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
Insecure	http-server.authentication.insecure.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.

• case (optional): one of:

  • keep - keep matched user name as is (default behavior)

  • lower - lowercase matched user name, e.g., Admin or ADMIN will become admin

  • upper - uppercase matched user name, e.g., admin or Admin will become ADMIN

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}"
        },
        {
            "pattern": "(.*)@uppercase.com",
            "case": "upper"
        }
    ]
}

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
Insecure	http-server.authentication.insecure.user-mapping.file