Add experimental startup project settings cache, and add /cache_project_settings route to trigger caching explicitly

Author: manisandro

config_service.py

@@ -51,6 +51,9 @@ def __init__(self, logger):
             'QWC2_THEMES_CONFIG', os.path.join(qwc2_path, 'themesConfig.json')
         )
 
+        if os.environ.get("__QWC_CONFIG_SERVICE_PROJECT_SETTINGS_STARTUP_CACHE", "0") == "1":
+            self.cache_project_settings()
+
     def last_update(self):
         """Return UTC timestamp of last permissions update."""
         # get modification time of QWC2 themes config file
@@ -157,3 +160,6 @@ def resource_restrictions(self, resource_type, params, username, group):
         return {
             'restrictions': restrictions
         }
+
+    def cache_project_settings(self):
+        return self.permission_handlers["ogc"].cache_project_settings()

ogc_service_permission.py

@@ -443,3 +443,54 @@ def filter_permitted_layers(self, permitted_layers, permissions):
 
         # update restricted_group_layers
         permissions['restricted_group_layers'] = {}  # TODO
+
+    def collect_theme_urls(self, themes, theme_urls):
+        if "items" in themes:
+            for entry in themes["items"]:
+                theme_urls.add(entry["url"])
+        if "groups" in themes:
+            for theme_group in themes["groups"]:
+                self.collect_theme_urls(theme_group, theme_urls)
+
+    def cache_project_settings(self):
+        qwc2_path = os.environ.get('QWC2_PATH', 'qwc2/')
+        themes_config_path = os.environ.get(
+            'QWC2_THEMES_CONFIG', os.path.join(qwc2_path, 'themesConfig.json')
+        )
+        mtime = self.themesConfigMTime()
+
+        with open(themes_config_path) as fh:
+            data = json.load(fh)
+        # Collect themes
+        theme_urls = set()
+        themes = data["themes"] if "themes" in data else {}
+        self.collect_theme_urls(themes, theme_urls)
+
+        if not "WMS" in self.project_settings_cache:
+            self.project_settings_cache["WMS"] = {}
+
+        cached = []
+        for url in theme_urls:
+            if not url.startswith(self.qgis_server_url):
+                self.logger.warn("Not caching external WMS: %s" % url)
+                continue
+
+            ows_name = url[len(self.qgis_server_url):]
+            response = requests.get(
+                urljoin(self.qgis_server_url, ows_name),
+                params={
+                    'SERVICE': "WMS",
+                    'VERSION': '1.3.0',
+                    'REQUEST': 'GetProjectSettings'
+                },
+                timeout=30
+            )
+
+            if response.status_code == requests.codes.ok:
+                self.logger.info("Cached project settings for %s" % ows_name)
+                self.project_settings_cache["WMS"][ows_name] = {
+                    "document": response.content,
+                    "timestamp": mtime
+                }
+                cached.append(ows_name)
+        return {"cached_settings": cached}

server.py

@@ -27,6 +27,14 @@
     )]
 ])
 
+cache_project_settings_response = create_model(api, 'CacheProjectSettings', [
+    ['cached_settings', fields.Raw(
+        required=True,
+        description='List of service names for which settings were cached',
+        example=['name1', 'name2']
+    )]
+])
+
 resource_permissions_response = create_model(api, 'Resource permissions', [
     ['resource_type', fields.String(required=True, description='Resource type',
                                     example='map')],
@@ -65,6 +73,13 @@ def get(self):
         """Get timestamp of last permissions update"""
         return config_service.last_update()
 
+@api.route('/cache_project_settings')
+class CacheProjectSettings(Resource):
+    @api.doc('cache_project_settings')
+    @api.marshal_with(cache_project_settings_response)
+    def get(self):
+        """Cache all known project settings"""
+        return config_service.cache_project_settings()
 
 @api.route('/permissions/<resource_type>')
 @api.param('resource_type', 'Resource type (e.g. <i>map</i>, <i>layer</i>)',