PostgreSQL configuration for Vault backend storage

The PostgreSQL storage backend is used to persist Vault's data in a PostgreSQL server or cluster.

• High Availability – the PostgreSQL storage backend supports high availability. Requires PostgreSQL 9.5 or later.

• Community Supported – the PostgreSQL storage backend is supported by the community. While it has undergone review by HashiCorp employees, they may not be as knowledgeable about the technology. If you encounter problems with them, you may be referred to the original author.

storage "postgresql" {
  connection_url = "postgres://user123:secret123!@localhost:5432/vault"
}

The PostgreSQL storage backend does not automatically create the table. Here is some sample SQL to create the schema and indexes.

CREATE TABLE vault_kv_store (
  parent_path TEXT COLLATE "C" NOT NULL,
  path        TEXT COLLATE "C",
  key         TEXT COLLATE "C",
  value       BYTEA,
  CONSTRAINT pkey PRIMARY KEY (path, key)
);

CREATE INDEX parent_path_idx ON vault_kv_store (parent_path);

Store for HAEnabled backend

CREATE TABLE vault_ha_locks (
  ha_key                                      TEXT COLLATE "C" NOT NULL,
  ha_identity                                 TEXT COLLATE "C" NOT NULL,
  ha_value                                    TEXT COLLATE "C",
  valid_until                                 TIMESTAMP WITH TIME ZONE NOT NULL,
  CONSTRAINT ha_key PRIMARY KEY (ha_key)
);

If you're using a version of PostgreSQL prior to 9.5, create the following function:

CREATE FUNCTION vault_kv_put(_parent_path TEXT, _path TEXT, _key TEXT, _value BYTEA) RETURNS VOID AS
$$
BEGIN
    LOOP
        -- first try to update the key
        UPDATE vault_kv_store
          SET (parent_path, path, key, value) = (_parent_path, _path, _key, _value)
          WHERE _path = path AND key = _key;
        IF found THEN
            RETURN;
        END IF;
        -- not there, so try to insert the key
        -- if someone else inserts the same key concurrently,
        -- we could get a unique-key failure
        BEGIN
            INSERT INTO vault_kv_store (parent_path, path, key, value)
              VALUES (_parent_path, _path, _key, _value);
            RETURN;
        EXCEPTION WHEN unique_violation THEN
            -- Do nothing, and loop to try the UPDATE again.
        END;
    END LOOP;
END;
$$
LANGUAGE plpgsql;

postgresql parameters

• connection_url (string: <required>) – Specifies the connection string to use to authenticate and connect to PostgreSQL. The connection URL can also be set using the VAULT_PG_CONNECTION_URL environment variable. A full list of supported parameters can be found in the pgx library and PostgreSQL connection string documentation. For example connection string URLs, see the examples section below.

• table (string: "vault_kv_store") – Specifies the name of the table in which to write Vault data. This table must already exist (Vault will not attempt to create it).

• max_idle_connections (int) - Default not set. Sets the maximum number of connections in the idle connection pool. See golang docs on SetMaxIdleConns for more information. Requires 1.2 or later.

• max_parallel (string: "128") – Specifies the maximum number of concurrent requests to PostgreSQL.

• ha_enabled (string: "true|false") – Default not enabled, requires 9.5 or later.

• ha_table (string: "vault_ha_locks") – Specifies the name of the table to use for storing high availability information. This table must already exist (Vault will not attempt to create it).

• auth_mode (string: "standard|aws_iam|azure_msi|gcp_iam") - Defaults to standard auth. For mode details, see the cloud authentication section below.

• aws_db_region (string: "") - Specifies the AWS region where DB is situated. Required when auth_mode is set to aws_iam

• azure_client_id (string: "") - Client ID of a user-assigned Managed Service Identity in Azure. System-assigned Managed Service Identity is used if azure_client_id is not provided and auth_mode is set to azure_msi.

postgresql examples

Custom SSL verification

This example shows connecting to a PostgreSQL cluster using full SSL verification (recommended).

storage "postgresql" {
  connection_url = "postgres://user:pass@localhost:5432/database?sslmode=verify-full"
}

To disable SSL verification (not recommended), replace verify-full with disable:

storage "postgresql" {
  connection_url = "postgres://user:pass@localhost:5432/database?sslmode=disable"
}

Authentication in cloud via cloud identities

AWS IAM

You can authenticate to your DB instance using AWS Identity and Access Management (IAM) database authentication. For more information please see the AWS documentation. AWS default credentials is used for authentication.

storage "postgresql" {
  connection_url  = "postgres://iam_user@db.xx.us-west-2.rds.amazonaws.com:5432/database?sslmode=require"
  auth_mode       = "aws_iam"
  aws_db_region   = "us-west-2"
}

Azure MSI

You can use both system-assigned and user-assigned managed identities to authenticate to Azure Database for PostgreSQL flexible server. For more information please see the Azure documentation.

storage "postgresql" {
  connection_url  = "postgres://msi_user@server.postgres.database.azure.com:5432/database?sslmode=require"
  auth_mode       = "azure_msi"
}

GCP IAM

You can use Google Cloud Identity and Access Management (IAM) to authenticate with Cloud SQL resources. For more information please see the Google documentation. Application Default Credentials is used for authentication.

storage "postgresql" {
  connection_url    = "postgres://iam-sa@xxxx.iam@203.0.113.0:5432/database?sslmode=require"
  auth_mode         = "gcp_iam"
}