Authentication

Percona Backup for MongoDB has no authentication and authorization subsystem of its own —— it uses that of MongoDB. This means that pbm CLI and pbm-agent require only a valid MongoDB connection URI string for the pbm user.

For the S3-compatible remote storage authentication config, see Percona Backup for MongoDB configuration in a cluster (or non-sharded replica set).

MongoDB connection strings

Percona Backup for MongoDB uses MongoDB Connection URI strings to open MongoDB connections. Neither pbm CLI nor pbm-agent accept legacy-style command-line arguments for --host, --port, --user, --password, etc. as the mongo shell or mongodump command does.

The pbm-agent connection stringThe pbm CLI connection string

The pbm-agent processes should connect to their localhost mongod with a standalone type of connection.

pbm-agent --mongodb-uri "mongodb://pbmuser:secretpwd@localhost:27017/?authSource=admin"

Alternatively:

export PBM_MONGODB_URI="mongodb://pbmuser:secretpwd@localhost:27017/?authSource=admin"
pbm-agent

Replace the pbmuser:secretpwd with the credentials of the user who owns the pbm process.

pbm status --mongodb-uri "mongodb://pbmuser:secretpwd@mongocsvr1:27017,mongocsvr2:27017,mongocsvr3:27017/?replicaSet=configrs&authSource=admin"

Alternatively:

export PBM_MONGODB_URI="mongodb://pbmuser:secretpwd@mongocsvr1:27017,mongocsvr2:27017,mongocsvr3:27017/?replicaSet=configrs&authSource=admin"
$ pbm status

Replace the pbmuser:secretpwd with the credentials of the user who owns the pbm process

The pbm CLI will ultimately connect to the replica set with PBM Control Collections.

• In a non-sharded replica set it is simply that replica set.
• In a cluster it is the config server replica set.

You do not necessarily have to provide that connection string. If you provide a connection to any live node (shard, configsvr, or non-sharded replica set member), pbm CLI will automatically determine the right hosts and establish a new connection to those instead.

The connection URI above is the format that MongoDB drivers have accepted universally since approximately the release time of MongoDB server v3.6. The mongo shell has accepted it too since v4.0. Using a v4.0+ mongo shell is a recommended way to debug connection URI validity from the command line.

Since Percona Backup for MongoDB must authenticate in MongoDB, we recommend specifying the authentication database associated with the pbm user’s credentials in the connection URI string using the authSource option.

The MongoDB Connection URI specification also allows specifying the authentication database via the defaultauthdb component. However, in this case, Percona Backup for MongoDB makes a backup of only this specified database.

If both authSource and defaultauthdb are unspecified, the authentication database defaults to the admin database.

The MongoDB Connection URI specification includes several non-default options you may need to use. For example, the TLS certificates/keys needed to connect to a cluster or non-sharded replica set with network encryption enabled are “tls=true” plus “tlsCAFile” and/or “tlsCertificateKeyFile” (see tls options).

Read Concern / Write Concern configuration

Version added: 2.5.0

By default, PBM requires the majority level of acknowledgement among replica set members for read and write operations in MongoDB. This level is controlled by readConcern and writeConcern settings.

If your cluster loses majority or is configured to operate without it, you can decrease the level for readConcern and writeConcern so that PBM remains operational and can make backups.

Specify new values in MongoDB connection URI string as follows:

The pbm-agent connection stringThe pbm CLI connection string

pbm-agent --mongodb-uri "mongodb://pbmuser:secretpwd@localhost:27017/?authSource=admin&readConcernLevel=local&w=1"

Alternatively:

export PBM_MONGODB_URI="mongodb://pbmuser:secretpwd@localhost:27017/?authSource=admin&readConcernLevel=local&w=1"
pbm-agent

pbm status --mongodb-uri "mongodb://pbmuser:secretpwd@mongocsvr1:27017,mongocsvr2:27017,mongocsvr3:27017/?replicaSet=configrs&authSource=admin&readConcernLevel=local&w=1"

Alternatively:

export PBM_MONGODB_URI="mongodb://pbmuser:secretpwd@mongocsvr1:27017,mongocsvr2:27017,mongocsvr3:27017/?replicaSet=configrs&authSource=admin&readConcernLevel=local&w=1"
$ pbm status

Supported values are:

• For readConcern – local
• For writeConcern – the number of nodes to acknowledge writes. A zero value is not supported.

For correct functioning of PBM, we recommend to change values for both options.

To restore from a backup, first configure your cluster to have the majority. Then make a restore.

External authentication support in Percona Backup for MongoDB

In addition to SCRAM, Percona Backup for MongoDB supports other authentication methods that you use in MongoDB or Percona Server for MongoDB.

For external authentication, you create the pbm user in the format used by the authentication system and set the MongoDB connection URI string to include both the authentication method and authentication source.

Kerberos

For Kerberos authentication , create the pbm user in the $external database in the format <username@KERBEROS_REALM> (e.g. pbm@PERCONATEST.COM).

Specify the following string for MongoDB connection URI:

PBM_MONGODB_URI="mongodb://<username>%40<KERBEROS_REALM>@<hostname>:27018/?authMechanism=GSSAPI&authSource=%24external&replSetName=xxxx"

Note that you must first obtain the ticket for the pbm user with the kinit command before you start the pbm-agent:

$ sudo -u {USER} kinit pbm

Note that the {USER} is the user that you will run the pbm-agent process.

LDAP binding

For authentication and authorization via Native LDAP , you only create roles for LDAP groups in MongoDB as the users are stored and managed on the LDAP server. However, you still define the $external database as your authentication source:

PBM_MONGODB_URI="mongodb://<user>:<password>@<hostname>:27017/?authMechanism=PLAIN&authSource=%24external&replSetName=xxxx"

AWS IAM

When using AWS IAM authentication , create the pbm user in the $external database with the username that contains the ARN of the IAM user/role.

User authentication Role authentication

arn:aws:iam::<ARN>:user/<user_name>

arn:aws:iam::<ARN>:role/<role_name>

The MongoDB connection URI string then looks like the following:

PBM_MONGODB_URI="mongodb://<aws_access_key_id>:<aws_secret_access_key>@<hostname>:27017/?authMechanism=MONGODB-AWS&authSource=%24external&replSetName=xxxx"

AWS EKS

If Percona Backup for MongoDB runs in Amazon Elastic Kubernetes Service (EKS) (e.g. as Percona Operator for MongoDB), it accesses the AWS S3 storage and other services using the credentials stored in the IAM role associated with the service account in EKS and assigned to the Pod where Percona Backup for MongoDB is deployed.

This saves you from creating and passing the AWS credentials to Pods explicitly thus increasing the overall security of your deployment.

To learn more about managing access to EKS, see Learn how EKS Pod Identity grants pods access to AWS services .

For how to configure Percona Operator for MongoDB to use AWS S3 storage, refer to the Configure storage for backups documentation.

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Last update: October 30, 2024
Created: October 30, 2024