I'm looking for the best approach to take for configuring IdM clients to
access web services (HTTP)
with keytabs when a front-end load-balanced hostname is in place.
I have a distributed OpenShift Enterprise configuration with three
broker hosts (broker1, broker2, broker3)
with all three configured as IdM clients.
IdM is configured with one server (idm-srv1.example.com), one replica
(idm-srv2.example.com); an HTTP service
has been created for each broker host:
# ipa service-add HTTP/broker1.example.com
# ipa service-add HTTP/broker2.example.com
# ipa service-add HTTP/broker3.example.com
A DNS round-robin hostname called '*broker**.example.com*' has also been
configured to distribute broker requests
across the three brokers:
# ipa dnsrecord-add example.com broker --a-ip-address=10.0.0.11
# ipa dnsrecord-add example.com broker --a-ip-address=10.0.0.12
# ipa dnsrecord-add example.com broker --a-ip-address=10.0.0.13
Effectively, this creates a DNS A record that acts as a pseudo DNS
To access the HTTP services, we have been creating keytabs for for the
first broker host:
# ipa-getkeytab -s idm-srv1.example.com -p
and copying the keytab over to the other two OpenShift broker hosts.
This all works fine but in the event that *broker1* should go down, the
other broker hosts will lose access
to the web service. Ideally, we would like to have web services use the
more generic, "load balanced"
hostname (*broker.example.com*) and in turn have the keytabs use this
name as well.
I tried creating an HTTP service using the "load balanced" hostname
(*broker.example.com*) but that appears to fail
due to *broker.example.com* not being a valid host within IdM:
# ipa service-add HTTP/broker.example.com
ipa: ERROR: The host 'broker.example.com' does not exist to add a
In the F18 FreeIPA guide it discusses creating a combined keytab file
(Section 6.5.4) using ktutil:
but would that still work as intended should a broker host go down?
The next section (6.5.5) mentions creating a keytab to create a service
principal that can be used across multiple hosts:
# ipa-getkeytab -s kdc.example.com -p HTTP/server.example.com -k
/etc/httpd/conf/krb5.keytab -e des-cbc-crc
Which seems more in-line with my thinking and exactly what we've been
doing but again, if I try to do that
using the "load balanced" hostname (*broker.example.com*) it fails sicne
it's not a valid host within IdM.
What is the best method to doing this?
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