F37 proposal: Fallback Hostname (System-Wide Change proposal)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



https://fedoraproject.org/wiki/Changes/FallbackHostname

This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.

== Summary ==
This proposal is for the fallback hostname for server like variants of
Fedora to use `localhost` as the fallback hostname.

== Owner ==
* Name: [[User:dustymabe| Dusty Mabe]] (Fedora CoreOS)
* Email: dustymabe@xxxxxxxxxx
* Name: [[User:davdunc| David Duncan]] (Fedora Cloud)
* Email: davdunc@xxxxxxxxx
* Name: [[User:pwhalen| Paul Whalen]] (Fedora IoT)
* Email: pwhalen@xxxxxxxxxx
* Name: [[User:salimma| Michel Alexandre Salim]] (Fedora Server)
* Email: michel@xxxxxxxxxxxxxxx
* Name: [[User:ngompa| Neal Gompa]] (Fedora Workstation/KDE)
* Email: ngompa13@xxxxxxxxx


== Detailed Description ==

In Fedora 33 the default fallback hostname was changed from
`localhost` to `fedora` for Fedora Linux instances that didn't get the
hostname set in any other way (i.e. it's the fallback if it's not set
anywhere else). This change came in a systemd update and was never
proposed as a change in Fedora itself.

The enablement upstream was in
https://github.com/systemd/systemd/pull/5175 and the BZ requesting the
change in Fedora was
https://bugzilla.redhat.com/show_bug.cgi?id=1392925. The original
reasoning being that `localhost` is a bad hostname for auto-discovery
protocols (think `avahi`) that are useful for more desktop
applications.

Unfortunately, this caused issues because setting the hostname via
reverse DNS lookups (via NetworkManager) stopped working along with
breaking third party tools that set the hostname. The NetworkManager
problem was subsequently fixed, but it still remains that a lot of
third party software will check to see if an instance's hostname is
"unset" by checking the current hostname against the string
"localhost". Additionally it appears this change will never be picked
up by Fedora's primary downstream in CentOS/RHEL (see
https://src.fedoraproject.org/rpms/systemd/c/13d1341b108a24d13f5922054307b5c2efc6836a?branch=rawhide).

The proposal here is to enable variants of Fedora Linux to configure
their default/fallback hostname and to set the default for variants
targetting servers (Cloud, CoreOS, IoT, Server) to `localhost`.


== Benefit to Fedora ==
With this change Fedora's server-like variants will become more
compatible with third party tools that expect a hostname of
`localhost` means the system is unconfigured. It also will mean system
administrator's will see `localhost` and assume the hostname is
unconfigured.

== Scope ==
* Proposal owners:
The feature owners will update the systemd compile time switch for
fallback hostname back to `localhost`. The `fedora-release` package
will be updated such that the Fedora Server, IoT, Cloud, and CoreOS
editions will use `localhost` as the fallback hostname. All other
variants of Fedora (the ones that target desktop/laptop uses) will
default to `fedora` as the fallback hostname.

The proposed changes are a relatively small amount of a work.


* Other developers:
For any variants other than Cloud, CoreOS, IoT, and Server they will
see no change. Work with QA to verify other editions continue to have
a fallback hostname of `fedora`.

For Cloud, CoreOS, IoT, and Server the default fallback hostname would
be `localhost`.


* Release engineering: No changes needed for release engineering.

* Policies and guidelines: N/A (not needed for this Change)

* Trademark approval: N/A (not needed for this Change)

* Alignment with Objectives: N/A

== Upgrade/compatibility impact ==

There will be NO upgrade impact to systems where:

* An admin statically set the hostname
* A hostname was provided to a system via DHCP
* A hostname was found for a system via reverse DNS lookup

In the case where none of the above are true for a system (i.e. a
fallback hostname will be used) the following upgrade impact will be
observed:

* Fedora Cloud: No impact. A booted Fedora Cloud 36 instance has
`/etc/hostname` written by `cloud-init` on first boot.
* Fedora CoreOS: No impact. Already using `localhost` as fallback hostname.
* Fedora IoT: Some impact. The fallback hostname will change from
`fedora` to `localhost` after upgrade.
* Fedora Server: Some impact. The fallback hostname will change from
`fedora` to `localhost` after upgrade.

For Fedora IoT and Fedora Server we will announce the change and
encourage users to statically set a hostname for their machines if
they don't want the change in behavior.


== How To Test ==

Boot an instance of the flavor of Fedora you are testing in an
environment where there is no DHCP hostname provided and no answer to
a reverse DNS lookup for the instance IP. Run `hostnamectl hostname`
and verify that it matches expectation. For Fedora Cloud, CoreOS, IoT,
Server it should be `localhost`. For all others it should be `fedora`.

== User Experience ==
For Cloud, CoreOS, IoT and Server users will notice intances now
default to `localhost` if a hostname is not provided to an instance by
any other means. For all other variants of Fedora there will be no
change.

== Dependencies ==
There will be changes to the `systemd` and `fedora-release` packages
for this change.


== Contingency Plan ==
* Contingency mechanism: Revert the pull requests to the `systemd` and
`fedora-release` packages.
* Contingency deadline: Final Freeze
* Blocks release? Yes


== Documentation ==
The fallback hostname has now changed to `localhost` for the Cloud,
CoreOS, IoT, and Server variants of Fedora.

== Release Notes ==
The fallback hostname has now changed for the Cloud, CoreOS, IoT, and
Server editions of Fedora to `localhost`. The fallback hostname is the
hostname that is set if the hostname cannot be determined by any other
mechanism (statically set, DHCP, or reverse DNS). This change was done
in order to conform to the common expectation that a hostname of
`localhost` on a system means the hostname is "unset".


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis
_______________________________________________
devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx
Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Fedora Announce]     [Fedora Users]     [Fedora Kernel]     [Fedora Testing]     [Fedora Formulas]     [Fedora PHP Devel]     [Kernel Development]     [Fedora Legacy]     [Fedora Maintainers]     [Fedora Desktop]     [PAM]     [Red Hat Development]     [Gimp]     [Yosemite News]

  Powered by Linux