HashiCorp Vault integration¶

Percona Server for MongoDB is integrated with HashiCorp Vault. HashiCorp Vault supports different secrets engines. Percona Server for MongoDB only supports the HashiCorp Vault back end with KV Secrets Engine - Version 2 (API) with versioning enabled.

HashiCorp Vault parameters¶

Command line	Configuration file	Type	Description
vaultServerName	security.vault.serverName	string	The IP address of the Vault server
vaultPort	security.vault.port	int	The port on the Vault server
vaultTokenFile	security.vault.tokenFile	string	The path to the vault token file. The token file is used by MongoDB to access HashiCorp Vault. The vault token file consists of the raw vault token and does not include any additional strings or parameters. Example of a vault token file: `s.uTrHtzsZnEE7KyHeA797CkWA`
vaultSecret	security.vault.secret	string	The path to the Vault secret. The Vault secret path format must be `<secrets_engine_mount_path>/data/<custom_path>` where: - `<secrets_engine_mount_path>` is the path to the Key/Value Secrets Engine v2; - `data` is the mandatory path prefix required by Version 2 API; - `<custom_path>` is the path to the specific secret. Example: `secret_v2/data/psmdb-test/rs1-27017` Starting with version 5.0.15-13, a distinct Vault secret path for every replica set member is no longer mandatory. In earlier versions, it is recommended to use different secret paths for every database node in the entire deployment to avoid issues during the master key rotation.
vaultSecretVersion	security.vault. secretVersion	unsigned long	(Optional) The version of the Vault secret to use
vaultRotateMasterKey	security.vault. rotateMasterKey	switch	When enabled, rotates the master key and exits
vaultServerCAFile	security.vault. serverCAFile	string	The path to the TLS certificate file
vaultDisableTLSForTesting	security.vault. disableTLSForTesting	switch	Disables secure connection to Vault using SSL/TLS client certificates
vaultCheckMaxVersions	security.vault. checkMaxVersions	boolean	Verifies that the current number of secret versions has not reached the maximum, defined by the `max_versions` parameter for the secret or the secrets engine on the Vault server. If the number of versions has reached the maximum, the server logs an error and exits. Enabled by default. Available starting with version 5.0.29-25.

Config file example¶

security:
  enableEncryption: true
  vault:
    serverName: 127.0.0.1
    port: 8200
    tokenFile: /home/user/path/token
    secret: secret/data/hello

Vault access policy configuration¶

Starting with 5.0.29-25, Percona Server for MongoDB checks the number of the secrets on the Vault server before adding a new one thus preventing the loss of the old master key. For these checks, Percona Server for MongoDB requires read permissions for the secret’s metadata and the secrets engine configuration. You configure these permissions within the access policy on the Vault server.

Find the sample policy configuration below:

path "secret/data/*" {
  capabilities = ["create","read","update","delete"]
}
path "secret/metadata/*" {
  capabilities = ["read"]
}
path "secret/config" {
  capabilities = ["read"]
}

During the first run of the Percona Server for MongoDB, the process generates a secure key and writes the key to the vault.

During the subsequent start, the server tries to read the master key from the vault. If the configured secret does not exist, vault responds with HTTP 404 error.

Namespaces¶

Namespaces are isolated environments in Vault that allow for separate secret key and policy management.

You can use Vault namespaces with Percona Server for MongoDB. Specify the namespace(s) for the security.vault.secret option value as follows:

<namespace>/secret/data/<secret_path>

For example, the path to secret keys for namespace test on the secrets engine secret will be test/secret/<my_secret_path>.

Targeting a namespace in Vault configuration¶

You have the following options of how to target a particular namespace when configuring Vault:

Set the VAULT_NAMESPACE environment variable so that all subsequent commands are executed against that namespace. Use the following command to set the environment variable for the namespace test:

$ export VAULT_NAMESPACE=test

2. Provide the namespace with the --namespace flag in commands

Key rotation¶

Key rotation is replacing the old master key with a new one. This process helps to comply with regulatory requirements.

To rotate the keys for a single mongod instance, do the following:

Stop the mongod process
Add --vaultRotateMasterKey option via the command line or security.vault.rotateMasterKey to the config file.
Run the mongod process with the selected option, the process will perform the key rotation and exit.
Remove the selected option from the startup command or the config file.
Start mongod again.

Rotating the master key process also re-encrypts the keystore using the new master key. The new master key is stored in the vault. The entire dataset is not re-encrypted.

Key rotation in replica sets¶

Starting with version 5.0.15-13, you can store the master key at the same path on every replica set member in your entire deployment. Vault assigns different versions to the master keys stored at the same path. The path and the version serve as the unique identifier of a master key. The mongod server stores that identifier and uses it to retrieve the correct master key from the Vault server during the restart.

In versions 5.0.14-12 and earlier, every mongod node in a replica set in your entire deployment must have a distinct path to the master keys on a Vault server.

The key rotation steps are the following:

Rotate the master key for the secondary nodes one by one.
Step down the primary and wait for another primary to be elected.
Rotate the master key for the previous primary node.

Master key loss prevention¶

Starting with version 5.0.29-25, Percona Server for MongoDB checks if the number of secret versions has reached the maximum (10 by default) before adding a new master key to the Vault server as a versioned secret. You configure this number using the max_versions parameter on the Vault server.

If the number of secrets reaches the maximum, Percona Server for MongoDB logs an error and exits. This prevents the Vault server from dropping the oldest secret version and the encryption key it stores.

To continue, increase the maximum versions for the secret or the entire secrets engine on the Vault server, then restart Percona Server for MongoDB. To check the number of secrets on the Vault server, ensure Percona Server for MongoDB has read permissions for the secret’s metadata and the secrets engine configuration.

Upgrade considerations¶

After upgrading to Percona Server for MongoDB 5.0.29-25, configure the read permissions for it within the access policy on the Vault server. These permissions are required to check for the number of secrets versions to prevent the master key loss.

See the policy configuration example.

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Version	Description
5.0.15-13	Key rotation in replica sets
5.0.29-25	Master key loss prevention