add APP_INSTALL_DIR to example_app.py, copy trusted root.json directl…

…y from repo example

.gitignore

@@ -1,6 +1,7 @@
 # dirs
 __pycache__/
 examples/client/cache/
+examples/client/programs/
 examples/repo/keystore/
 examples/repo/content/
 

examples/client/example_app.py

@@ -6,31 +6,47 @@
 
 logger = logging.getLogger(__name__)
 
-# This example stores all files in the notsotuf/examples/client directory
-BASE_DIR = pathlib.Path(__file__).resolve().parent
+# To get started, create a local example repository by running the
+# repo_workflow_example.py script. Then serve the repo content directory on
+# localhost:
+#
+#   python -m http.server -d examples/repo/content
 
 # App info
 APP_NAME = 'example_app'
 CURRENT_VERSION = '1.0'
+
+# For this example, all files are stored in the notsotuf/examples/client
+# directory. On Windows 10, a typical location for the BASE_DIR would be
+# %PROGRAMDATA%\MyApp (per-machine), or %LOCALAPPDATA%\MyApp (per-user).
+BASE_DIR = pathlib.Path(__file__).resolve().parent
+
+# On Windows 10, typical app installation locations are %PROGRAMFILES%\MyApp
+# (per-machine) or %LOCALAPPDATA%\Programs\MyApp (per-user). Also see:
+# https://docs.microsoft.com/en-us/windows/win32/msi/installation-context
+APP_INSTALL_DIR = BASE_DIR / 'programs' / APP_NAME
+
 # App directories
 CACHE_DIR = BASE_DIR / 'cache'
 METADATA_DIR = CACHE_DIR / 'metadata'
 TARGET_DIR = CACHE_DIR / 'targets'
+
 # Update-server urls
 METADATA_BASE_URL = 'http://localhost:8000/metadata/'
 TARGET_BASE_URL = 'http://localhost:8000/targets/'
 
 
 def main():
     # The app must ensure dirs exist
-    for dir_path in [METADATA_DIR, TARGET_DIR]:
+    for dir_path in [APP_INSTALL_DIR, METADATA_DIR, TARGET_DIR]:
         dir_path.mkdir(exist_ok=True, parents=True)
 
     # The app must be shipped with a trusted "root.json" metadata file (
     # created using tools.repo), and must ensure this file can found in the
     # specified metadata_dir. The root metadata file lists all trusted keys
-    # and TUF roles.
-    source_path = BASE_DIR / 'trusted_root.json'
+    # and TUF roles. In this example we copy the root.json file from the
+    # repo, but normally it would be included in the app distribution.
+    source_path = BASE_DIR.parent / 'repo' / 'content' / 'metadata' / 'root.json'
     destination_path = METADATA_DIR / 'root.json'
     if not destination_path.exists():
         shutil.copy(src=source_path, dst=destination_path)
@@ -39,6 +55,7 @@ def main():
     # Create update client
     client = Client(
         app_name=APP_NAME,
+        app_install_dir=APP_INSTALL_DIR,
         current_version=CURRENT_VERSION,
         metadata_dir=METADATA_DIR,
         metadata_base_url=METADATA_BASE_URL,