add 'systemctl' command and use it in postinstall

The 'systemctl' command can be used to enable, disable, or mask systemd
units inside the runtime being modified. Modify runtime-postinstall.tmpl
to use the 'systemctl' command.

We also no longer remove quota*.service or kexec*.service, since
these aren't enabled by default. And systemd-remount-api-vfs.service
should work correctly now, so we can leave it alone as well.

share/runtime-postinstall.tmpl

@@ -20,18 +20,24 @@ move etc/yum.repos.d etc/anaconda.repos.d
 
 ## Configure systemd to start anaconda
 remove etc/systemd/system/default.target
-remove etc/systemd/system/default.target.wants/*
 symlink /lib/systemd/system/anaconda.target etc/systemd/system/default.target
-## remove/disable unwanted systemd services
-removefrom systemd /usr/lib/systemd/system/kexec*
-removefrom systemd /usr/lib/systemd/system/local-fs.target.wants/media.mount
-removefrom systemd /usr/lib/systemd/system/media.mount
-removefrom systemd /usr/lib/systemd/system/*plymouth*
-removefrom systemd /usr/lib/systemd/system/quota*.service
-removefrom systemd /usr/lib/systemd/system/systemd-remount-api-vfs.service
-removefrom initscripts */lib/systemd/system/local-fs.target.wants/fedora-storage*.service */lib/systemd/system/basic.target.wants/*.service
-removefrom lvm2 */lib/systemd/system/*
-removefrom mdadm */lib/systemd/system/*
+
+## Disable unwanted systemd services
+systemctl disable systemd-readahead-collect.service \
+                  systemd-readahead-replay.service \
+                  mdmonitor.service \
+                  mdmonitor-takeover.service \
+                  lvm2-monitor.service
+## These services can't be disabled normally (they're linked into place in
+## /usr/lib/systemd rather than /etc/systemd), so we have to mask them.
+systemctl mask fedora-configure.service fedora-loadmodules.service \
+               fedora-storage-init.service fedora-storage-init-late.service \
+               fedora-autorelabel.service fedora-autorelabel-mark.service \
+               fedora-wait-storage.service media.mount \
+               plymouth-quit.service plymouth-quit-wait.service \
+               plymouth-kexec.service plymouth-halt.service \
+               plymouth-poweroff.service plymouth-reboot.service \
+               plymouth-read-write.service plymouth-start.service
 
 ## install some basic configuration files
 append etc/resolv.conf ""

src/pylorax/ltmpl.py

@@ -531,3 +531,25 @@ class LoraxTemplateRunner(object):
         addrsize_data = struct.pack(">iiii", 0, int(addr, 16), 0, os.stat(src).st_size)
         addrsize.write(addrsize_data)
         addrsize.close()
+
+    def systemctl(self, cmd, *units):
+        '''
+        systemctl [enable|disable|mask] UNIT [UNIT...]
+          Enable, disable, or mask the given systemd units.
+          Examples:
+            systemctl disable lvm2-monitor.service
+            systemctl mask fedora-storage-init.service fedora-configure.service
+        '''
+        if cmd not in ('enable', 'disable', 'mask'):
+            raise ValueError('unsupported systemctl cmd: %s' % cmd)
+        if not units:
+            logger.debug("systemctl: no units given for %s, ignoring", cmd)
+            return
+        self.mkdir("/run/systemd/system") # XXX workaround for systemctl bug
+        systemctl = ('systemctl', '--root', self.outroot, '--no-reload',
+                     '--quiet', cmd)
+        # XXX for some reason 'systemctl enable/disable' always returns 1
+        try:
+            check_call(systemctl + units)
+        except CalledProcessError:
+            pass