mgr: add site package paths in PyModuleRegistry

before this change, we add the paths of site packages to sys.path
when starting subinterpretors for each of the mgr modules. this
works just fine. but in Python 3.11, it deprecates `PySys_SetPath()`
in favor of PyConfig machinary, which sets the module search paths
in PyConfig, before calling `Py_InitializeFromConfig()`. so, to
set the module search paths with the new machinary, we need to do
this in `PyModuleRegistry`, where we initialize the global Python
interpretor using the new PyConfig machinary. and since we've
switched to the new PyConfig machinary when compiling with Python 3.8
and up.

in this change, to unify the implementation of pre and post Python 3.8,
we set the module search paths in PyModuleRegistry. because PyConfig
imports the site packages by default, and we are allowed to append
a new path to the existing search paths, we just append the configured
`mgr_module_path` when compiling with Python 3.8 and up. and when it
comes to lower versions of Python, the existing behavior is preserved.

this change should silence the compiling warning like:

```
/var/ssd/ceph/src/mgr/PyModule.cc:368:20: warning: ‘void PySys_SetPath(const wchar_t*)’ is deprecated [-Wdeprecated-declarations]
  368 |       PySys_SetPath(const_cast<wchar_t*>(sys_path.c_str()));
      |       ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/python3.12/sysmodule.h:15:38: note: declared here
   15 | Py_DEPRECATED(3.11) PyAPI_FUNC(void) PySys_SetPath(const wchar_t *);
      |                                      ^~~~~~~~~~~~~
```

Signed-off-by: Kefu Chai <[email protected]>

src/mgr/PyModule.cc

@@ -47,7 +47,6 @@ std::string PyModule::mgr_store_prefix = "mgr/";
 
 
 using std::string;
-using std::wstring;
 
 // decode a Python exception into a string
 std::string handle_pyerror(
@@ -231,72 +230,6 @@ std::pair<int, std::string> PyModuleConfig::set_config(
   }
 }
 
-std::string PyModule::get_site_packages()
-{
-  std::stringstream site_packages;
-
-  // CPython doesn't auto-add site-packages dirs to sys.path for us,
-  // but it does provide a module that we can ask for them.
-  auto site_module = PyImport_ImportModule("site");
-  ceph_assert(site_module);
-
-  auto site_packages_fn = PyObject_GetAttrString(site_module, "getsitepackages");
-  if (site_packages_fn != nullptr) {
-    auto site_packages_list = PyObject_CallObject(site_packages_fn, nullptr);
-    ceph_assert(site_packages_list);
-
-    auto n = PyList_Size(site_packages_list);
-    for (Py_ssize_t i = 0; i < n; ++i) {
-      if (i != 0) {
-        site_packages << ":";
-      }
-      site_packages << PyUnicode_AsUTF8(PyList_GetItem(site_packages_list, i));
-    }
-
-    Py_DECREF(site_packages_list);
-    Py_DECREF(site_packages_fn);
-  } else {
-    // Fall back to generating our own site-packages paths by imitating
-    // what the standard site.py does.  This is annoying but it lets us
-    // run inside virtualenvs :-/
-
-    auto site_packages_fn = PyObject_GetAttrString(site_module, "addsitepackages");
-    ceph_assert(site_packages_fn);
-
-    auto known_paths = PySet_New(nullptr);
-    auto pArgs = PyTuple_Pack(1, known_paths);
-    PyObject_CallObject(site_packages_fn, pArgs);
-    Py_DECREF(pArgs);
-    Py_DECREF(known_paths);
-    Py_DECREF(site_packages_fn);
-
-    auto sys_module = PyImport_ImportModule("sys");
-    ceph_assert(sys_module);
-    auto sys_path = PyObject_GetAttrString(sys_module, "path");
-    ceph_assert(sys_path);
-
-    dout(1) << "sys.path:" << dendl;
-    auto n = PyList_Size(sys_path);
-    bool first = true;
-    for (Py_ssize_t i = 0; i < n; ++i) {
-      dout(1) << "  " << PyUnicode_AsUTF8(PyList_GetItem(sys_path, i)) << dendl;
-      if (first) {
-        first = false;
-      } else {
-        site_packages << ":";
-      }
-      site_packages << PyUnicode_AsUTF8(PyList_GetItem(sys_path, i));
-    }
-
-    Py_DECREF(sys_path);
-    Py_DECREF(sys_module);
-  }
-
-  Py_DECREF(site_module);
-
-  return site_packages.str();
-}
-
 PyObject* PyModule::init_ceph_logger()
 {
   auto py_logger = PyModule_Create(&ceph_logger_module);
@@ -357,13 +290,6 @@ int PyModule::load(PyThreadState *pMainThreadState)
       return -EINVAL;
     } else {
       pMyThreadState.set(thread_state);
-      // Configure sys.path to include mgr_module_path
-      string paths = (g_conf().get_val<std::string>("mgr_module_path") + ':' +
-                      get_site_packages() + ':');
-      wstring sys_path(wstring(begin(paths), end(paths)) + Py_GetPath());
-      PySys_SetPath(const_cast<wchar_t*>(sys_path.c_str()));
-      dout(10) << "Computed sys.path '"
-	       << string(begin(sys_path), end(sys_path)) << "'" << dendl;
     }
   }
   // Environment is all good, import the external module

src/mgr/PyModule.h

@@ -51,7 +51,6 @@ class PyModule
   mutable ceph::mutex lock = ceph::make_mutex("PyModule::lock");
 private:
   const std::string module_name;
-  std::string get_site_packages();
   int load_subclass_of(const char* class_name, PyObject** py_class);
 
   // Did the MgrMap identify this module as one that should run?

src/mgr/PyModuleRegistry.cc

@@ -66,6 +66,9 @@ void PyModuleRegistry::init()
   py_config.configure_c_stdio = 0;
   py_config.install_signal_handlers = 0;
   py_config.pathconfig_warnings = 0;
+  // site_import is 1 by default, but set it explicitly as we do import
+  // site packages manually for Python < 3.8
+  py_config.site_import = 1;
 
   PyStatus status;
   status = PyConfig_SetString(&py_config, &py_config.program_name, WCHAR(MGR_PYTHON_EXECUTABLE));
@@ -80,6 +83,15 @@ void PyModuleRegistry::init()
     PyImport_AppendInittab("ceph_logger", PyModule::init_ceph_logger);
   }
   PyImport_AppendInittab("ceph_module", PyModule::init_ceph_module);
+  // Configure sys.path to include mgr_module_path
+  auto pythonpath_env = g_conf().get_val<std::string>("mgr_module_path");
+  if (const char* pythonpath = getenv("PYTHONPATH")) {
+    pythonpath_env += ":";
+    pythonpath_env += pythonpath;
+  }
+  status = PyConfig_SetBytesString(&py_config, &py_config.pythonpath_env, pythonpath_env.data());
+  ceph_assertf(!PyStatus_Exception(status), "PyConfig_SetBytesString: %s:%s", status.func, status.err_msg);
+  dout(10) << "set PYTHONPATH to " << std::quoted(pythonpath_env) << dendl;
   status = Py_InitializeFromConfig(&py_config);
   ceph_assertf(!PyStatus_Exception(status), "Py_InitializeFromConfig: %s:%s", status.func, status.err_msg);
 #else
@@ -92,6 +104,14 @@ void PyModuleRegistry::init()
   Py_InitializeEx(0);
   const wchar_t *argv[] = {L"ceph-mgr"};
   PySys_SetArgv(1, (wchar_t**)argv);
+
+  std::string paths = (g_conf().get_val<std::string>("mgr_module_path") + ':' +
+		       get_site_packages() + ':');
+  std::wstring sys_path(begin(paths), end(paths));
+  sys_path += Py_GetPath();
+  PySys_SetPath(const_cast<wchar_t*>(sys_path.c_str()));
+  dout(10) << "Computed sys.path '"
+	   << std::string(begin(sys_path), end(sys_path)) << "'" << dendl;
 #endif // PY_VERSION_HEX >= 0x03080000
 #undef WCHAR
 
@@ -258,6 +278,72 @@ void PyModuleRegistry::active_start(
   }
 }
 
+std::string PyModuleRegistry::get_site_packages()
+{
+  std::stringstream site_packages;
+
+  // CPython doesn't auto-add site-packages dirs to sys.path for us,
+  // but it does provide a module that we can ask for them.
+  auto site_module = PyImport_ImportModule("site");
+  ceph_assert(site_module);
+
+  auto site_packages_fn = PyObject_GetAttrString(site_module, "getsitepackages");
+  if (site_packages_fn != nullptr) {
+    auto site_packages_list = PyObject_CallObject(site_packages_fn, nullptr);
+    ceph_assert(site_packages_list);
+
+    auto n = PyList_Size(site_packages_list);
+    for (Py_ssize_t i = 0; i < n; ++i) {
+      if (i != 0) {
+        site_packages << ":";
+      }
+      site_packages << PyUnicode_AsUTF8(PyList_GetItem(site_packages_list, i));
+    }
+
+    Py_DECREF(site_packages_list);
+    Py_DECREF(site_packages_fn);
+  } else {
+    // Fall back to generating our own site-packages paths by imitating
+    // what the standard site.py does.  This is annoying but it lets us
+    // run inside virtualenvs :-/
+
+    auto site_packages_fn = PyObject_GetAttrString(site_module, "addsitepackages");
+    ceph_assert(site_packages_fn);
+
+    auto known_paths = PySet_New(nullptr);
+    auto pArgs = PyTuple_Pack(1, known_paths);
+    PyObject_CallObject(site_packages_fn, pArgs);
+    Py_DECREF(pArgs);
+    Py_DECREF(known_paths);
+    Py_DECREF(site_packages_fn);
+
+    auto sys_module = PyImport_ImportModule("sys");
+    ceph_assert(sys_module);
+    auto sys_path = PyObject_GetAttrString(sys_module, "path");
+    ceph_assert(sys_path);
+
+    dout(1) << "sys.path:" << dendl;
+    auto n = PyList_Size(sys_path);
+    bool first = true;
+    for (Py_ssize_t i = 0; i < n; ++i) {
+      dout(1) << "  " << PyUnicode_AsUTF8(PyList_GetItem(sys_path, i)) << dendl;
+      if (first) {
+        first = false;
+      } else {
+        site_packages << ":";
+      }
+      site_packages << PyUnicode_AsUTF8(PyList_GetItem(sys_path, i));
+    }
+
+    Py_DECREF(sys_path);
+    Py_DECREF(sys_module);
+  }
+
+  Py_DECREF(site_module);
+
+  return site_packages.str();
+}
+
 std::vector<std::string> PyModuleRegistry::probe_modules(const std::string &path) const
 {
   const auto opt = g_conf().get_val<std::string>("mgr_disabled_modules");

src/mgr/PyModuleRegistry.h

@@ -55,6 +55,7 @@ class PyModuleRegistry
   // before ClusterState exists.
   MgrMap mgr_map;
 
+  static std::string get_site_packages();
   /**
    * Discover python modules from local disk
    */