» MySQL Secrets Engine

Name: mysql

The MySQL secrets engine for Vault generates database credentials dynamically based on configured roles. This means that services that need to access a database no longer need to hardcode credentials: they can request them from Vault, and use Vault's leasing mechanism to more easily roll keys.

Additionally, it introduces a new ability: with every service accessing the database with unique credentials, it makes auditing much easier when questionable data access is discovered: you can track it down to the specific instance of a service based on the SQL username.

Vault makes use of its own internal revocation system to ensure that users become invalid within a reasonable time of the lease expiring.

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

» Quick Start

The first step to using the mysql secrets engine is to mount it. Unlike the kv secrets engine, the mysql secrets engine is not mounted by default.

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

Next, we must configure Vault to know how to connect to the MySQL instance. This is done by providing a DSN (Data Source Name):

$ vault write mysql/config/connection \
    connection_url="root:root@tcp(192.168.33.10:3306)/"
Success! Data written to: mysql/config/connection

In this case, we've configured Vault with the user "root" and password "root, connecting to an instance at "192.168.33.10" on port 3306. It is not necessary that Vault has the root user, but the user must have privileges to create other users, namely the GRANT OPTION privilege.

For using UNIX socket use: root:root@unix(/path/to/socket)/.

Optionally, we can configure the lease settings for credentials generated by Vault. This is done by writing to the config/lease key:

$ vault write mysql/config/lease \
    lease=1h \
    lease_max=24h
Success! Data written to: mysql/config/lease

This restricts each credential to being valid or leased for 1 hour at a time, with a maximum use period of 24 hours. This forces an application to renew their credentials at least hourly, and to recycle them once per day.

The next step is to configure a role. A role is a logical name that maps to a policy used to generate those credentials. For example, lets create a "readonly" role:

$ vault write mysql/roles/readonly \
    sql="CREATE USER '{{name}}'@'%' IDENTIFIED BY '{{password}}';GRANT SELECT ON *.* TO '{{name}}'@'%';"
Success! Data written to: mysql/roles/readonly

By writing to the roles/readonly path we are defining the readonly role. This role will be created by evaluating the given sql statements. By default, the {{name}} and {{password}} fields will be populated by Vault with dynamically generated values. This SQL statement is creating the named user, and then granting it SELECT or read-only privileges to tables in the database. More complex GRANT queries can be used to customize the privileges of the role. See the MySQL manual for more information.

To generate a new set of credentials, we simply read from that role:

$ vault read mysql/creds/readonly
Key               Value
---               -----
lease_id          mysql/creds/readonly/bd404e98-0f35-b378-269a-b7770ef01897
lease_duration    3600
password          132ae3ef-5a64-7499-351e-bfe59f3a2a21
username          readonly-aefa635a-18

By reading from the creds/readonly path, Vault has generated a new set of credentials using the readonly role configuration. Here we see the dynamically generated username and password, along with a one hour lease.

Using ACLs, it is possible to restrict using the mysql secrets engine such that trusted operators can manage the role definitions, and both users and applications are restricted in the credentials they are allowed to read.

Optionally, you may configure both the number of characters from the role name that are truncated to form the display name portion of the mysql username interpolated into the {{name}} field: the default is 10.

You may also configure the total number of characters allowed in the entire generated username (the sum of the display name and uuid portions); the default is 16. Note that versions of MySQL prior to 5.8 have a 16 character total limit on user names, so it is probably not safe to increase this above the default on versions prior to that.

» API

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