FreeBSD: Make freebsd a variant, fix unittests and tools/build-on-freebsd.

 - Simplify the logic of 'variant' in util.system_info
   much of the data from
   https://github.com/hpcugent/easybuild/wiki/OS_flavor_name_version
 - fix get_resource_disk_on_freebsd when running on a system without
   an Azure resource disk.
 - fix tools/build-on-freebsd to replace oauth with oauthlib and add
   bash which is a dependency for tests.
 - update a fiew places that were checking for freebsd but not using
   the util.is_FreeBSD()

2 files changed, 7 insertions, 4 deletions

diff --git a/tests/unittests/test_handler/test_handler_ntp.py b/tests/unittests/test_handler/test_handler_ntp.py
index c4299d94..7f278646 100644
--- a/tests/unittests/test_handler/test_handler_ntp.py
+++ b/tests/unittests/test_handler/test_handler_ntp.py
@@ -62,7 +62,7 @@ class TestNtp(FilesystemMockingTestCase):
     def test_ntp_rename_ntp_conf(self):
         """When NTP_CONF exists, rename_ntp moves it."""
         ntpconf = self.tmp_path("ntp.conf", self.new_root)
-        os.mknod(ntpconf)
+        util.write_file(ntpconf, "")
         with mock.patch("cloudinit.config.cc_ntp.NTP_CONF", ntpconf):
             cc_ntp.rename_ntp_conf()
         self.assertFalse(os.path.exists(ntpconf))
diff --git a/tests/unittests/test_util.py b/tests/unittests/test_util.py
index 014aa6a3..a73fd26a 100644
--- a/tests/unittests/test_util.py
+++ b/tests/unittests/test_util.py
@@ -20,6 +20,9 @@ except ImportError:
     import mock
 
 
+BASH = util.which('bash')
+
+
 class FakeSelinux(object):
 
     def __init__(self, match_what):
@@ -544,17 +547,17 @@ class TestReadSeeded(helpers.TestCase):
 
 class TestSubp(helpers.TestCase):
 
-    stdin2err = ['bash', '-c', 'cat >&2']
+    stdin2err = [BASH, '-c', 'cat >&2']
     stdin2out = ['cat']
     utf8_invalid = b'ab\xaadef'
     utf8_valid = b'start \xc3\xa9 end'
     utf8_valid_2 = b'd\xc3\xa9j\xc8\xa7'
-    printenv = ['bash', '-c', 'for n in "$@"; do echo "$n=${!n}"; done', '--']
+    printenv = [BASH, '-c', 'for n in "$@"; do echo "$n=${!n}"; done', '--']
 
     def printf_cmd(self, *args):
         # bash's printf supports \xaa.  So does /usr/bin/printf
         # but by using bash, we remove dependency on another program.
-        return(['bash', '-c', 'printf "$@"', 'printf'] + list(args))
+        return([BASH, '-c', 'printf "$@"', 'printf'] + list(args))
 
     def test_subp_handles_utf8(self):
         # The given bytes contain utf-8 accented characters as seen in e.g.