MAAS deployment of Ubuntu 17.04 fails with custom preseed

[Rod Smith]

Deployment of Ubuntu 17.04 beta via MAAS with the custom preseed fails because of a dependency on postfix that seems to have crept in somewhere. The postfix package requires manual configuration, which causes the automated MAAS deployment to fail.

Upon deploying with the standard preseed, I'm able to install canonical-certification-checkbox and configure postfix as part of that installation. Removing postfix also requires removing mailutils, but nothing else, but I see no mention of mailutils in Checkbox dependencies, so I'm not sure why this particular dependency mess is occurring.

Output from the MAAS deployment logs includes the following:

Preparing to unpack .../221-postfix_3.1.4-4_amd64.deb ...
(B)0






















Package configurationlqqqqqqqqqqqqqqqqqqqqqqqqu Postfix Configuration tqqqqqqqqqqqqqqqqqqqqqqqqkx x x Please select the mail server configuration type that best meets your  x needs.  x   x  No configuration:  x  Should be chosen to leave the current configuration unchanged.  x  Internet site:  x  Mail is sent and received directly using SMTP.  x  Internet with smarthost:  x  Mail is received directly using SMTP or by running a utility such  x  as fetchmail. Outgoing mail is sent using a smarthost.  x  Satellite system:  x  All mail is sent to another machine, called a 'smarthost', for  x delivery.  x  Local only:  x  The only delivered mail is the mail for local users. There is no  x  x <Ok>  x x mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj  [?25h[?0c

Failed to open terminal.debconf: whiptail output the above errors, giving up!
Use of uninitialized value $ret in scalar chomp at /usr/share/perl5/Debconf/Client/ConfModule.pm line 132, <STDIN> line 5.
Use of uninitialized value $ret in split at /usr/share/perl5/Debconf/Client/ConfModule.pm line 133, <STDIN> line 5.
Use of uninitialized value $ret[0] in string eq at /usr/share/perl5/Debconf/Client/ConfModule.pm line 134, <STDIN> line 5.
dpkg: error processing archive /tmp/apt-dpkg-install-rv18sv/221-postfix_3.1.4-4_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 25

Later in the logs, this appears:

Errors were encountered while processing:
 /tmp/apt-dpkg-install-rv18sv/221-postfix_3.1.4-4_amd64.deb
W: --force-yes is deprecated, use one of the options starting with --allow instead.
W: --force-yes is deprecated, use one of the options starting with --allow instead.
E: Sub-process /usr/bin/dpkg returned an error code (1)

[Rod Smith (rodsmith)]

A second issue is the secureid sub-script in the preseed file, which seems to be keeping something in /dev open for too long. Adding a 5-second pause to the end of the secureid sub-script fixes this problem.