InternetDomainName.isValid is not RFC1123 compliant

[gissuebot]

Original issue created by manderson23 on 2014-10-27 at 10:59 PM

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InternetDomainName.isValid returns false for the parameter "8server".

RFC1123 suggests that names should be able to start with a digit. See https://groups.google.com/forum/#!topic/guava-discuss/8Sycya7Fkok on guava-discuss for a discussion of the issue.

I also asked for clarification on Server Fault at http://serverfault.com/questions/638260/is-it-valid-for-a-hostname-to-start-with-a-digit

My final suggestion on the mailing list for solving this was as follows:

"What about if the final part starts with a digit actually checking if the complete name is an IP address e.g. calling InetAddreses.isInetAddress? The discussion section in RFC 1123 does suggest a full syntactic check to prevent a dotted decimal number getting through."

but there was no response.

[tgpfeiffer]

I was directed here in a discussion of https://issues.cloudera.org/browse/DISTRO-638 ("Cannot install Cloudera Manager Agent if hostname starts with a digit") where the origin of that issue is that Docker generates hostnames as random hexadecimal strings, which do therefore quite often start with a digit. (And they refuse to change that, insisting that it is totally RFC-compliant to start with a digit, as long as there is also any normal letter in the hostname: moby/moby#7756, moby/moby#8194)

I would therefore very much like to see a change of behavior from "fail if first character of TLD is a digit" to "fail if all characters of TLD are digits".

[frank-dspeed]

tgpfeiffer there is a patch for that you can even patch it easy your self with simply adding a random letter fixed in front of the container name via editing docker src and making a fork