[Freeipa-devel] [PATCH] 888 always verify hostname

[Martin Kosek]

On Thu, 2011-10-06 at 22:59 -0400, Rob Crittenden wrote:
> When installing with DNS we skip a few hostname checks on the assumption 
> that the DNS we are installing will cover things. We still need to 
> verify /etc/hosts and we do this with gethostbyname_ex() which returns 
> the primary name and all other names of the host. If the primary name 
> doesn't match (e.g. the shortname is defined first in /etc/hosts) or it 
> isn't resolvable at all then we error out.
> 
> This also prevents a chicken-and-egg error as several services need to 
> start before DNS is available so the hostname must be defined.
> 
> rob

I see several problems with the patch. At first, it needs a rebase, I
reworked the exceptions raised in verify_fqdn in #1899.

Then, this patch would break several things:

1) Now, when we install a server with --setup-dns and the host is not
resolvable, we add a record to /etc/hosts ourselves, so that the user is
not obliged to hack /etc/hosts:

# ipa-server-install --setup-dns
...
Server host name [vm-050.idm.lab.bos.redhat.com]: 

Warning: skipping DNS resolution of host vm-050.idm.lab.bos.redhat.com
The domain name has been calculated based on the host name.

Please confirm the domain name [idm.lab.bos.redhat.com]: 

Unable to resolve IP address for host name
Please provide the IP address to be used for this host name: 10.16.78.50
Adding [10.16.78.50 vm-050.idm.lab.bos.redhat.com] to your /etc/hosts file   <<<<<<
The IPA Master Server will be configured with
Hostname:    vm-050.idm.lab.bos.redhat.com
IP address:  10.16.78.50
Domain name: idm.lab.bos.redhat.com


2) This will break ipa-replica-prepare. We cannot assume that only local
host names are passed to to verify_fqdn since it is also used to for new
replica hostname check in ipa-replica-prepare:

# ipa-replica-prepare vm-103.idm.lab.bos.redhat.com
Directory Manager (existing master) password: 

The host name vm-103.idm.lab.bos.redhat.com is not resolvable. It must
appear in at least /etc/hosts.
Add the --ip-address argument to create a DNS entry.

We must be very cautious in this function, there was already a BZ from
RHEV-M guys which could be now broken:

https://bugzilla.redhat.com/show_bug.cgi?id=729357

Martin