Python code modernization, 5/n (#1165)

* Address raise-missing-from.

* Address simplifiable-if-expression.

* Address unnecessary-dunder-call.

* Address unnecessary-pass.

* Address use-list-literal.

* Address unused-variable.

* Address use-dict-literal.

plugins/connection/docker.py

@@ -167,8 +167,8 @@ class Connection(ConnectionBase):
         else:
             try:
                 self.docker_cmd = get_bin_path("docker")
-            except ValueError:
-                raise AnsibleError("docker command not found in PATH")
+            except ValueError as exc:
+                raise AnsibleError("docker command not found in PATH") from exc
 
     @staticmethod
     def _sanitize_version(version):
@@ -426,7 +426,7 @@ class Connection(ConnectionBase):
                             )
 
                         chunks = b""
-                        for key, event in events:
+                        for key, dummy_event in events:
                             if key.fileobj == p.stdout:
                                 chunk = p.stdout.read()
                                 if chunk:
@@ -523,10 +523,10 @@ class Connection(ConnectionBase):
                 p = subprocess.Popen(
                     args, stdin=in_file, stdout=subprocess.PIPE, stderr=subprocess.PIPE
                 )
-            except OSError:
+            except OSError as exc:
                 raise AnsibleError(
                     "docker connection requires dd command in the container to put files"
-                )
+                ) from exc
             stdout, stderr = p.communicate()
 
             if p.returncode != 0:
@@ -588,10 +588,10 @@ class Connection(ConnectionBase):
                             stdout=out_file,
                             stderr=subprocess.PIPE,
                         )
-                    except OSError:
+                    except OSError as exc:
                         raise AnsibleError(
                             "docker connection requires dd command in the container to put files"
-                        )
+                        ) from exc
                     stdout, stderr = pp.communicate()
 
                     if pp.returncode != 0:

plugins/connection/docker_api.py

@@ -158,15 +158,15 @@ class Connection(ConnectionBase):
             if not_found_can_be_resource:
                 raise AnsibleConnectionFailure(
                     f'Could not find container "{remote_addr}" or resource in it ({e})'
-                )
+                ) from e
             raise AnsibleConnectionFailure(
                 f'Could not find container "{remote_addr}" ({e})'
-            )
+            ) from e
         except APIError as e:
             if e.response is not None and e.response.status_code == 409:
                 raise AnsibleConnectionFailure(
                     f'The container "{remote_addr}" has been paused ({e})'
-                )
+                ) from e
             self.client.fail(
                 f'An unexpected Docker error occurred for container "{remote_addr}": {e}'
             )
@@ -183,7 +183,7 @@ class Connection(ConnectionBase):
         super().__init__(play_context, new_stdin, *args, **kwargs)
 
         self.client = None
-        self.ids = dict()
+        self.ids = {}
 
         # Windows uses Powershell modules
         if getattr(self._shell, "_IS_WINDOWS", False):
@@ -239,7 +239,7 @@ class Connection(ConnectionBase):
             host=self.get_option("remote_addr"),
         )
 
-        need_stdin = True if (in_data is not None) or do_become else False
+        need_stdin = bool((in_data is not None) or do_become)
 
         data = {
             "Container": self.get_option("remote_addr"),
@@ -393,7 +393,7 @@ class Connection(ConnectionBase):
             except Exception as e:
                 raise AnsibleConnectionFailure(
                     f'Error while determining user and group ID of current user in container "{remote_addr}": {e}\nGot value: {ids!r}'
-                )
+                ) from e
 
         user_id, group_id = self.ids[self.actual_user]
         try:
@@ -411,9 +411,9 @@ class Connection(ConnectionBase):
                 not_found_can_be_resource=True,
             )
         except DockerFileNotFound as exc:
-            raise AnsibleFileNotFound(to_native(exc))
+            raise AnsibleFileNotFound(to_native(exc)) from exc
         except DockerFileCopyError as exc:
-            raise AnsibleConnectionFailure(to_native(exc))
+            raise AnsibleConnectionFailure(to_native(exc)) from exc
 
     def fetch_file(self, in_path, out_path):
         """Fetch a file from container to local."""
@@ -439,9 +439,9 @@ class Connection(ConnectionBase):
                 not_found_can_be_resource=True,
             )
         except DockerFileNotFound as exc:
-            raise AnsibleFileNotFound(to_native(exc))
+            raise AnsibleFileNotFound(to_native(exc)) from exc
         except DockerFileCopyError as exc:
-            raise AnsibleConnectionFailure(to_native(exc))
+            raise AnsibleConnectionFailure(to_native(exc)) from exc
 
     def close(self):
         """Terminate the connection. Nothing to do for Docker"""

plugins/connection/nsenter.py

@@ -178,7 +178,7 @@ class Connection(ConnectionBase):
                             )
 
                         chunks = b""
-                        for key, event in events:
+                        for key, dummy_event in events:
                             if key.fileobj == p.stdout:
                                 chunk = p.stdout.read()
                                 if chunk:
@@ -244,11 +244,13 @@ class Connection(ConnectionBase):
         try:
             with open(to_bytes(in_path, errors="surrogate_or_strict"), "rb") as in_file:
                 in_data = in_file.read()
-            rc, out, err = self.exec_command(cmd=["tee", out_path], in_data=in_data)
+            rc, dummy_out, err = self.exec_command(
+                cmd=["tee", out_path], in_data=in_data
+            )
             if rc != 0:
                 raise AnsibleError(f"failed to transfer file to {out_path}: {err}")
         except IOError as e:
-            raise AnsibleError(f"failed to transfer file to {out_path}: {e}")
+            raise AnsibleError(f"failed to transfer file to {out_path}: {e}") from e
 
     def fetch_file(self, in_path, out_path):
         super().fetch_file(in_path, out_path)
@@ -268,7 +270,9 @@ class Connection(ConnectionBase):
             ) as out_file:
                 out_file.write(out)
         except IOError as e:
-            raise AnsibleError(f"failed to transfer file to {to_native(out_path)}: {e}")
+            raise AnsibleError(
+                f"failed to transfer file to {to_native(out_path)}: {e}"
+            ) from e
 
     def close(self):
         """terminate the connection; nothing to do here"""