fix(sources/wsl): no error with empty .cloud-init dir (SC-1862) (#5633)

Do not treat the emptiness of .cloud-init/ as an error in the logs
if agent.yaml is present.

Fixes GH-5632

cloudinit/sources/DataSourceWSL.py

@@ -405,7 +405,8 @@ def _get_data(self) -> bool:
                 user_data = ConfigData(self.find_user_data_file(seed_dir))
 
         except (ValueError, IOError) as err:
-            LOG.error(
+            log = LOG.info if agent_data else LOG.error
+            log(
                 "Unable to load any user-data file in %s: %s",
                 seed_dir,
                 str(err),

doc/rtd/reference/datasources/wsl.rst

@@ -52,6 +52,8 @@ User data can be supplied in any
 cloud-config files or shell scripts. At runtime, the WSL datasource looks for
 user data in the following locations inside the Windows host filesystem, in the
 order specified below.
+The WSL datasource will be enabled if cloud-init discovers at least one of the
+applicable config files described below.
 
 First, configurations from Ubuntu Pro/Landscape are checked for in the
 following paths:
@@ -71,8 +73,8 @@ following paths:
    used instead of the one provided by the ``agent.yaml``, which is treated as
    a default.
 
-Then, if a file from (1) is not found, a user-provided configuration will be
-looked for instead in the following order:
+Then, if a file from (1) is not found, optional user-provided configuration
+will be looked for in the following order:
 
 1. ``%USERPROFILE%\.cloud-init\<InstanceName>.user-data`` holds user data for a
    specific instance configuration. The datasource resolves the name attributed

tests/unittests/sources/test_wsl.py

@@ -5,6 +5,7 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 import logging
 import os
+import re
 from copy import deepcopy
 from email.mime.multipart import MIMEMultipart
 from pathlib import PurePath
@@ -460,6 +461,52 @@ def test_get_data_jinja(self, m_lsb_release, paths, tmpdir):
             cast(MIMEMultipart, ud), "text/cloud-config"
         ), "No cloud-config part should exist"
 
+    @pytest.mark.parametrize("with_agent_data", [True, False])
+    @mock.patch("cloudinit.util.lsb_release")
+    def test_get_data_x(
+        self, m_lsb_release, with_agent_data, caplog, paths, tmpdir
+    ):
+        """
+        Assert behavior of empty .cloud-config dir with and without agent data
+        """
+        m_lsb_release.return_value = SAMPLE_LINUX_DISTRO
+        data_path = tmpdir.join(".cloud-init", f"{INSTANCE_NAME}.user-data")
+        data_path.dirpath().mkdir()
+
+        if with_agent_data:
+            ubuntu_pro_tmp = tmpdir.join(".ubuntupro", ".cloud-init")
+            os.makedirs(ubuntu_pro_tmp, exist_ok=True)
+            agent_path = ubuntu_pro_tmp.join("agent.yaml")
+            agent_path.write(AGENT_SAMPLE)
+
+        ds = wsl.DataSourceWSL(
+            sys_cfg=SAMPLE_CFG,
+            distro=_get_distro("ubuntu"),
+            paths=paths,
+        )
+
+        assert ds.get_data() is with_agent_data
+        if with_agent_data:
+            assert ds.userdata_raw == AGENT_SAMPLE
+        else:
+            assert ds.userdata_raw is None
+
+        expected_log_level = logging.INFO if with_agent_data else logging.ERROR
+        regex = (
+            "Unable to load any user-data file in /[^:]*/.cloud-init:"
+            " /.*/.cloud-init directory is empty"
+        )
+        messages = [
+            x.message
+            for x in caplog.records
+            if x.levelno == expected_log_level and re.match(regex, x.message)
+        ]
+        assert (
+            len(messages) > 0
+        ), "Expected log message matching '{}' with log level '{}'".format(
+            regex, expected_log_level
+        )
+
     @mock.patch("cloudinit.util.get_linux_distro")
     def test_data_precedence(self, m_get_linux_dist, tmpdir, paths):
         """Validates the precedence of user-data files."""