sahara-image-pack: RHEL-based images can not be generated with various plugins

[Luigi Toscano]

The various plugins for Plugin-Declared Image Generation have some trouble with RHEL-based images. Few issues identified so far:

* 'rhel': 'redhat' should be added to _DISTRO_FAMILES in sahara/plugins/images.py; libguestfs identifies RHEL with 'rhel', and otherwise the process bails out;
* few conditionals in the declarative definition of image check/build contains:
  - os_case:
     - centos:

but that should really be 'redhat:' instead, which encompasses both centos and RHEL.

Even when enabling those, there are probably other issues; for example, when generating a MapR image on RHEL, even with the fixes above applied, the process ends with:

[...]
2018-03-06 19:51:34.088 13863 INFO sahara.cli.image_pack.cli [-] Issuing command: rpm -q cups cdparanoia-libs cups-libs createrepo cvs cyrus-sasl-gssapi cyrus-sasl-plain foomatic foomatic-db foomatic-db-f[25/1996]
 foomatic-db-ppds gdbm-devel gettext ghostscript ghostscript-fonts glibc glibc-common glibc-devel glibc-headers gstreamer gstreamer-plugins-base gstreamer-tools hdparm irqbalance iso-codes kernel-headers libXt lib
Xv libXxf86vm libgomp libgudev1 libicu libmng liboil libtheora libtirpc libvisual libxslt mesa-dri-drivers mesa-libGL mesa-libGLU mesa-private-llvm nmap-ncat numactl openjpeg-libs patch pax perl-CGI perl-ExtUtils-
MakeMaker perl-ExtUtils-ParseXS perl-Test-Harness perl-Test-Simple perl-devel phonon-backend-gstreamer poppler poppler-data poppler-utils portreserve qt qt-x11 qt3 redhat-lsb redhat-lsb-core redhat-lsb-printing ur
w-fonts yum-utils xml-common
2018-03-06 19:51:44.297 13863 CRITICAL sahara [-] Unhandled error: RuntimeError: sh:
2018-03-06 19:51:44.297 13863 ERROR sahara Traceback (most recent call last):
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/bin/sahara-image-pack", line 10, in <module>
2018-03-06 19:51:44.297 13863 ERROR sahara sys.exit(main())
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/cli/image_pack/cli.py", line 121, in main
2018-03-06 19:51:44.297 13863 ERROR sahara CONF.root_fs, CONF.test_only)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/cli/image_pack/api.py", line 127, in pack_image
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/mapr/plugin.py", line 108, in pack_image
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/mapr/base/base_version_handler.py", line 193, in pack_image
2018-03-06 19:51:44.297 13863 ERROR sahara remote, test_only=test_only, image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/mapr/images.py", line 31, in pack_image
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 52, in handler
2018-03-06 19:51:44.297 13863 ERROR sahara func(*args, **kwargs)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 411, in validate
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=argument_values)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 892, in validate
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 966, in validate
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 892, in validate
2018-03-06 19:51:44.297 13863 ERROR sahara image_arguments=image_arguments)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 52, in handler
2018-03-06 19:51:44.297 13863 ERROR sahara func(*args, **kwargs)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 532, in validate
2018-03-06 19:51:44.297 13863 ERROR sahara check(self, remote)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 544, in _rpm_check
2018-03-06 19:51:44.297 13863 ERROR sahara return _sudo(remote, check_cmd)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/plugins/images.py", line 1111, in _sudo
2018-03-06 19:51:44.297 13863 ERROR sahara return remote.execute_command(cmd, run_as_root=True, **kwargs)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib/python2.7/site-packages/sahara/cli/image_pack/api.py", line 92, in execute_command
2018-03-06 19:51:44.297 13863 ERROR sahara stdout = self.guest.sh(cmd)
2018-03-06 19:51:44.297 13863 ERROR sahara File "/usr/lib64/python2.7/site-packages/guestfs.py", line 9470, in sh
2018-03-06 19:51:44.297 13863 ERROR sahara r = libguestfsmod.sh(self._o, command)
2018-03-06 19:51:44.297 13863 ERROR sahara RuntimeError: sh:
2018-03-06 19:51:44.297 13863 ERROR sahara

Tested with the last version of sahara-image-pack from the Queens branch, using:

sahara-image-pack --image sahara-rhel7-mapr-5.2.0.qcow2 mapr 5.2.0.mrv2

sahara-rhel7-mapr-5.2.0.qcow2 is a RHEL 7.4 guest image (-191).

(originally reported as https://bugzilla.redhat.com/show_bug.cgi?id=1552596, but it can be fixed for everyone here).