the HCP Terraform API does not allow dynamic user generation. As a result this secret engine creates dynamic API tokens for an existing user, and manages the lifecycle of that API token. You will need to know the User ID in order to generate User API tokens for that user. You can use the HCP Terraform Account API to find the desired User ID.

   $ vault write terraform/role/my-role user_id=user-12345abcde
   Success! Data written to: terraform/role/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 terraform/creds/my-role
Key                Value
---                -----
lease_id           terraform/creds/my-user/A_LEASE_ID_PdvmJjACTtKrY2I
lease_duration     180s
lease_renewable    true
token              TJFDSIFDSKFEKZX.FKFKA.akjlfdiouajlkdakadfiowe
token_id           at-123acbdfask

Organization, team, and user roles

HCP Terraform supports three distinct types of API tokens; Organizations, Teams, and Users. Each token type has distinct access levels and generation workflows. A given Vault role can manage any one of the three types at a time, however there are important differences to be aware of.

Organization and team roles

The HCP Terraform API limits both Organization and Team roles to one active token at any given time. Generating a new Organization or Team API token by reading the credentials in Vault or otherwise generating them on app.terraform.io will effectively revoke any existing API token for that Organization or Team.

Due to this behavior, Organization and Team API tokens created by Vault will be stored and returned on future requests, until the credentials get rotated. This is to prevent unintentional revocation of tokens that are currently in-use.

Below is an example of creating a Vault role to manage an Organization API token and rotating the token:

$ vault write terraform/role/testing organization="${TF_ORGANIZATION}"
Success! Data written to: terraform/role/testing

$ vault write -f terraform/rotate-role/testing
Success! Data written to: terraform/rotate-role/testing

The API token is retrieved by reading the credentials for the role:

$ vault read terraform/creds/testing
 
Key             Value
---             -----
organization    hashicorp-vault-testing
role            testing
token           <example token>
token_id        at-fqvtdTQ5kQWcjUfG

User roles

Traditionally, Vault secret engines create dynamic users and dynamic credentials along with them. At the time of writing, the HCP Terraform API does not allow for creating dynamic users. Instead, the HCP Terraform secret engine creates dynamic User API tokens by configuring a Vault role to manage an existing HCP Terraform user. The lifecycle of these tokens is managed by Vault and will auto expire according to the configured TTL and max TTL of the Vault role.

Below is an example of creating a Vault role to manage manage User API tokens:

$ vault write terraform/role/user-testing user_id="${TF_USER_ID}"
Success! Data written to: terraform/role/user-testing

The API token is retrieved by reading the credentials for the role:

$ vault read terraform/creds/user-testing
 
Key             Value
---             -----
role            user-testing
token           <example token>
token_id        at-fqvtdTQ5kQWcjUfG

Please see the HCP Terraform API Token documentation for more information.

Tutorial

Refer to HCP Terraform Secrets Engine for a step-by-step tutorial.

API

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