podman: stop the docker container during upgrade

When deploying Podman containers, we want to make sure the container
that was running in Docker has been stopped.
That's part of the upgrade process, where later, we'll remove the
container in THT / upgrade_tasks.

Change-Id: I6831b4b952c95fde31febf8e14cb27cf22ff859b

paunch/builder/base.py

@@ -11,8 +11,10 @@
 #   under the License.
 #
 
+import distutils.spawn
 import json
 import re
+import shutil
 import tenacity
 
 from paunch.utils import common
@@ -57,6 +59,13 @@ class BaseBuilder(object):
                                and action == 'run')
             start_cmd = 'create' if systemd_managed else 'run'
 
+            # When upgrading from Docker to Podman, we want to stop the
+            # container that runs under Docker first before starting it with
+            # Podman. The container will be removed later in THT during
+            # upgrade_tasks.
+            if self.runner.cont_cmd == 'podman' and self.which('docker'):
+                self.runner.stop_container(container, 'docker')
+
             if action == 'run':
                 if container in desired_names:
                     self.log.debug('Skipping existing container: %s' %
@@ -251,6 +260,13 @@ class BaseBuilder(object):
     def lower(self, a):
         return str(a).lower()
 
+    def which(self, program):
+        try:
+            pgm = shutil.which(program)
+        except AttributeError:
+            pgm = distutils.spawn.find_executable(program)
+        return pgm
+
     def duration(self, a):
         if isinstance(a, (int, float)):
             return a

paunch/runner.py

@@ -169,6 +169,14 @@ class BaseRunner(object):
             self.log.error('Error removing container: %s' % container)
             self.log.error(cmd_stderr)
 
+    def stop_container(self, container, cont_cmd=None):
+        cont_cmd = cont_cmd or self.cont_cmd
+        cmd = [cont_cmd, 'stop', container]
+        cmd_stdout, cmd_stderr, returncode = self.execute(cmd)
+        if returncode != 0:
+            self.log.error('Error stopping container: %s' % container)
+            self.log.error(cmd_stderr)
+
     def rename_containers(self):
         current_containers = []
         need_renaming = {}

paunch/tests/test_runner.py

@@ -212,6 +212,24 @@ class TestBaseRunner(base.TestCase):
             popen, ['docker', 'rm', '-f', 'one']
         )
 
+    @mock.patch('subprocess.Popen')
+    def test_stop_container(self, popen):
+        self.mock_execute(popen, '', '', 0)
+
+        self.runner.stop_container('one')
+        self.assert_execute(
+            popen, ['docker', 'stop', 'one']
+        )
+
+    @mock.patch('subprocess.Popen')
+    def test_stop_container_override(self, popen):
+        self.mock_execute(popen, '', '', 0)
+
+        self.runner.stop_container('one', 'podman')
+        self.assert_execute(
+            popen, ['podman', 'stop', 'one']
+        )
+
     @mock.patch('subprocess.Popen')
     def test_container_names(self, popen):
         ps_result = '''one one