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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 processes should connect to their localhost mongod with a standalone type of connection.

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


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

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"


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:

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


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


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 readConcernlocal
  • 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.

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Last update: July 11, 2024
Created: July 11, 2024