Remove getcwd to load WAAgent properly and not fall to backup

VMBackup/README.md

@@ -0,0 +1,64 @@
+# VMBackup Extension
+
+Linux guest extension used by the **Azure Backup** service to take
+application-consistent backups of Linux VMs running in Azure.
+
+> **Note:** This extension is intended to be installed and managed by Azure
+> Backup. Installing it manually outside that context is not supported.
+
+## Deployment
+
+The extension is deployed automatically as part of the first scheduled backup
+after a VM is configured for backup. To configure a VM for backup, see:
+
+- [Azure Portal](https://docs.microsoft.com/azure/backup/quick-backup-vm-portal)
+- [Azure PowerShell](https://docs.microsoft.com/azure/backup/quick-backup-vm-powershell)
+- [Azure CLI](https://docs.microsoft.com/azure/backup/quick-backup-vm-cli)
+
+## Repository layout
+
+```
+VMBackup/
+├── main/          Production source. Runs inside the target Linux VM.
+├── test/          Unit tests and test helpers (not shipped in the zip).
+├── references/    Vendored dependencies.
+└── README.md      This file.
+```
+
+## Running unit tests
+
+Tests live under `VMBackup/test/` and are written as `unittest.TestCase`
+subclasses. The test runner requires **Python 3.6 or newer**. The
+extension's own runtime Python compatibility is unchanged and continues to
+be validated by manual VM deployment.
+
+Run all commands from the `VMBackup/` directory.
+
+### Option A — `unittest` (no install required)
+
+```sh
+python -m unittest discover -s test -p "test_*.py" -v
+```
+
+### Option B — `pytest` (nicer output, optional)
+
+```sh
+pip install -r test/requirements.txt
+pytest test/ -v
+```
+
+Both runners discover the same test files; pick whichever you prefer.
+
+## Adding tests
+
+Place a test for `main/<Pkg>/<Module>.py` at
+`test/unit/<pkg>/test_<module>.py` (lowercase package directory and file name).
+
+```
+main/Utils/WAAgentUtil.py   →   test/unit/utils/test_waagent_util.py
+```
+
+If a test needs filesystem staging, mocks, or other module-specific
+scaffolding, add a fixtures module under `test/helpers/` (e.g.
+`test/helpers/waagent_fixtures.py`) rather than putting that logic into
+`test/helpers/tools.py`. Keep `tools.py` for genuinely shared utilities.

VMBackup/main/Utils/WAAgentUtil.py

@@ -41,10 +41,10 @@
 # it as a submodule of current module
 #
 def searchWAAgent():
-    agentPath = os.path.join(os.getcwd(), "main/WaagentLib.py")
+    agentPath = os.path.join(os.path.dirname(os.path.abspath(__file__)), os.pardir, "WaagentLib.py")
     if(os.path.isfile(agentPath)):
         return agentPath
-    user_paths = os.environ['PYTHONPATH'].split(os.pathsep)
+    user_paths = os.environ.get('PYTHONPATH', '').split(os.pathsep)
     for user_path in user_paths:
         agentPath = os.path.join(user_path, 'waagent')
         if(os.path.isfile(agentPath)):
@@ -55,7 +55,7 @@ def searchWAAgentOld():
     agentPath = '/usr/sbin/waagent'
     if(os.path.isfile(agentPath)):
         return agentPath
-    user_paths = os.environ['PYTHONPATH'].split(os.pathsep)
+    user_paths = os.environ.get('PYTHONPATH', '').split(os.pathsep)
     for user_path in user_paths:
         agentPath = os.path.join(user_path, 'waagent')
         if(os.path.isfile(agentPath)):

VMBackup/main/handle.py

@@ -722,7 +722,8 @@ def thread_for_log_upload():
     backup_logger.commit(para_parser.logsBlobUri)
 
 def start_daemon():
-    args = [os.path.join(os.getcwd(), "main/handle.sh"), "daemon"]
+    handle_sh_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), "handle.sh")
+    args = [handle_sh_path, "daemon"]
     #This process will start a new background process by calling
     #    handle.py -daemon
     #to run the script and will exit itself immediatelly.

VMBackup/test/helpers/tools.py

@@ -0,0 +1,26 @@
+"""
+Generic helpers shared by VMBackup unit tests.
+
+This module is intentionally small and dependency-free (stdlib only). Anything
+that's specific to one production module belongs in a per-feature fixtures
+module under this directory, not here.
+"""
+
+import os
+import sys
+
+
+# Repo paths. test/helpers/tools.py -> ../.. = VMBackup/
+VMBACKUP_DIR = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir))
+MAIN_DIR = os.path.join(VMBACKUP_DIR, "main")
+UTILS_DIR = os.path.join(MAIN_DIR, "Utils")
+
+
+def purge_modules(*names):
+    """Drop the named modules from `sys.modules`.
+
+    Useful when a test needs to force a fresh import of a module whose
+    module-level (import-time) code is part of the behavior under test.
+    """
+    for name in names:
+        sys.modules.pop(name, None)

VMBackup/test/helpers/waagent_fixtures.py

@@ -0,0 +1,94 @@
+"""
+Test fixtures for `main/Utils/WAAgentUtil.py`.
+
+`WAAgentUtil.py` runs filesystem-dependent code at import time to locate and
+load a `waagent` module. To exercise that behavior in tests, we need to
+stage a fresh, minimal copy of the extension tree on disk and import the
+module against it.
+"""
+
+import importlib
+import os
+import shutil
+import sys
+
+from test.helpers import tools
+
+
+# Modules that get cached in `sys.modules` once WAAgentUtil is imported.
+# Tests must drop these before re-importing so module-level code re-runs.
+_CACHED_MODULES = ("waagent", "WAAgentUtil", "Utils", "Utils.WAAgentUtil")
+
+# Minimal stand-in for `main/WaagentLib.py`. The real file is large; tests
+# only need the symbols WAAgentUtil's module-level code touches.
+_BUNDLED_LIB_STUB = '''
+"""Test stub for WaagentLib.py."""
+SOURCE = "bundled"
+
+def RunGetOutput(cmd, chk_err=True):
+    return 0, ""
+
+def AddExtensionEvent(*args, **kwargs):
+    pass
+
+class WALAEventOperation:
+    HeartBeat = "HeartBeat"
+    Provision = "Provision"
+    Install = "Install"
+    UnInstall = "UnInstall"
+    Disable = "Disable"
+    Enable = "Enable"
+    Download = "Download"
+    Upgrade = "Upgrade"
+    Update = "Update"
+'''
+
+
+def stage_extension_tree(dest_dir, with_bundled_lib=True, bundled_lib_source=None):
+    """Lay out a minimal extension tree under `dest_dir` and return the path
+    to the staged `main/` directory.
+
+    Layout produced::
+
+        dest_dir/
+          main/
+            __init__.py
+            WaagentLib.py        (only if with_bundled_lib=True)
+            Utils/
+              __init__.py
+              WAAgentUtil.py     (copied verbatim from the repo)
+
+    `bundled_lib_source`, when given, overrides the contents written to
+    `WaagentLib.py`.
+    """
+    main_dir = os.path.join(dest_dir, "main")
+    utils_dir = os.path.join(main_dir, "Utils")
+    os.makedirs(utils_dir, exist_ok=True)
+    open(os.path.join(main_dir, "__init__.py"), "w").close()
+    open(os.path.join(utils_dir, "__init__.py"), "w").close()
+    shutil.copy(
+        os.path.join(tools.UTILS_DIR, "WAAgentUtil.py"),
+        os.path.join(utils_dir, "WAAgentUtil.py"),
+    )
+    if with_bundled_lib:
+        with open(os.path.join(main_dir, "WaagentLib.py"), "w") as f:
+            f.write(bundled_lib_source if bundled_lib_source is not None else _BUNDLED_LIB_STUB)
+    return main_dir
+
+
+def import_waagent_util_from(main_dir):
+    """Force a fresh import of `Utils.WAAgentUtil` against a staged tree."""
+    purge_module_cache()
+    sys.path.insert(0, main_dir)
+    try:
+        return importlib.import_module("Utils.WAAgentUtil")
+    finally:
+        try:
+            sys.path.remove(main_dir)
+        except ValueError:
+            pass
+
+
+def purge_module_cache():
+    """Drop any cached WAAgentUtil-related modules from `sys.modules`."""
+    tools.purge_modules(*_CACHED_MODULES)

VMBackup/test/requirements.txt

@@ -0,0 +1,14 @@
+# Optional dependencies for running VMBackup unit tests.
+#
+# The tests themselves are written as unittest.TestCase subclasses and require
+# nothing beyond the Python standard library. You can run them with:
+#
+#     python -m unittest discover -s test -p "test_*.py"
+#
+# Installing pytest is optional. It produces nicer failure output and supports
+# parallel execution, but it is not required.
+#
+#     pip install -r test/requirements.txt
+#     pytest test/
+#
+pytest>=6.0

VMBackup/test/unit/utils/test_waagent_util.py

@@ -0,0 +1,69 @@
+"""Tests for `main/Utils/WAAgentUtil.py` — module-level loading behavior."""
+
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+
+# Make `from test.helpers import ...` resolvable when running from VMBackup root.
+_HERE = os.path.dirname(os.path.abspath(__file__))
+_VMBACKUP_DIR = os.path.abspath(os.path.join(_HERE, os.pardir, os.pardir, os.pardir))
+if _VMBACKUP_DIR not in sys.path:
+    sys.path.insert(0, _VMBACKUP_DIR)
+
+from test.helpers import waagent_fixtures  # noqa: E402
+
+
+class WAAgentUtilLoadTests(unittest.TestCase):
+    """Verifies that WAAgentUtil reliably locates and loads the bundled
+    `WaagentLib.py` regardless of process CWD or `PYTHONPATH` state."""
+
+    def setUp(self):
+        self._original_cwd = os.getcwd()
+        self._tmp_root = tempfile.mkdtemp(prefix="vmbackup-test-ext-")
+        self._unrelated_cwd = tempfile.mkdtemp(prefix="vmbackup-test-cwd-")
+        # Exercise the unset case — see test_pythonpath_unset_does_not_raise.
+        self._saved_pythonpath = os.environ.pop("PYTHONPATH", None)
+
+    def tearDown(self):
+        os.chdir(self._original_cwd)
+        shutil.rmtree(self._tmp_root, ignore_errors=True)
+        shutil.rmtree(self._unrelated_cwd, ignore_errors=True)
+        if self._saved_pythonpath is not None:
+            os.environ["PYTHONPATH"] = self._saved_pythonpath
+        waagent_fixtures.purge_module_cache()
+
+    def test_loads_bundled_lib_when_cwd_is_extension_root(self):
+        """Happy path: CWD == extension root."""
+        main_dir = waagent_fixtures.stage_extension_tree(self._tmp_root)
+        os.chdir(self._tmp_root)
+
+        mod = waagent_fixtures.import_waagent_util_from(main_dir)
+
+        self.assertEqual(getattr(mod.waagent, "SOURCE", None), "bundled")
+        self.assertEqual(mod.GetPathUsed(), 1)
+
+    def test_loads_bundled_lib_when_cwd_is_not_extension_root(self):
+        """The bundled lib must be located via `__file__`, not `os.getcwd()`."""
+        main_dir = waagent_fixtures.stage_extension_tree(self._tmp_root)
+        os.chdir(self._unrelated_cwd)
+        self.assertNotEqual(os.getcwd(), self._tmp_root)
+
+        mod = waagent_fixtures.import_waagent_util_from(main_dir)
+
+        self.assertEqual(getattr(mod.waagent, "SOURCE", None), "bundled")
+        self.assertEqual(mod.GetPathUsed(), 1)
+
+    def test_pythonpath_unset_does_not_raise(self):
+        """Module load must tolerate `PYTHONPATH` being absent from the env."""
+        self.assertNotIn("PYTHONPATH", os.environ)
+        main_dir = waagent_fixtures.stage_extension_tree(self._tmp_root)
+
+        mod = waagent_fixtures.import_waagent_util_from(main_dir)
+
+        self.assertEqual(getattr(mod.waagent, "SOURCE", None), "bundled")
+
+
+if __name__ == "__main__":
+    unittest.main()