cc_grub_dpkg: determine idevs in more robust manner with grub-probe (#358)

Replace the hardcoded list of devices with a more robust way of determining
the device which grub is installed to.

We use grub-probe to fetch the underlying disk the /boot directory is
located on, and attempt to match the disk with its /dev/disk/by-id value.
If no such /dev/disk/by-id/ value exists, we fallback to the plain disk
name.

The changes are robust to unstable kernel device names and ordering, and use
/dev/disk/by-id values to populate grub-pc/install_devices where possible.

LP: #1877491

1 files changed, 176 insertions, 0 deletions

diff --git a/cloudinit/config/tests/test_grub_dpkg.py b/cloudinit/config/tests/test_grub_dpkg.py
new file mode 100644
index 00000000..01efa330
--- /dev/null
+++ b/cloudinit/config/tests/test_grub_dpkg.py
@@ -0,0 +1,176 @@
+# This file is part of cloud-init. See LICENSE file for license information.
+
+import pytest
+
+from unittest import mock
+from logging import Logger
+from cloudinit.util import ProcessExecutionError
+from cloudinit.config.cc_grub_dpkg import fetch_idevs, handle
+
+
+class TestFetchIdevs:
+    """Tests cc_grub_dpkg.fetch_idevs()"""
+
+    # Note: udevadm info returns devices in a large single line string
+    @pytest.mark.parametrize(
+        "grub_output,path_exists,expected_log_call,udevadm_output"
+        ",expected_idevs",
+        [
+            # Inside a container, grub not installed
+            (
+                ProcessExecutionError(reason=FileNotFoundError()),
+                False,
+                mock.call("'grub-probe' not found in $PATH"),
+                '',
+                '',
+            ),
+            # Inside a container, grub installed
+            (
+                ProcessExecutionError(stderr="failed to get canonical path"),
+                False,
+                mock.call("grub-probe 'failed to get canonical path'"),
+                '',
+                '',
+            ),
+            # KVM Instance
+            (
+                ['/dev/vda'],
+                True,
+                None,
+                (
+                    '/dev/disk/by-path/pci-0000:00:00.0 ',
+                    '/dev/disk/by-path/virtio-pci-0000:00:00.0 '
+                ),
+                '/dev/vda',
+            ),
+            # Xen Instance
+            (
+                ['/dev/xvda'],
+                True,
+                None,
+                '',
+                '/dev/xvda',
+            ),
+            # NVMe Hardware Instance
+            (
+                ['/dev/nvme1n1'],
+                True,
+                None,
+                (
+                    '/dev/disk/by-id/nvme-Company_hash000 ',
+                    '/dev/disk/by-id/nvme-nvme.000-000-000-000-000 ',
+                    '/dev/disk/by-path/pci-0000:00:00.0-nvme-0 '
+                ),
+                '/dev/disk/by-id/nvme-Company_hash000',
+            ),
+            # SCSI Hardware Instance
+            (
+                ['/dev/sda'],
+                True,
+                None,
+                (
+                    '/dev/disk/by-id/company-user-1 ',
+                    '/dev/disk/by-id/scsi-0Company_user-1 ',
+                    '/dev/disk/by-path/pci-0000:00:00.0-scsi-0:0:0:0 '
+                ),
+                '/dev/disk/by-id/company-user-1',
+            ),
+        ],
+    )
+    @mock.patch("cloudinit.config.cc_grub_dpkg.util.logexc")
+    @mock.patch("cloudinit.config.cc_grub_dpkg.os.path.exists")
+    @mock.patch("cloudinit.config.cc_grub_dpkg.util.subp")
+    def test_fetch_idevs(self, m_subp, m_exists, m_logexc, grub_output,
+                         path_exists, expected_log_call, udevadm_output,
+                         expected_idevs):
+        """Tests outputs from grub-probe and udevadm info against grub-dpkg"""
+        m_subp.side_effect = [
+            grub_output,
+            ["".join(udevadm_output)]
+        ]
+        m_exists.return_value = path_exists
+        log = mock.Mock(spec=Logger)
+        idevs = fetch_idevs(log)
+        assert expected_idevs == idevs
+        if expected_log_call is not None:
+            assert expected_log_call in log.debug.call_args_list
+
+
+class TestHandle:
+    """Tests cc_grub_dpkg.handle()"""
+
+    @pytest.mark.parametrize(
+        "cfg_idevs,cfg_idevs_empty,fetch_idevs_output,expected_log_output",
+        [
+            (
+                # No configuration
+                None,
+                None,
+                '/dev/disk/by-id/nvme-Company_hash000',
+                (
+                    "Setting grub debconf-set-selections with ",
+                    "'/dev/disk/by-id/nvme-Company_hash000','false'"
+                ),
+            ),
+            (
+                # idevs set, idevs_empty unset
+                '/dev/sda',
+                None,
+                '/dev/sda',
+                (
+                    "Setting grub debconf-set-selections with ",
+                    "'/dev/sda','false'"
+                ),
+            ),
+            (
+                # idevs unset, idevs_empty set
+                None,
+                'true',
+                '/dev/xvda',
+                (
+                    "Setting grub debconf-set-selections with ",
+                    "'/dev/xvda','true'"
+                ),
+            ),
+            (
+                # idevs set, idevs_empty set
+                '/dev/vda',
+                'false',
+                '/dev/disk/by-id/company-user-1',
+                (
+                    "Setting grub debconf-set-selections with ",
+                    "'/dev/vda','false'"
+                ),
+            ),
+            (
+                # idevs set, idevs_empty set
+                # Respect what the user defines, even if its logically wrong
+                '/dev/nvme0n1',
+                'true',
+                '',
+                (
+                    "Setting grub debconf-set-selections with ",
+                    "'/dev/nvme0n1','true'"
+                ),
+            )
+        ],
+    )
+    @mock.patch("cloudinit.config.cc_grub_dpkg.fetch_idevs")
+    @mock.patch("cloudinit.config.cc_grub_dpkg.util.get_cfg_option_str")
+    @mock.patch("cloudinit.config.cc_grub_dpkg.util.logexc")
+    @mock.patch("cloudinit.config.cc_grub_dpkg.util.subp")
+    def test_handle(self, m_subp, m_logexc, m_get_cfg_str, m_fetch_idevs,
+                    cfg_idevs, cfg_idevs_empty, fetch_idevs_output,
+                    expected_log_output):
+        """Test setting of correct debconf database entries"""
+        m_get_cfg_str.side_effect = [
+            cfg_idevs,
+            cfg_idevs_empty
+        ]
+        m_fetch_idevs.return_value = fetch_idevs_output
+        log = mock.Mock(spec=Logger)
+        handle(mock.Mock(), mock.Mock(), mock.Mock(), log, mock.Mock())
+        log.debug.assert_called_with("".join(expected_log_output))
+
+
+# vi: ts=4 expandtab