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Status
Current state: ["Under Discussion"]
Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]
JIRA: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
From Kafka documentation
"By default, the SASL user name will be the primary part of the Kerberos principal. One can change that by
setting sasl.kerberos.principal.to.local.rules to a customized rule in server.properties. The format of
sasl.kerberos.principal.to.local.rules is a list where each rule works in the same way as
the auth_to_local in Kerberos configuration file (krb5.conf)Each rules starts with RULE: and contains an expression in the format [n:string](regexp)s/pattern/replacement/g."
Currently, username translations based on rules are done maintaining the case of the input principal. For example, given the rule
"RULE:[2:$1@$0](.*@EXAMPLE.COM)s/@.*//"
If the source string is joe-qa/host@EXAMPLE.COM, the result is joe-qa If the source string is JOE-QA/host@EXAMPLE.COM, the result is JOE-QA If the source string is Joe-QA/host@EXAMPLE.COM, the result is Joe-QA
However, this may not be desired given how different operating system handle usernames, whereas some are case-sensitive
and some are case-insensitive. For example, Linux is case-sensitive and Windows is case-insensitive.
To help with this issue, the rule can support to force the translated result to be all lower case.
Reference
Proposed Changes
extend "sasl.kerberos.principal.to.local.rules" config rule format by supporting "/L" (toLowerCase) at the end of the rule. However, it must be noted that this does not affect how pattern matches on input and therefore that will still be case-sensitive.
RULE:[1:$1@$0](joe-qa-.*@EXAMPLE.COM)s/.*/JOE-QA//L RULE:[1:$1@$0](JOE-QA-.*@EXAMPLE.COM)s/.*/JOE-QA-UPPER//L RULE:[1:$1@$0](.*@EXAMPLE.COM)s/@.*///L
If the source string is joe-qa-cl1@EXAMPLE.COM, the result is joe-qa If the source string is JOE-QA-cl1@EXAMPLE.COM, the result is joe-qa-upper If the source string is joe_user@EXAMPLE.COM, the result is joe_user If the source string is JOE_USER@EXAMPLE.COM, the result is joe_use
Compatibility, Deprecation, and Migration Plan
This is an extension to the existing sasl.kerberos.principal.to.local.rules format and there will be no impact on existing users.
Rejected Alternatives
If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.