ipatests: fix race condition in finalizer of encrypted backup test

When using a fixture, we get a temporary directory created and then
removed by pytest. Pytest uses `shutil.rmtree` call which collects all
files in the directory being removed and then removes them one by one.
At the point of removal of our GNUPGHOME directory, gpg daemon is being
shut down and there might still be an agent UNIX domain socket. The
removal actually overlaps in time with shut down of the gpg daemon, thus
causing `shutil.rmtree()` to fail when an agent UNIX domain socket is
removed by the daemon.

Change the way how we run the gpg agent to use a temporary systemd
service. Stop the service in the finalizer method so that systemd would
send SIGTERM signal and the gpg agent would clean itself up.

Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Stanislav Levin <slev@altlinux.org>

ipatests/test_ipaserver/test_install/test_installutils.py

@@ -55,21 +55,26 @@ def gpgkey(request, tempdir):
         f.write("allow-preset-passphrase\n")
 
     # daemonize agent (detach from the console and run in the background)
-    subprocess.Popen(
-        [paths.GPG_AGENT, '--batch', '--daemon'],
-        env=env, stdout=devnull, stderr=devnull
+    subprocess.run(
+        [paths.SYSTEMD_RUN, '--service-type=forking',
+         '--setenv=GNUPGHOME={}'.format(gnupghome),
+         '--setenv=LC_ALL=C.UTF-8',
+         '--setenv=LANGUAGE=C',
+         '--unit=gpg-agent', paths.GPG_AGENT, '--daemon', '--batch'],
+        check=True,
+        env=env,
     )
 
     def fin():
+        subprocess.run(
+            [paths.SYSTEMCTL, 'stop', 'gpg-agent'],
+            check=True,
+            env=env,
+        )
         if orig_gnupghome is not None:
             os.environ['GNUPGHOME'] = orig_gnupghome
         else:
             os.environ.pop('GNUPGHOME', None)
-        subprocess.run(
-            [paths.GPG_CONF, '--kill', 'all'],
-            check=True,
-            env=env,
-        )
 
     request.addfinalizer(fin)