Bug 1372457, explained the impact of disabling dnsmasq

[ahardin-rh]

https://bugzilla.redhat.com/show_bug.cgi?id=1372457

and

https://bugzilla.redhat.com/show_bug.cgi?id=1372456

[ahardin-rh]

@miheer @sferich888 PTAL. Thanks!

[ahardin-rh]

Approved by QE.

@miheer @sferich888 PTAL
@adellape @bfallonf @tpoitras peer review please 🙇

[sferich888]

@rjhowe PTAL

[bfallonf]

@ahardin-rh I think I'm a little confused by the above. Should it say:

"If you want to set up X, then set openshift_use_dnsmasq in the Ansible playbook to false."

or

"If you set up X, then {product-title} sets openshift_use_dnsmasq in the Ansible playbook to false"

?

[ahardin-rh]

Fixed. Thanks!

[bfallonf]

@ahardin-rh Would it be worth suggesting that the entire addition here be included in a Warning box or something? The previous procedure seems to use dnsmasq, so it's a bit jarring seeing this topic as a new section.

Otherwise, LGTM!

[ahardin-rh]

@bfallonf Thanks! I think it's a lot of information to place in a warning box, so I made it its own true section.

[rjhowe]

I do not understand this statement, are we talking about the route exposed for the registry or the SKYDNS service name. Even with out dnsmasq we should be able to use both if the cluster is configured correctly. We inject the kubernetes service ip and search domains in the container resolv.conf and take resolv.conf from the host. So we should be able to resolve everything still.

Unless things have changed in later versions.

[ahardin-rh]

@rjhowe Thanks. I removed the statement.

[ahardin-rh]

[rev_history]
|xref:../install_config/install/prerequisites.adoc#install-config-install-prerequisites[Installing -> Prerequisites]
|Added information about xref:../install_config/install/prerequisites.adoc#dns-config-prereq-disabling-dnsmasq[disabling dnsmasq].
%