[Kea-announce] Kea 1.7.7, a new development release of Kea, is now available

Thu Apr 30 16:08:09 UTC 2020

Internet Systems Consortium is pleased to announce the release of Kea 1.7.7.

Kea releases are divided into two branch sequences:

1)  A current stable branch (currently 1.6.x) which receives only important
     bug fixes and is otherwise feature-stable, and

2)  An experimental development branch (currently 1.7.x) where new features
     are added and made available for testing during development, before eventually
     being included in the next stable release branch.

Kea 1.7.7 is the latest release in the experimental development branch.

Michael McNally
ISC Support

-----------------------

# Kea 1.7.7, April 29th 2020, Release Notes

Welcome to Kea 1.7.7, a monthly development release of Kea. This is the
first public release that offers multithreading support. As with any
other development release, use this with caution. Development releases
are not recommended for production use.

There are many changes introduced in this version:

1. **Multithreading**. Our work continues on MT support improvements.
The temporary command-line option -N has now been replaced with more
extensive configuration options defined in the configuration file:
`enable-multi-threading`, `thread-pool-size`, and `packet-queue-size`
#893. A problem that causes roughly 0.5% of DHCPv6 responses to not be
returned has been fixed #1158. The default logging now includes
thread-id #1150. A number of problems reported by thread sanitizer have
been fixed in the Control Agent #1094, libprocess #1096, and libutil
#1089. The socket control buffer is now kept on the stack #343. Finally,
a set of performance tests results has been
[published](https://kb.isc.org/docs/kea-performance-tests-17-multithreadi
ng). This may be of use for people interested in MT and performance, so
it's mentioned here.

2. **Prometheus exporter and Grafana template**. A new project is under
development: ISC Stork is a dashboard that provides Kea monitoring and
troubleshooting. It includes a Stork agent that provides Prometheus
exporter capability. You can run this agent to periodically retrieve
statistics from Kea and make them available in a format that Prometheus
can understand. Stork also includes a Grafana template that can be
easily imported into Grafana to visualize the data exported to
Prometheus. While technically Stork is a stand-alone project, it may be
perceived by many as a Kea extension. As such, it is mentioned in these
release notes #279, #280, #1191.

3. **Performance improvements**. Our team was able to address two small
performance improvements this month, in addition to all the MT work
mentioned earlier. MapElement is an internal representation of JSON and
is used in many places in the code; we improved how its instances are
compared #1187. Another improvement is related to statistics; under
certain circumstances, statistics were calculated multiple times. This
is now fixed #1162.

4. **Forensic logging**. The library can now print values as plain text
if the content is printable #949.

5. **Package improvements**. The RADIUS package now depends on host
cache #1157. A problem with Control Agent sometimes failing to start was
traced to a race condition between systemd scripts. The improved
dependency fixed the problem #1134.

6. **New Statistics**. Several new statistics have been implemented.
`cumulative-assigned-addresses` provides an ever-growing number of
leases that have been assigned. This can be used e.g. to monitor the
number of devices visiting a network daily. Similar statistics have also
been added for IPv6 addresses (`cumulative-assigned-nas`) and IPv6
prefixes (`cumulative-assigned-pds`). The statistics are available
globally and on a per-subnet basis #816.

7. **Leasequery**. The work on leasequery support is picking up. The
design is now complete #994 and the code is able to store more lease
parameters with the lease #1010. In the coming weeks, we will implement
the code to actually use that ability to return more detailed
information in leasequery responses.

8. **Notable bug fixes**. An unlikely MySQL InnoDB deadlock has been
fixed. While the possibility had existed for a long time, the deadlock
was unlikely to be triggered due to the single-threaded nature of
earlier Kea versions. With multithreading now available the likelihood
of triggering this problem was elevated, but the problem is now fixed
#1160. A problem with the RADIUS hook failing to start has been fixed
#1156. The Flex-id hook now has better sanity checks for misconfigured
expressions; previously, the hook loaded but then reported errors for
every incoming packet if the expression configured was incorrect #1083.
Another sporadically occurring problem with Kea-dhcp4 sometimes freezing
on start has been fixed. This one is related to how Linux handles LPF
sockets; if Kea opened a socket too early on an interface that wasn't
ready to receive traffic, the read operation on LPF socket could get
stuck in infinite wait #1151.

9. **Documentation** The multithreading section of the Kea ARM now
mentions MT parameters and its defaults #1192, and a section with
pointers to Stork has been added #1191. `lease4-get-page` and
`lease6-get-page` commands that were implemented some time ago now have
their documentation generated properly #882.

10. **Testing improvements**. Perfdhcp is now able to simulate traffic
coming in from multiple subnets. A new command-line option `-J` allows
passing a filename that contains IPv4 addresses of DHCP relays to be
simulated. Kea-dhcp4 can be forced to send back responses to the source
address of the incoming reply. While technically this violates the RFC
standard, it is very useful for testing #1132.

## Changes to Release Model
The Kea project has been in development for several years now, and it
has a significant production deployment base with users who are looking
for stability, rather than a constant stream of new "bleeding-edge"
features. At the same time, we want to continue developing the software
and add some new powerful, but difficult-to-implement, features. As a
result, we decided to change the release cycle. Starting from 1.6.0,
there are two branches: stable and development.

Stable releases are what you would expect: stable, released
infrequently, without new features or significant changes, very
well-tested. These can be identified by an even-numbered major version
number. The current stable release is 1.6.2, with a major version of
1.6, and minor version 2. If we discover important bugs that require
fixing, we may release 1.6.3, but that will be determined on a
case-by-case basis. The next major stable version will be 1.8.0,
followed by 2.0.0 in the future.

Our team continues development of new features. In particular, we're
tackling the difficult problem of being able to use all available CPU
cores simultaneously. The multithreading implementation is a complex
task and it is unknown how long it will take before the solution is
stable and ready for a production environment. At the same time, we
continue to receive a stream of requests for small features and bug
fixes. We don't want to force users to wait half a year or more for the
fixes and features that are already done. Therefore, we have started
issuing development releases on a monthly basis. Those are slightly less
well-tested and may have features that are not complete.

Development releases can be easily identified by an odd major version
number: for example, 1.7.7 is a development release. In June 2020 we
expect to release 1.7.8, the next development version. Once 1.8.0 is
out, we will continue our development work with 1.9.0, then 1.9.1, and
so on.

Our goal is to make the development release available on the last
Wednesday of each month. There may be exceptions (such as during
holidays), but that's the general plan.

We encourage users to test the development releases and report back
their findings.

For more details on the plan, see ISC's Software Support Policy at
https://kb.isc.org/docs/aa-00896.

## Kea overview
Kea is a DHCP implementation developed by Internet Systems Consortium,
Inc. that features fully functional DHCPv4 and DHCPv6 servers, a dynamic
DNS update daemon, a Control Agent (CA) that provides a REST API to
control the DHCP and DNS update servers, an example shell client to
connect to the CA, a daemon that is able to retrieve YANG configuration
and updates from Sysrepo, and a DHCP performance-measurement tool. Both
DHCP servers fully support server discovery, address assignment,
renewal, rebinding, release, decline, information request, DNS updates,
client classification, and host reservations. The DHCPv6 server also
supports prefix delegation. Lease information is stored in a CSV file by
default; it can optionally be stored in a MySQL, PostgreSQL, or
Cassandra database instead. Host reservations can be stored in a
configuration file, or in a MySQL, PostgreSQL, or Cassandra database.
They can also be retrieved from a RADIUS server, although this
functionality is somewhat limited. Kea DHCPv4 and DHCPv6 daemons provide
support for YANG models, which are stored in a Sysrepo datastore and can
be configured via the NETCONF protocol.

This text references issue numbers. For more details, visit the Kea
GitLab page at https://gitlab.isc.org/isc-projects/kea/issues.

## License
This version of Kea is released under the Mozilla Public License,
version 2.0.

   https://www.mozilla.org/en-US/MPL/2.0

The premium and subscriber-only hook libraries are provided in source
code form, under the terms of an End User License Agreement (you will
get the source code that you can modify freely, but you are not
permitted to redistribute it).

## Download
Pre-built ISC packages for current versions of the most popular Linux
operating systems are available at:

   https://cloudsmith.io/~isc/repos/

The Kea source and PGP signature for this release may be downloaded from:

   https://www.isc.org/download

The signature was generated with the ISC code signing key which is
available at:

   https://www.isc.org/pgpkey

ISC provides detailed documentation, including installation instructions
and usage tutorials, in the Kea Administrator Reference Manual.
Documentation is included with the installation, at
https://kea.readthedocs.io/en/latest/, or via
https://kb.isc.org/docs/kea-administrator-reference-manual in HTML,
plain text, or PDF formats. ISC maintains a public open source code
tree, a wiki, an issue tracking system, milestone planning, and a
roadmap at https://gitlab.isc.org/isc-projects/kea.

Limitations and known issues with this release can be found at
https://gitlab.isc.org/isc-projects/kea/wikis/known-issues-list.

We ask users of this software to please let us know how it worked for
you and what operating system you tested on. Feel free to share your
feedback on the Kea Users mailing list
(https://lists.isc.org/mailman/listinfo/kea-users).  Also we would like
to hear whether the documentation is adequate and accurate. Please open
tickets in the Kea GitLab project for bugs, documentation omissions and
errors, and enhancement requests. We want to hear from you even if
everything worked.

## Support
Professional support for Kea is available from ISC. We encourage all
professional users to consider this option; Kea development and
maintenance are funded with support subscriptions. For more information
on ISC's Kea and DHCP software support see https://www.isc.org/support/.

Free best-effort support is provided by our user community via a mailing
list. Information on all public email lists is available at
https://www.isc.org/community/mailing-list. If you have any comments or
questions about working with Kea, please share them to the Kea Users
List (https://lists.isc.org/mailman/listinfo/kea-users). Bugs and
feature requests may be submitted via GitLab at
https://gitlab.isc.org/isc-projects/kea/issues.

## Changes
The following summarizes changes and important upgrade notes since the
previous release (1.7.6).

1743.	[doc]		tomek
	ISC now provides a dashboard solution for Kea. Added
documentation
	pointers about the ISC Stork project.
	(Gitlab #1191)

1742.	[func]		fdupont
	Added new cumulative statistics: for each assigned IPv4 address,
	IPv6 NA address or IPv6 PD prefixes
cumulative-assigned-addresses,
	cumulative-assigned-nas or cumulative-assigned-pds global and
	per subnet is increased. A spelling error in the result-set of
	the stat-lease4-get of the stat cmds hook library was fixed.
	(Gitlab #816)

1741.	[func]		fdupont
	When the MySQL InnoDB reports a deadlock (very rare event)
	the failed query is rerun.
	(Gitlab #1160)

1740.	[bug]		fdupont
	Incorrect signal handling in the process library (used for
	control agent, d2 and netconf server but not by DHCPv4 or
	DHCPv6 servers) was replaced by the boost ASIO signal set.
	(Gitlab #1096)

1739.	[func]		razvan
	Added multi threading configuration parameters which can be used
	to adjust server performance according to setup resources and
needs:
	enable-multi-threading, thread-pool-size and packet-queue-size.
	There is also an automatic detection implemented by using
	thread-pool-size set to 0. However, the packet-queue-size must be
	manually configured and does not scale automatically.
	The temporary -N command line option was removed.
	The multi threading is disabled by default.
	(Gitlab #893)

1738.	[func]		fdupont
	Added new global parameters statistic-default-sample-count and
	statistic-default-sample-age to set the default values used
	for sample keeping limits.
	(Gitlab #1005)

1737.	[func]		tmark
	Added store-extended-info parameter to kea-dhcp4 and kea-dhcp6
	which enables the storage of additional information per lease.
	This has been added in anticipation of supporting LeaseQuery.
	(Gitlab #1010)

1736.	[doc]		fdupont
	A default logging syntax has been updated to reflect recently
added
	multi-threading capabilities. The process is now identified by
	name/process-id.thread-id, e.g. kea-dhcp4.dhcpsrv/8475.12345,
where
	12345 is the thread-id. Its exact syntax is OS dependent. The
	logging syntax can be tweaked using `pattern` option for logging.
	(Gitlab #1150)

Thank you again to everyone who assisted us in making this release
possible.

We look forward to receiving your feedback.