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docs Secret Backend: PostgreSQL docs-secrets-postgresql The PostgreSQL secret backend for Vault generates database credentials to access PostgreSQL.

PostgreSQL Secret Backend

Name: postgresql

The PostgreSQL secret backend 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 both of its own internal revocation system as well as the VALID UNTIL setting when creating PostgreSQL users to ensure that users become invalid within a reasonable time of the lease expiring.

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

The first step to using the PostgreSQL backend is to mount it. Unlike the generic backend, the postgresql backend is not mounted by default.

$ vault mount postgresql
Successfully mounted 'postgresql' at 'postgresql'!

Next, Vault must be configured to connect to the PostgreSQL. This is done by writing either a PostgreSQL URL or PG connection string:

$ vault write postgresql/config/connection \
    connection_url="postgresql://root:vaulttest@vaulttest.ciuvljjni7uo.us-west-1.rds.amazonaws.com:5432/postgres"

In this case, we've configured Vault with the user "root" and password "vaulttest", connecting to a PostgreSQL instance in AWS RDS. The "postgres" database name is being used. It is important that the Vault user have the GRANT OPTION privilege to manage users.

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

$ vault write postgresql/config/lease lease=1h lease_max=24h
Success! Data written to: postgresql/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 generated those credentials. For example, lets create a "readonly" role:

$ vault write postgresql/roles/readonly \
    sql="CREATE ROLE \"{{name}}\" WITH LOGIN PASSWORD '{{password}}' VALID UNTIL '{{expiration}}';
    GRANT SELECT ON ALL TABLES IN SCHEMA public TO \"{{name}}\";"
Success! Data written to: postgresql/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}}, {{password}} and {{expiration}} 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 PostgreSQL manual for more information.

To generate a new set of credentials, we simply read from that role: Vault is now configured to create and manage credentials for Postgres!

$ vault read postgresql/creds/readonly
Key           	Value
lease_id      	postgresql/creds/readonly/c888a097-b0e2-26a8-b306-fc7c84b98f07
lease_duration	3600
password      	34205e88-0de1-68b7-6267-72d8e32c5d3d
username      	root-1430162075-7887

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 postgresql backend such that trusted operators can manage the role definitions, and both users and applications are restricted in the credentials they are allowed to read.

If you get stuck at any time, simply run vault path-help postgresql or with a subpath for interactive help output.

API

/postgresql/config/connection

POST

Description
Configures the connection string used to communicate with PostgreSQL.
Method
POST
URL
`/postgresql/config/connection`
Parameters
  • connection_url required The PostgreSQL connection URL or PG style string. e.g. "user=foo host=bar"
  • value optional The PostgreSQL connection URL or PG style string. e.g. "user=foo host=bar". Use `connection_url` instead.
  • max_open_connections optional Maximum number of open connections to the database. A zero uses the default value of 2 and a negative value means unlimited.
    max_idle_connections optional Maximum number of idle connections to the database. A zero uses the value of `max_open_connections` and a negative value disables idle connections. If larger than `max_open_connections` it will be reduced to be equal.
    verify_connection optional If set, connection_url is verified by actually connecting to the database. Defaults to true.
Returns
A `204` response code.

/postgresql/config/lease

POST

Description
Configures the lease settings for generated credentials. If not configured, leases default to 1 hour. This is a root protected endpoint.
Method
POST
URL
`/postgresql/config/lease`
Parameters
  • lease required The lease value provided as a string duration with time suffix. Hour is the largest suffix.
  • lease_max required The maximum lease value provided as a string duration with time suffix. Hour is the largest suffix.
Returns
A `204` response code.

/postgresql/roles/

POST

Description
Creates or updates the role definition.
Method
POST
URL
`/postgresql/roles/`
Parameters
  • sql required The SQL statements executed to create and configure the role. Must be a semicolon-separated string, a base64-encoded semicolon-separated string, a serialized JSON string array, or a base64-encoded serialized JSON string array. The '{{name}}', '{{password}}' and '{{expiration}}' values will be substituted.
Returns
A `204` response code.

GET

Description
Queries the role definition.
Method
GET
URL
`/postgresql/roles/`
Parameters
None
Returns
```javascript
{
  "data": {
    "sql": "CREATE USER..."
  }
}
```

LIST

Description
Returns a list of available roles. Only the role names are returned, not any values.
Method
GET
URL
`/roles/?list=true`
Parameters
None
Returns
{
  "auth": null,
  "data": {
    "keys": ["dev", "prod"]
  },
  "lease_duration": 2592000,
  "lease_id": "",
  "renewable": false
}

DELETE

Description
Deletes the role definition.
Method
DELETE
URL
`/postgresql/roles/`
Parameters
None
Returns
A `204` response code.

/postgresql/creds/

GET

Description
Generates a new set of dynamic credentials based on the named role.
Method
GET
URL
`/postgresql/creds/`
Parameters
None
Returns
```javascript
{
  "data": {
    "username": "root-1430158508-126",
    "password": "132ae3ef-5a64-7499-351e-bfe59f3a2a21"
  }
}
```