Wait for apt lock (#1034)

Currently any attempt to run an apt command while another process holds
an apt lock will fail. We should instead wait to acquire the apt lock.

LP: #1944611

2 files changed, 81 insertions, 3 deletions

diff --git a/tests/unittests/test_distros/test_debian.py b/tests/unittests/test_distros/test_debian.py
index 7ff8240b..a88c2686 100644
--- a/tests/unittests/test_distros/test_debian.py
+++ b/tests/unittests/test_distros/test_debian.py
@@ -1,8 +1,16 @@
 # This file is part of cloud-init. See LICENSE file for license information.
+from itertools import count, cycle
+from unittest import mock
 
-from cloudinit import distros
-from cloudinit import util
-from cloudinit.tests.helpers import (FilesystemMockingTestCase, mock)
+import pytest
+
+from cloudinit import distros, util
+from cloudinit.distros.debian import (
+    APT_GET_COMMAND,
+    APT_GET_WRAPPER,
+)
+from cloudinit.tests.helpers import FilesystemMockingTestCase
+from cloudinit import subp
 
 
 @mock.patch("cloudinit.distros.debian.subp.subp")
@@ -98,3 +106,69 @@ class TestDebianApplyLocale(FilesystemMockingTestCase):
             m_subp.assert_not_called()
         self.assertEqual(
             'Failed to provide locale value.', str(ctext_m.exception))
+
+
+@mock.patch.dict('os.environ', {}, clear=True)
+@mock.patch("cloudinit.distros.debian.subp.which", return_value=True)
+@mock.patch("cloudinit.distros.debian.subp.subp")
+class TestPackageCommand:
+    distro = distros.fetch("debian")("debian", {}, None)
+
+    @mock.patch("cloudinit.distros.debian.Distro._apt_lock_available",
+                return_value=True)
+    def test_simple_command(self, m_apt_avail, m_subp, m_which):
+        self.distro.package_command('update')
+        apt_args = [APT_GET_WRAPPER['command']]
+        apt_args.extend(APT_GET_COMMAND)
+        apt_args.append('update')
+        expected_call = {
+            'args': apt_args,
+            'capture': False,
+            'env': {'DEBIAN_FRONTEND': 'noninteractive'},
+        }
+        assert m_subp.call_args == mock.call(**expected_call)
+
+    @mock.patch("cloudinit.distros.debian.Distro._apt_lock_available",
+                side_effect=[False, False, True])
+    @mock.patch("cloudinit.distros.debian.time.sleep")
+    def test_wait_for_lock(self, m_sleep, m_apt_avail, m_subp, m_which):
+        self.distro._wait_for_apt_command("stub", {"args": "stub2"})
+        assert m_sleep.call_args_list == [mock.call(1), mock.call(1)]
+        assert m_subp.call_args_list == [mock.call(args='stub2')]
+
+    @mock.patch("cloudinit.distros.debian.Distro._apt_lock_available",
+                return_value=False)
+    @mock.patch("cloudinit.distros.debian.time.sleep")
+    @mock.patch("cloudinit.distros.debian.time.time", side_effect=count())
+    def test_lock_wait_timeout(
+        self, m_time, m_sleep, m_apt_avail, m_subp, m_which
+    ):
+        with pytest.raises(TimeoutError):
+            self.distro._wait_for_apt_command("stub", "stub2", timeout=5)
+        assert m_subp.call_args_list == []
+
+    @mock.patch("cloudinit.distros.debian.Distro._apt_lock_available",
+                side_effect=cycle([True, False]))
+    @mock.patch("cloudinit.distros.debian.time.sleep")
+    def test_lock_exception_wait(self, m_sleep, m_apt_avail, m_subp, m_which):
+        exception = subp.ProcessExecutionError(
+            exit_code=100, stderr="Could not get apt lock"
+        )
+        m_subp.side_effect = [exception, exception, "return_thing"]
+        ret = self.distro._wait_for_apt_command("stub", {"args": "stub2"})
+        assert ret == "return_thing"
+
+    @mock.patch("cloudinit.distros.debian.Distro._apt_lock_available",
+                side_effect=cycle([True, False]))
+    @mock.patch("cloudinit.distros.debian.time.sleep")
+    @mock.patch("cloudinit.distros.debian.time.time", side_effect=count())
+    def test_lock_exception_timeout(
+        self, m_time, m_sleep, m_apt_avail, m_subp, m_which
+    ):
+        m_subp.side_effect = subp.ProcessExecutionError(
+            exit_code=100, stderr="Could not get apt lock"
+        )
+        with pytest.raises(TimeoutError):
+            self.distro._wait_for_apt_command(
+                "stub", {"args": "stub2"}, timeout=5
+            )
diff --git a/tests/unittests/test_handler/test_handler_landscape.py b/tests/unittests/test_handler/test_handler_landscape.py
index 00333985..1cc73ea2 100644
--- a/tests/unittests/test_handler/test_handler_landscape.py
+++ b/tests/unittests/test_handler/test_handler_landscape.py
@@ -22,6 +22,10 @@ class TestLandscape(FilesystemMockingTestCase):
         self.conf = self.tmp_path('client.conf', self.new_root)
         self.default_file = self.tmp_path('default_landscape', self.new_root)
         self.patchUtils(self.new_root)
+        self.add_patch(
+            'cloudinit.distros.ubuntu.Distro.install_packages',
+            'm_install_packages'
+        )
 
     def test_handler_skips_empty_landscape_cloudconfig(self):
         """Empty landscape cloud-config section does no work."""