feat: lazy load ansible imports

Author: PaulFarault

tdp/cli/commands/default_diff.py

@@ -10,9 +10,9 @@
 from typing import TYPE_CHECKING, Optional
 
 import click
-from ansible.utils.vars import merge_hash
 
 from tdp.cli.params import collections_option, vars_option
+from tdp.core.ansible_loader import AnsibleLoader
 from tdp.core.constants import DEFAULT_VARS_DIRECTORY_NAME
 from tdp.core.variables import ClusterVariables, Variables
 
@@ -73,7 +73,7 @@ def service_diff(collections, service):
             with Variables(default_service_vars_filepath).open(
                 "r"
             ) as default_variables:
-                default_service_varfile = merge_hash(
+                default_service_varfile = AnsibleLoader.load_merge_hash()(
                     default_service_varfile, default_variables
                 )
 

tdp/core/ansible_loader.py

@@ -0,0 +1,102 @@
+# Copyright 2022 TOSIT.IO
+# SPDX-License-Identifier: Apache-2.0
+
+
+class AnsibleLoader:
+    """Lazy loader for Ansible classes and functions.
+
+    This class is required as ansible automatically generate a config when imported.
+    """
+
+    _merge_hash = None
+    _from_yaml = None
+    _AnsibleDumper = None
+    _InventoryCLI = None
+    _InventoryReader = None
+    _InventoryManager = None
+    _CustomInventoryCLI = None
+
+    @classmethod
+    def load_merge_hash(cls):
+        """Load the merge_hash function from ansible."""
+        if cls._merge_hash is None:
+            from ansible.utils.vars import merge_hash
+
+            cls._merge_hash = merge_hash
+
+        return cls._merge_hash
+
+    @classmethod
+    def load_from_yaml(cls):
+        """Load the from_yaml function from ansible."""
+        if cls._from_yaml is None:
+            from ansible.parsing.utils.yaml import from_yaml
+
+            cls._from_yaml = from_yaml
+
+        return cls._from_yaml
+
+    @classmethod
+    def load_AnsibleDumper(cls):
+        """Load the AnsibleDumper class from ansible."""
+        if cls._AnsibleDumper is None:
+            from ansible.parsing.yaml.dumper import AnsibleDumper
+
+            cls._AnsibleDumper = AnsibleDumper
+
+        return cls._AnsibleDumper
+
+    @classmethod
+    def load_InventoryCLI(cls):
+        """Load the InventoryCLI class from ansible."""
+        if cls._InventoryCLI is None:
+            from ansible.cli.inventory import InventoryCLI
+
+            cls._InventoryCLI = InventoryCLI
+
+        return cls._InventoryCLI
+
+    @classmethod
+    def load_InventoryReader(cls):
+        """Load the InventoryReader class from ansible."""
+        if cls._InventoryReader is None:
+            from tdp.core.inventory_reader import InventoryReader
+
+            cls._InventoryReader = InventoryReader
+
+        return cls._InventoryReader
+
+    @classmethod
+    def load_InventoryManager(cls):
+        """Load the InventoryManager class from ansible."""
+        if cls._InventoryManager is None:
+            from ansible.inventory.manager import InventoryManager
+
+            cls._InventoryManager = InventoryManager
+
+        return cls._InventoryManager
+
+    @classmethod
+    def get_CustomInventoryCLI(cls):
+        if cls._CustomInventoryCLI is None:
+
+            class CustomInventoryCLI(cls.load_InventoryCLI()):
+                """Represent a custom Ansible inventory CLI which does nothing.
+                This is used to load inventory files with Ansible code.
+                """
+
+                def __init__(self):
+                    super().__init__(["program", "--list"])
+                    # "run" must be called from CLI (the parent of InventoryCLI), to
+                    # initialize context (reading ansible.cfg for example).
+                    super(cls.load_InventoryCLI(), self).run()
+                    # Get InventoryManager instance
+                    _, self.inventory, _ = self._play_prereqs()
+
+                # Avoid call InventoryCLI "run", we do not need to run InventoryCLI
+                def run(self):
+                    pass
+
+            cls._CustomInventoryCLI = CustomInventoryCLI()
+
+        return cls._CustomInventoryCLI

tdp/core/inventory_reader.py

@@ -1,45 +1,29 @@
 # Copyright 2022 TOSIT.IO
 # SPDX-License-Identifier: Apache-2.0
 
-from typing import Optional, TextIO
+from typing import TYPE_CHECKING, Optional, TextIO
 
 import yaml
-from ansible.cli.inventory import InventoryCLI
-from ansible.inventory.manager import InventoryManager
+
+from tdp.core.ansible_loader import AnsibleLoader
 
 try:
     from yaml import CLoader as Loader
 except ImportError:
     from yaml import Loader
 
 
-# From ansible/cli/inventory.py
-class _CustomInventoryCLI(InventoryCLI):
-    """Represent a custom Ansible inventory CLI which does nothing.
-    This is used to load inventory files with Ansible code.
-    """
-
-    def __init__(self):
-        super().__init__(["program", "--list"])
-        # "run" must be called from CLI (the parent of InventoryCLI), to
-        # initialize context (reading ansible.cfg for example).
-        super(InventoryCLI, self).run()
-        # Get InventoryManager instance
-        _, self.inventory, _ = self._play_prereqs()
-
-    # Avoid call InventoryCLI "run", we do not need to run InventoryCLI
-    def run(self):
-        pass
-
-
-custom_inventory_cli_instance = _CustomInventoryCLI()
+if TYPE_CHECKING:
+    from ansible.inventory.manager import InventoryManager
 
 
 class InventoryReader:
     """Represent an Ansible inventory reader."""
 
-    def __init__(self, inventory: Optional[InventoryManager] = None):
-        self.inventory = inventory or custom_inventory_cli_instance.inventory
+    def __init__(self, inventory: Optional["InventoryManager"] = None):
+        if inventory is None:
+            inventory = AnsibleLoader.get_CustomInventoryCLI().inventory
+        self.inventory = inventory
 
     def get_hosts(self, *args, **kwargs) -> list[str]:
         """Takes a pattern or list of patterns and returns a list of matching

tdp/core/variables/variables.py

@@ -10,10 +10,8 @@
 from weakref import proxy
 
 import yaml
-from ansible.parsing.utils.yaml import from_yaml
-from ansible.parsing.yaml.dumper import AnsibleDumper
-from ansible.utils.vars import merge_hash
 
+from tdp.core.ansible_loader import AnsibleLoader
 from tdp.core.types import PathLike
 
 
@@ -90,7 +88,7 @@ def merge(self, mapping: MutableMapping) -> None:
         Args:
             mapping: Mapping to merge.
         """
-        self._content = merge_hash(self._content, mapping)
+        self._content = AnsibleLoader.load_merge_hash()(self._content, mapping)
 
     def __getitem__(self, key):
         return self._content.__getitem__(key)
@@ -131,7 +129,10 @@ def __init__(self, path: Path, mode: Optional[str] = None):
         self._file_path = path
         self._file_descriptor = open(self._file_path, mode or "r+")
         # Initialize the content of the variables file
-        super().__init__(content=from_yaml(self._file_descriptor) or {}, name=path.name)
+        super().__init__(
+            content=AnsibleLoader.load_from_yaml()(self._file_descriptor) or {},
+            name=path.name,
+        )
 
     def __enter__(self) -> _VariablesIOWrapper:
         return proxy(self)
@@ -152,7 +153,12 @@ def _flush_on_disk(self) -> None:
         # Write the content of the variables file on disk
         self._file_descriptor.seek(0)
         self._file_descriptor.write(
-            yaml.dump(self._content, Dumper=AnsibleDumper, sort_keys=False, width=1000)
+            yaml.dump(
+                self._content,
+                Dumper=AnsibleLoader.load_AnsibleDumper(),
+                sort_keys=False,
+                width=1000,
+            )
         )
         self._file_descriptor.truncate()
         self._file_descriptor.flush()