[Freeipa-devel] NTP in FreeIPA

[Martin Basti]

On 24.11.2016 07:06, David Kupka wrote:
> On 22/11/16 23:15, Gabe Alford wrote:
>> I would say that it is worth keeping in FreeIPA. I know myself and some
>> customers use its functionality by having the clients sync to the IPA
>> servers and have the servers sync to the NTP source. This way if the NTP
>> source ever gets disrupted for long periods of time (which has 
>> happened in
>> my environment) the client time drifts with the authentication 
>> source. This
>> is the way that AD often works and is configured.
>
> Hello Gabe,
> I agree that it's common practice to synchronize all nodes in network 
> with single source in order to have the same time and save bandwidth. 
> Also I understand that it's comfortable to let FreeIPA installer take 
> care of it.
> But I don't think FreeIPA should do it IMO this is job for Ansible or 
> similar tool. Also the problem is that in some situations FreeIPA 
> installer makes it worse.
>
> Example:
>
> 1. Install FreeIPA server (ipa1.example.org)
> 2. Install FreeIPA client on all nodes in network
> 3. Install replica (ipa2.example.org) of FreeIPA server to increase 
> redundancy
>
> Now all the clients have ipa1.example.org as the only server in 
> /etc/ntp.conf. If the first FreeIPA server becomes unreachable all 
> clients will be able to contact KDC on the other server thanks to DNS 
> autodiscovery in libkrb5 but will be unable to synchronize time.
>

This can be resolved by DHCP configured NTP. When NTP server changed, 
you just change DHCPd config and hosts conf will be synced.
We may keep NTP on IPA server side configured, but I'm voting for 
removing it from clients and document+endorse people to use DHCP (anyway 
distros have always enabled some time synchronization so it should 
naturally work without even in small deployments)

Also NTP is somehow incompatible with containers, usually containers 
have time synchronized from host, and by default IPA client container 
don't do NTP configuration.

Let deprecate it in 4.5

Martin^2


>>
>> On Tue, Nov 22, 2016 at 7:05 AM, Jan Cholasta <jcholast at redhat.com> 
>> wrote:
>>
>>> On 22.11.2016 13:06, Petr Spacek wrote:
>>>
>>>> On 22.11.2016 12:15, David Kupka wrote:
>>>>
>>>>> Hello everyone!
>>>>>
>>>>> Is it worth to keep configuring NTP in FreeIPA?
>>>>>
>>>>> In usual environment there're no special requirements for time
>>>>> synchronization
>>>>> and the distribution default (be it ntpd, chrony or anything else) 
>>>>> will
>>>>> just
>>>>> work. Any tampering with the configuration can't make it any better.
>>>>>
>>>>> In environment with special requirements (network disconnected from
>>>>> public
>>>>> internet, nodes disconnected from topology for longer time, ...) time
>>>>> synchronization must be taken care of accordingly by system
>>>>> administrator and
>>>>> FreeIPA simply can't help here.
>>>>>
>>>>> Also there are problems and weird behavior with the current FreeIPA
>>>>> installers:
>>>>>
>>>>> * ipa-client-install replaces all servers in /etc/ntp.conf with 
>>>>> the ones
>>>>> specified by user or resolved from DNS. If none were provided nor
>>>>> resolved the
>>>>> FreeIPA server specified/resolved during installation it used. This
>>>>> leads in
>>>>> just single server in the configuration and no time 
>>>>> synchronization when
>>>>> this
>>>>> server is down/decommissioned.
>>>>>
>>>>> * ipa-client-install replaces the NTP configuration. If there was any
>>>>> parts
>>>>> previously edited by system administrator it's lost.
>>>>>
>>>>> * ipa-server-install adds {0-4}.$PLATFORM.pool.ntp.org to 
>>>>> /etc/ntp.conf.
>>>>> What's the point in doing that? These servers're already in the
>>>>> configuration
>>>>> file installed with ntp package.
>>>>>
>>>>> I have NTP-related WIP patches that solve some of the issues but in
>>>>> general I
>>>>> would prefer to remove the whole thing together with documenting 
>>>>> "Please
>>>>> make
>>>>> sure that time on all FreeIPA servers and clients is synchronized. On
>>>>> most
>>>>> distributions this was already done during system installation."
>>>>>
>>>>> Can we mark NTP options deprecated in 4.5 and remove them and stop
>>>>> touching
>>>>> any time syncing service in 4.6?
>>>>>
>>>>
>>>> Considering that default config is just fine for normal cases, and 
>>>> given
>>>> how
>>>> poorly integrated it is into FreeIPA, I agree with David. FreeIPA 
>>>> should
>>>> get
>>>> out of configuration management business.
>>>>
>>>
>>> +1
>>>
>>> -- 
>>> Jan Cholasta
>>>
>>>
>>> -- 
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>>>
>>
>>
>>
>
>