[Freeipa-devel] How to support Designate?

[Petr Spacek]

On 26.8.2015 20:09, Rich Megginson wrote:
> On 08/25/2015 09:08 AM, Petr Spacek wrote:
>> On 8.7.2015 19:56, Rich Megginson wrote:
>>> On 07/08/2015 10:11 AM, Petr Spacek wrote:
>>>> Assuming that Designate wants to own DNS and be Primary Master, it would be
>>>> awesome if they could support standard DNS UPDATE protocol (RFC 2136)
>>>> alongside their own JSON API.
>>>>
>>>> The JSON API is superset of DNS UPDATE protocol because it allows to add
>>>> zones
>>>> but still, standard protocol would mean that standard client (possibly guest
>>>> OS inside VM) can update its records without any OpenStack dependency, which
>>>> is very much desirable.
>>>>
>>>> The use case here is to allow the guest OS to publish it's SSH key (which was
>>>> generated inside the VM after first boot) to prevent Man in the middle
>>>> attacks.
> 
> I'm working on a different approach for guest OS registration.  This involves
> a Nova hook/plugin:
> * build_instance pre-hook to generate an OTP and call ipa host-add with the
> OTP - add OTP to new host metadata - add ipa-client-registration script to new
> host cloud-init
> * new instance calls script - will wait for OTP to become available in
> metadata, then call ipa-client-install with OTP
> * Floating IP is assigned to VM - Nova hook will call dnsrecord-add with new IP

BTW dnsrecord-add can be omitted if standard DNS UPDATE is supported.
ipa-client-install is using DNS UPDATE today.

> https://github.com/richm/rdo-vm-factory/tree/master/rdo-ipa-nova
> 
>>>> The same goes for all other sorts of DANE/DNSSEC data or service
>>>> discovery using DNS, where a guest/container running a distributed service
>>>> can
>>>> publish it's existence in DNS.
>>>>
>>>> DNS UPDATE supports GSS(API) for authentication via RFC 3007 and that is
>>>> widely supported, too.
>>>>
>>>> So DNS UPDATE is my biggest wish :-)
>>>>
>>> Ok.  There was a Designate blueprint for such a feature, but I can't find it
>>> and neither can the Designate guys.  There is a mention of nsupdate in the
>>> minidns blueprint, but that's about it.  The fact that Designate upstream
>>> can't find the bp suggests that this is not a high priority for them and will
>>> not likely implement it on their own i.e. we would have to contribute this
>>> feature.
>>>
>>> If Designate had such a feature, how would this help us integrate FreeIPA with
>>> Designate?
>> It would greatly simplify integration with FreeIPA. There is a plan to support
>> DNS updates as described in RFC 2136 to push updates from FreeIPA servers to
>> external DNS servers, so we could use the same code to integrate with AD &
>> Designate at the same time.
>>
>> (I'm sorry for the delay, it somehow slipped through the cracks.)
>>
> 
> For Designate for our use cases, we want IPA to be the authoritative source of
> DNS data.

Why? In my eyes it is additional complexity for no obvious benefit. DNS is
built around assumption that there is only one authoritative source of data
and as far as I can tell all attempts to bend this assumption did not end well.

In my eyes IPA should have ability to integrate with whatever DNS server admin
wants to use, using standard protocols.

What is the benefit of the other approach?

Petr^2 Spacek


> When a client wants to read data from Designate, that data should somehow come
> from IPA.  I don't think Designate has any sort of proxy or pass-through
> feature, so the data would have be sync'd from IPA.  If IPA supports being a
> server for AXFR/IXFR, Designate could be changed to support AXFR/IXFR client
> side, then would just be a slave of IPA.  If IPA does not support zone
> transfers, then we would need some sort of initial sync of data from IPA to
> Designate (I wrote such a script for Designate
> (https://github.com/openstack/designate/blob/master/contrib/ipaextractor.py).
> Then, perhaps some sort of proxy/service that would poll for changes
> (syncrepl?) in IPA, then submit those changes to Designate (using Designate
> REST API, or DNS UPDATE when Designate mDNS supports it).
> 
> When a client wants to update data in Designate, we need to somehow get that
> data into IPA.  The only way Designate pushes data out currently is via AXFR,
> which doesn't work for IPA to be a direct slave of Designate.  What might work
> is to have an "agent" that gets the AXFR, then somehow converts that into IPA
> updates.   This would only work if the volume of updates is fairly low.  If
> Designate supported IXFR it would be much better.