PostgreSQL database secrets engine

PostgreSQL is one of the supported plugins for the database secrets engine. This plugin generates database credentials dynamically based on configured roles for the PostgreSQL database, and also supports Static Roles.

See the database secrets engine docs for more information about setting up the database secrets engine.

The PostgreSQL secrets engine uses pgx, the same database library as the PostgreSQL storage backend. Connection string options, including SSL options, can be found in the pgx and PostgreSQL connection string documentation.

Capabilities

Setup

1. Enable the database secrets engine if it is not already enabled:

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

   By default, the secrets engine will enable at the name of the engine. To enable the secrets engine at a different path, use the -path argument.

2. Configure Vault with the proper plugin and connection information:

   $ vault write database/config/my-postgresql-database \
       plugin_name="postgresql-database-plugin" \
       allowed_roles="my-role" \
       connection_url="postgresql://{{username}}:{{password}}@localhost:5432/database-name" \
       username="vaultuser" \
       password="vaultpass" \
       password_authentication="scram-sha-256"
   

3. Configure a role that maps a name in Vault to an SQL statement to execute to create the database credential:

   $ vault write database/roles/my-role \
       db_name="my-postgresql-database" \
       creation_statements="CREATE ROLE \"{{name}}\" WITH LOGIN PASSWORD '{{password}}' VALID UNTIL '{{expiration}}'; \
           GRANT SELECT ON ALL TABLES IN SCHEMA public TO \"{{name}}\";" \
       default_ttl="1h" \
       max_ttl="24h"
   Success! Data written to: database/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.

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

   $ vault read database/creds/my-role
   Key                Value
   ---                -----
   lease_id           database/creds/my-role/2f6a614c-4aa2-7b19-24b9-ad944a8d4de6
   lease_duration     1h
   lease_renewable    true
   password           SsnoaA-8Tv4t34f41baD
   username           v-vaultuse-my-role-x
   

Rootless Configuration and Password Rotation for Static Roles

The PostgreSQL secrets engine supports using Static Roles and its password rotation mechanisms with a Rootless DB connection configuration. In this workflow, a static DB user can be onboarded onto Vault's static role rotation mechanism without the need of privileged root accounts to configure the connection. Instead of using a single root connection, multiple dedicated connections to the DB are made for each static role. This workflow does not support dynamic roles/credentials.

1. Enable the database secrets engine if it is not already enabled:

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

   By default, the secrets engine will enable at the name of the engine. To enable the secrets engine at a different path, use the -path argument.

2. Configure connection to DB without root credentials and enable the rootless workflow by setting the self_managed parameter:

   $ vault write database/config/my-postgresql-database \
       plugin_name="postgresql-database-plugin" \
       allowed_roles="my-role" \
       connection_url="postgresql://{{username}}:{{password}}@localhost:5432/database-name" \
       self_managed=true
   

3. Configure a static role that creates a dedicated connection to a user in the DB with the self_managed_password parameter:

   $ vault write database/static-roles/my-role \
     db_name="my-postgresql-database" \
     username="staticuser" \
     self_managed_password="password" \
     rotation_period="1h"
   

4. Read static credentials:

   $ vault read database/static-creds/my-role
   Key                    Value
   ---                    -----
   last_vault_rotation    2024-09-11T14:15:13.764783-07:00
   password               XZY42BVc-UO5bMsbgxrW
   rotation_period        1h
   ttl                    59m55s
   username               staticuser
   

Client x509 certificate authentication

This plugin supports using PostgreSQl's x509 Client-side Certificate Authentication.

To use this authentication mechanism, configure the plugin to consume the PEM-encoded TLS data inline from a file on disk by prefixing with the "@" symbol. This is useful in environments where you do not have direct access to the machine that is hosting the Vault server. For example:

$ vault write database/config/my-postgresql-database \
    plugin_name="postgresql-database-plugin" \
    allowed_roles="my-role" \
    connection_url="postgresql://{{username}}:{{password}}@localhost:5432/database-name?sslmode=verify-full" \
    username="vaultuser" \
    private_key=@/path/to/client.key \
    tls_certificate=@/path/to/client.pem \
    tls_ca=@/path/to/client.ca

Note: private_key, tls_certificate, and tls_ca map to sslkey, sslcert, and sslrootcert configuration options from PostgreSQL with the exception that the Vault parameters are the contents of those files, not filenames.

Alternatively, you can configure certificate authentication in environments where the TLS certificate data is present on the machine that is running the Vault server process. Set sslmode to be any of the applicable values as outlined in the PostgreSQL documentation and set the SSL credentials in the sslrootcert, sslcert and sslkey connection parameters as paths to files. For example:

$ export SSL="sslmode=verify-full&sslrootcert=/path/to/ca.pem&sslcert=/path/to/client.pem&sslkey=/path/to/client.key"
$ vault write database/config/my-postgresql-database \
    plugin_name="postgresql-database-plugin" \
    allowed_roles="my-role" \
    connection_url="postgresql://{{username}}:{{password}}@localhost:5432/database-name?sslmode=verify-full&${SSL}" \
    username="vaultuser"

API

The full list of configurable options can be seen in the PostgreSQL database plugin API page.

For more information on the database secrets engine's HTTP API please see the Database secrets engine API page.

Authenticating to Cloud DBs via IAM

Google Cloud

Aside from IAM roles denoted by Google's CloudSQL documentation, the following SQL privileges are needed by the service account's DB user for minimum functionality with Vault. Additional privileges may be needed depending on the SQL configured on the database roles.

-- Enable service account to create roles within DB
ALTER USER "<YOUR DB USERNAME>" WITH CREATEROLE;

Setup

1. Enable the database secrets engine if it is not already enabled:

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

   By default, the secrets engine will enable at the name of the engine. To enable the secrets engine at a different path, use the -path argument.

2. Configure Vault with the proper plugin and connection information. Here you can explicitly enable GCP IAM authentication and use Application Default Credentials to authenticate:

   $ vault write database/config/my-postgresql-database \
       plugin_name="postgresql-database-plugin" \
       allowed_roles="my-role" \
       connection_url="host=project:us-west1:mydb user=test-user@project.iam dbname=postgres sslmode=disable" \
       use_private_ip="false" \
       auth_type="gcp_iam"
   

   You can also configure the connection and authenticate by directly passing in the service account credentials as an encoded JSON string:

   $ vault write database/config/my-postgresql-database \
       plugin_name="postgresql-database-plugin" \
       allowed_roles="my-role" \
       connection_url="host=project:region:instance user=test-user@project.iam dbname=postgres sslmode=disable" \
       use_private_ip="false" \
       auth_type="gcp_iam" \
       service_account_json="@my_credentials.json"
   

Once the connection has been configured and IAM authentication is complete, the steps to set up a role and generate credentials are the same as the ones listed above.