(Temporary) caching cdn handler until we sort out bundling

js/loader.js

@@ -12,7 +12,8 @@ var requirePromise = function (pkg) {
 };
 
 export function requireLoader(moduleName, moduleVersion) {
-    return requirePromise(["" + moduleName]).catch(function (err) {
+    var path = `/voila/require/${moduleName}@${moduleVersion}`
+    return requirePromise([path]).catch(function (err) {
         var failedId = err.requireModules && err.requireModules[0];
         if (failedId) {
             console.log(`Falling back to unpkg.com for ${moduleName}@${moduleVersion}`);

voila/app.py

@@ -26,6 +26,7 @@
 from .handler import VoilaHandler
 from .treehandler import VoilaTreeHandler
 from .watchdog import WatchDogHandler
+from .requirehandler import RequireHandler
 
 _kernel_id_regex = r"(?P<kernel_id>\w+-\w+-\w+-\w+-\w+)"
 
@@ -110,7 +111,9 @@ def start(self):
             ]
         )
 
+        _require_regex = '(.*)'
         handlers = [
+            (r'/voila/require/%s' % _require_regex, RequireHandler),
             (r'/api/kernels/%s' % _kernel_id_regex, KernelHandler),
             (r'/api/kernels/%s/channels' % _kernel_id_regex, ZMQChannelsHandler),
             (
@@ -148,7 +151,6 @@ def start(self):
 
         contents_manager = LargeFileManager()  # TODO: make this configurable like notebook
 
-
         app = tornado.web.Application(
             handlers,
             kernel_manager=kernel_manager,

voila/requirehandler.py

@@ -0,0 +1,85 @@
+import requests
+import logging
+import tornado.web
+import os
+
+from jupyter_server.base.handlers import JupyterHandler
+from jupyter_core.paths import (
+    jupyter_data_dir, jupyter_config_path, jupyter_path,
+    SYSTEM_JUPYTER_PATH, ENV_JUPYTER_PATH,
+)
+
+logger = logging.getLogger('Voila.require')
+
+whitelist = ['jupyter-leaflet', 'ipyvolume', 'bqplot', 'threejs']
+
+
+class RequireHandler(JupyterHandler):
+    cdn = 'https://unpkg.com/{module}@{version}/dist/index.js'
+
+    def initialize(self, cache_directories=None):
+        self.cache_directories = cache_directories
+        if self.cache_directories is None:
+            self.cache_directories = [os.path.join(k, 'voila_cache') for k in [ENV_JUPYTER_PATH[0], jupyter_data_dir()]]
+            logging.info('Using %r for caching directories', self.cache_directories)
+
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def get(self, path=None):
+        if path:
+            path = path.strip('/')  # remove leading /
+        if '@' not in path:
+            raise tornado.web.HTTPError(500)
+        module, version = path.rsplit('@', 1)
+        if module not in whitelist:
+            logger.error('Module %r not in whitelist, will not cache', module)
+            raise tornado.web.HTTPError(404)
+
+        url = self.cdn.format(module=module, version=version)
+        content = self.get_from_cache(module, version)
+        if not content:
+            logger.info('Request %s', url)
+            response = requests.get(url)
+            if response.ok:
+                self.put_in_cache(module, version, response.text)
+                content = response.text
+            else:
+                logger.error('Could not get: %r', path)
+                raise tornado.web.HTTPError(500)
+
+        self.set_header('Content-Type', 'text/javascript')
+        self.write(content)
+
+    def get_module_path(self, module, version):
+        return '{module}/{version}'.format(module=module, version=version)
+
+    def get_from_cache(self, module, version):
+        path = self.get_module_path(module, version)
+        for directory_path in self.cache_directories:
+            cache_path = os.path.join(directory_path, path)
+            try:
+                logger.info('Try opening cache file: %s', cache_path)
+                with open(cache_path) as f:
+                    logger.info('Found cache file: %s', cache_path)
+                    return f.read()
+            except FileNotFoundError:
+                pass
+
+    def put_in_cache(self, module, version, value):
+        path = self.get_module_path(module, version)
+        for directory_path in self.cache_directories:
+            cache_path = os.path.join(directory_path, path)
+            directory_path = os.path.dirname(cache_path)
+            if not os.path.exists(directory_path):
+                try:
+                    os.makedirs(directory_path)
+                except:
+                    pass
+            try:
+                logger.info('Try writing cache file: %s', cache_path)
+                with open(cache_path, 'w') as f:
+                    f.write(value)
+                    logger.info('Wrote cache file: %s', cache_path)
+                    return
+            except FileNotFoundError:
+                logger.info('Failed writing cache file: %s', cache_path)

voila/server_extension.py

@@ -1,3 +1,4 @@
+import logging
 import os
 import gettext
 from pathlib import Path
@@ -14,6 +15,7 @@
 from .treehandler import VoilaTreeHandler
 from .watchdog import WatchDogHandler
 
+logger = logging.getLogger('Voila.server_extension')
 
 def load_jupyter_server_extension(server_app):
     web_app = server_app.web_app
@@ -34,4 +36,6 @@ def load_jupyter_server_extension(server_app):
         (url_path_join(web_app.settings['base_url'], '/voila/static/(.*)'),  tornado.web.StaticFileHandler,
             {'path': str(STATIC_ROOT)})
 
-    ])
+    ])
+    voila_root = web_app.settings['base_url'] + 'voila'
+    server_app.log.info('Voila extension running at %s', voila_root)

voila/static/main.js

@@ -9,7 +9,10 @@ Array.prototype.forEach.call(scripts, (script) => {
 })
 
 requirejs.config({
-    baseUrl: '/voila/static/dist'
+    baseUrl: '/voila/require/',
+    paths: {
+        'libwidgets': '/voila/static/dist/libwidgets'
+    }
 })
 
 require(['libwidgets'], function(lib) {