6.5. User Mapping#

User mapping defines rules for mapping from users in the authentication system to Presto users. This mapping is particularly important for Kerberos or certificate authentication where the user names are complex like alice@example or CN=Alice Smith, OU=Finance, O=Acme, C=US.

User mapping can be configured with a simple regex extraction pattern, or more complex rules in a separate configuration file.

Pattern Mapping Rule#

The pattern mapping rule maps the authentication user to the first matching group in the regular expression. If the regular expression does not match the authentication user, authentication is denied.

Each authentication system has a separate property for the user mapping pattern to allow different mapping when multiple authentication systems are enabled:

Authentication

Property

Username and Password (file or LDAP)

http-server.authentication.password.user-mapping.pattern

Kerberos

http-server.authentication.krb5.user-mapping.pattern

Certificate

http-server.authentication.certificate.user-mapping.pattern

Json Web Token

http-server.authentication.jwt.user-mapping.pattern

File Mapping Rules#

The file mapping rules allow for more complex mappings from the authentication user. These rules are loaded from a JSON file defined in a configuration property. The mapping is based on the first matching rule, processed from top to bottom. If no rules match, authentication is denied. Each rule is composed of the following fields:

  • pattern (required): regex to match against authentication user.

  • user (optional): replacement string to substitute against pattern. The default value is $1.

  • allow (optional): boolean indicating if the authentication should be allowed.

The following example maps all users like alice@example.com to just alice, except for the test user which is denied authentication, and it maps users like bob@uk.example.com to bob_uk:

{
    "rules": [
        {
            "pattern": "test@example\\.com",
            "allow": false
        },
        {
            "pattern": "(.+)@example\\.com"
        },
        {
            "pattern": "(?<user>.+)@(?<region>.+)\\.example\\.com",
            "user": "${user}_${region}"
        }
    ]
}

Each authentication system has a separate property for the user mapping file to allow different mapping when multiple authentication systems are enabled:

Authentication

Property

Username and password (file or LDAP)

http-server.authentication.password.user-mapping.file

Kerberos

http-server.authentication.krb5.user-mapping.file

Certificate

http-server.authentication.certificate.user-mapping.file

Json Web Token

http-server.authentication.jwt.user-mapping.file