From 1001e0f4bd3dc6be56f65b6727c3d5c71012bfd5 Mon Sep 17 00:00:00 2001
From: Luca Boccassi <luca.boccassi@microsoft.com>
Date: Wed, 26 Feb 2020 22:27:32 +0000
Subject: [PATCH] Allow to install extensions in the system path via packages

On Linux, check if there are extension in the system Python
library path (eg: /usr/lib/python3/dist-packages/azure-cli-extensions).

This allows extensions to be installed via system packages in
dist-packages, and registered by simply creating an extension directory
and symlinking the egg-info and the module.

EG:

$ ls -l /usr/lib/python3/dist-packages/azure-cli-extensions/azure-devops/
total 0
lrwxrwxrwx 1 root root 18 Feb 23 12:31 azext_devops -> ../../azext_devops
lrwxrwxrwx 1 root root 34 Feb 23 12:31 azure_devops-0.17.0.egg-info -> ../../azure_devops-0.17.0.egg-info
$ az extension list
[
  {
    "extensionType": "whl",
    "name": "azure-devops",
    "version": "0.17.0"
  }
]

Locally installed extensions still have higher priority if available.
---
 .../azure/cli/core/extension/__init__.py      | 20 +++++++++++++++++--
 src/azure-cli-core/setup.py                   |  1 +
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/azure-cli-core/azure/cli/core/extension/__init__.py b/src/azure-cli-core/azure/cli/core/extension/__init__.py
index 574270c8cf0..43aa5ec2777 100644
--- a/src/azure-cli-core/azure/cli/core/extension/__init__.py
+++ b/src/azure-cli-core/azure/cli/core/extension/__init__.py
@@ -7,9 +7,11 @@
 import traceback
 import json
 import re
+import sys
+import pkginfo
 
 from azure.cli.core._config import GLOBAL_CONFIG_DIR, ENV_VAR_PREFIX
-
+from distutils.sysconfig import get_python_lib
 from knack.config import CLIConfig
 from knack.log import get_logger
 
@@ -19,6 +21,7 @@
 EXTENSIONS_DIR = os.path.expanduser(_CUSTOM_EXT_DIR) if _CUSTOM_EXT_DIR else os.path.join(GLOBAL_CONFIG_DIR,
                                                                                           'cliextensions')
 DEV_EXTENSION_SOURCES = _DEV_EXTENSION_SOURCES.split(',') if _DEV_EXTENSION_SOURCES else []
+EXTENSIONS_SYS_DIR = os.path.join(get_python_lib(), 'azure-cli-extensions') if sys.platform.startswith('linux') else ""
 
 EXTENSIONS_MOD_PREFIX = 'azext_'
 
@@ -33,7 +36,7 @@
 WHEEL_INFO_RE = re.compile(
     r"""^(?P<namever>(?P<name>.+?)(-(?P<ver>\d.+?))?)
     ((-(?P<build>\d.*?))?-(?P<pyver>.+?)-(?P<abi>.+?)-(?P<plat>.+?)
-    \.whl|\.dist-info)$""",
+    \.whl|\.dist-info|\.egg-info)$""",
     re.VERBOSE).match
 
 logger = get_logger(__name__)
@@ -136,9 +139,14 @@ def get_metadata(self):
                 if os.path.isfile(whl_metadata_filepath):
                     with open(whl_metadata_filepath) as f:
                         metadata.update(json.loads(f.read()))
+                elif os.path.isfile(os.path.join(dist_info_dirname, 'PKG-INFO')):
+                    metadata.update(pkginfo.Develop(dist_info_dirname).__dict__)
 
         return metadata
 
+    def __eq__(self, other):
+        return other.name == self.name
+
     @staticmethod
     def get_azext_metadata(ext_dir):
         azext_metadata = None
@@ -162,6 +170,14 @@ def get_all():
                 pattern = os.path.join(ext_path, '*.*-info')
                 if os.path.isdir(ext_path) and glob(pattern):
                     exts.append(WheelExtension(ext_name, ext_path))
+        if os.path.isdir(EXTENSIONS_SYS_DIR):
+            for ext_name in os.listdir(EXTENSIONS_SYS_DIR):
+                ext_path = os.path.join(EXTENSIONS_SYS_DIR, ext_name)
+                pattern = os.path.join(ext_path, '*.*-info')
+                if os.path.isdir(ext_path) and glob(pattern):
+                    ext = WheelExtension(ext_name, ext_path)
+                    if ext not in exts:
+                        exts.append(ext)
         return exts
 
 
diff --git a/src/azure-cli-core/setup.py b/src/azure-cli-core/setup.py
index 08cddb8b267..79d3a8b211c 100644
--- a/src/azure-cli-core/setup.py
+++ b/src/azure-cli-core/setup.py
@@ -61,6 +61,7 @@
     'msrest>=0.4.4',
     'msrestazure>=0.6.2',
     'paramiko>=2.0.8,<3.0.0',
+    'pkginfo',
     'PyJWT',
     'pyopenssl>=17.1.0',  # https://github.com/pyca/pyopenssl/pull/612
     'pyyaml',