Merge pull request #4735 from minrk/better-errors

add some HTML error pages

IPython/html/base/handlers.py

@@ -25,7 +25,13 @@
 import stat
 import sys
 import traceback
+try:
+    # py3
+    from http.client import responses
+except ImportError:
+    from httplib import responses
 
+from jinja2 import TemplateNotFound
 from tornado import web
 
 try:
@@ -46,14 +52,7 @@
 #-----------------------------------------------------------------------------
 non_alphanum = re.compile(r'[^A-Za-z0-9]')
 
-class RequestHandler(web.RequestHandler):
-    """RequestHandler with default variable setting."""
-
-    def render(*args, **kwargs):
-        kwargs.setdefault('message', '')
-        return web.RequestHandler.render(*args, **kwargs)
-
-class AuthenticatedHandler(RequestHandler):
+class AuthenticatedHandler(web.RequestHandler):
     """A RequestHandler with an authenticated user."""
 
     def clear_login_cookie(self):
@@ -212,6 +211,45 @@ def get_json_body(self):
             raise web.HTTPError(400, u'Invalid JSON in body of request')
         return model
 
+    def get_error_html(self, status_code, **kwargs):
+        """render custom error pages"""
+        exception = kwargs.get('exception')
+        message = ''
+        status_message = responses.get(status_code, 'Unknown HTTP Error')
+        if exception:
+            # get the custom message, if defined
+            try:
+                message = exception.log_message % exception.args
+            except Exception:
+                pass
+
+            # construct the custom reason, if defined
+            reason = getattr(exception, 'reason', '')
+            if reason:
+                status_message = reason
+
+        # build template namespace
+        ns = dict(
+            status_code=status_code,
+            status_message=status_message,
+            message=message,
+            exception=exception,
+        )
+
+        # render the template
+        try:
+            html = self.render_template('%s.html' % status_code, **ns)
+        except TemplateNotFound:
+            self.log.debug("No template for %d", status_code)
+            html = self.render_template('error.html', **ns)
+        return html
+
+
+class Template404(IPythonHandler):
+    """Render our 404 template"""
+    def prepare(self):
+        raise web.HTTPError(404)
+
 
 class AuthenticatedFileHandler(IPythonHandler, web.StaticFileHandler):
     """static files should only be accessible when logged in"""

IPython/html/nbconvert/handlers.py

@@ -6,7 +6,7 @@
 
 from ..base.handlers import IPythonHandler, notebook_path_regex
 from IPython.nbformat.current import to_notebook_json
-from IPython.nbconvert.exporters.export import exporter_map
+
 from IPython.utils import tz
 from IPython.utils.py3compat import cast_bytes
 
@@ -47,13 +47,33 @@ def respond_zip(handler, name, output, resources):
     handler.finish(buffer.getvalue())
     return True
 
+def get_exporter(format, **kwargs):
+    """get an exporter, raising appropriate errors"""
+    # if this fails, will raise 500
+    try:
+        from IPython.nbconvert.exporters.export import exporter_map
+    except ImportError as e:
+        raise web.HTTPError(500, "Could not import nbconvert: %s" % e)
+
+    try:
+        Exporter = exporter_map[format]
+    except KeyError:
+        # should this be 400?
+        raise web.HTTPError(404, u"No exporter for format: %s" % format)
+
+    try:
+        return Exporter(**kwargs)
+    except Exception as e:
+        raise web.HTTPError(500, "Could not construct Exporter: %s" % e)
+
 class NbconvertFileHandler(IPythonHandler):
 
     SUPPORTED_METHODS = ('GET',)
 
     @web.authenticated
     def get(self, format, path='', name=None):
-        exporter = exporter_map[format](config=self.config)
+
+        exporter = get_exporter(format, config=self.config)
 
         path = path.strip('/')
         os_path = self.notebook_manager.get_os_path(name, path)
@@ -62,8 +82,11 @@ def get(self, format, path='', name=None):
 
         info = os.stat(os_path)
         self.set_header('Last-Modified', tz.utcfromtimestamp(info.st_mtime))
-
-        output, resources = exporter.from_filename(os_path)
+
+        try:
+            output, resources = exporter.from_filename(os_path)
+        except Exception as e:
+            raise web.HTTPError(500, "nbconvert failed: %s" % e)
 
         if respond_zip(self, name, output, resources):
             return
@@ -86,12 +109,15 @@ class NbconvertPostHandler(IPythonHandler):
 
     @web.authenticated 
     def post(self, format):
-        exporter = exporter_map[format](config=self.config)
+        exporter = get_exporter(format, config=self.config)
 
         model = self.get_json_body()
         nbnode = to_notebook_json(model['content'])
-
-        output, resources = exporter.from_notebook_node(nbnode)
+
+        try:
+            output, resources = exporter.from_notebook_node(nbnode)
+        except Exception as e:
+            raise web.HTTPError(500, "nbconvert failed: %s" % e)
 
         if respond_zip(self, nbnode.metadata.name, output, resources):
             return

IPython/html/notebookapp.py

@@ -61,6 +61,7 @@
 
 # Our own libraries
 from IPython.html import DEFAULT_STATIC_FILES_PATH
+from .base.handlers import Template404
 
 from .services.kernels.kernelmanager import MappingKernelManager
 from .services.notebooks.nbmanager import NotebookManager
@@ -208,6 +209,8 @@ def init_handlers(self, settings):
             pattern = url_path_join(settings['base_project_url'], handler[0])
             new_handler = tuple([pattern] + list(handler[1:]))
             new_handlers.append(new_handler)
+        # add 404 on the end, which will catch everything that falls through
+        new_handlers.append((r'(.*)', Template404))
         return new_handlers
 
 

IPython/html/services/nbconvert/handlers.py

@@ -3,14 +3,17 @@
 from tornado import web
 
 from ...base.handlers import IPythonHandler, json_errors
-from IPython.nbconvert.exporters.export import exporter_map
 
 class NbconvertRootHandler(IPythonHandler):
     SUPPORTED_METHODS = ('GET',)
 
     @web.authenticated
     @json_errors
     def get(self):
+        try:
+            from IPython.nbconvert.exporters.export import exporter_map
+        except ImportError as e:
+            raise web.HTTPError(500, "Could not import nbconvert: %s" % e)
         res = {}
         for format, exporter in exporter_map.items():
             res[format] = info = {}

IPython/html/static/base/less/error.less

@@ -0,0 +1,20 @@
+div.error {
+  margin: 2em;
+  text-align: center;
+}
+
+div.error > h1 {
+    font-size: 500%;
+    line-height: normal;
+}
+
+div.error > p {
+    font-size: 200%;
+    line-height: normal;
+}
+
+div.traceback-wrapper {
+    text-align: left;
+    max-width: 800px;
+    margin: auto;
+}

IPython/html/static/base/less/style.less

@@ -1,4 +1,4 @@
 @import "variables.less";
 @import "mixins.less";
 @import "flexbox.less";
-
+@import "error.less";

IPython/html/static/style/ipython.min.css

@@ -18,6 +18,10 @@
 .start{-webkit-box-pack:start;-moz-box-pack:start;box-pack:start;}
 .end{-webkit-box-pack:end;-moz-box-pack:end;box-pack:end;}
 .center{-webkit-box-pack:center;-moz-box-pack:center;box-pack:center;}
+div.error{margin:2em;text-align:center;}
+div.error>h1{font-size:500%;line-height:normal;}
+div.error>p{font-size:200%;line-height:normal;}
+div.traceback-wrapper{text-align:left;max-width:800px;margin:auto;}
 .center-nav{display:inline-block;margin-bottom:-4px;}
 .alternate_upload{background-color:none;display:inline;}
 .alternate_upload.form{padding:0;margin:0;}

IPython/html/templates/404.html

@@ -0,0 +1,5 @@
+{% extends "error.html" %}
+{% block error_detail %}
+<p>You are requesting a page that does not exist!</p>
+{% endblock %}
+

IPython/html/templates/error.html

@@ -0,0 +1,31 @@
+{% extends "page.html" %}
+
+{% block login_widget %}
+{% endblock %}
+
+{% block stylesheet %}
+{{super()}}
+<style type="text/css">
+/* disable initial hide */
+div#header, div#site {
+    display: block;
+}
+</style>
+{% endblock %}
+{% block site %}
+
+<div class="error">
+    {% block h1_error %}
+    <h1>{{status_code}} : {{status_message}}</h1>
+    {% endblock h1_error %}
+    {% block error_detail %}
+    {% if message %}
+    <p>The error was:</p>
+    <div class="traceback-wrapper">
+    <pre class="traceback">{{message}}</pre>
+    </div>
+    {% endif %}
+    {% endblock %}
+</header>
+
+{% endblock %}

IPython/nbconvert/exporters/templateexporter.py

@@ -19,8 +19,8 @@
 # Stdlib imports
 import os
 
-# other libs/dependencies
-from jinja2 import Environment, FileSystemLoader, ChoiceLoader, TemplateNotFound
+# other libs/dependencies are imported at runtime
+# to move ImportErrors to runtime when the requirement is actually needed
 
 # IPython imports
 from IPython.utils.traitlets import MetaHasTraits, Unicode, List, Dict, Any
@@ -164,6 +164,8 @@ def _load_template(self):
         
         This is triggered by various trait changes that would change the template.
         """
+        from jinja2 import TemplateNotFound
+
         if self.template is not None:
             return
         # called too early, do nothing
@@ -274,6 +276,7 @@ def _init_environment(self, extra_loaders=None):
         """
         Create the Jinja templating environment.
         """
+        from jinja2 import Environment, ChoiceLoader, FileSystemLoader
         here = os.path.dirname(os.path.realpath(__file__))
         loaders = []
         if extra_loaders:

IPython/nbconvert/filters/highlight.py

@@ -14,14 +14,11 @@
 # Imports
 #-----------------------------------------------------------------------------
 
-from pygments import highlight as pygements_highlight
-from pygments.lexers import get_lexer_by_name
-from pygments.formatters import HtmlFormatter
-from pygments.formatters import LatexFormatter
-
+# pygments must not be imported at the module level
+# because errors should be raised at runtime if it's actually needed,
+# not import time, when it may not be needed.
 
 # Our own imports
-from IPython.nbconvert.utils.lexers import IPythonLexer
 from IPython.nbconvert.utils.base import NbConvertBase
 
 #-----------------------------------------------------------------------------
@@ -55,10 +52,11 @@ def __call__(self, source, language=None, metadata=None):
         metadata : NotebookNode cell metadata
             metadata of the cell to highlight
         """
+        from pygments.formatters import HtmlFormatter
         if not language:
             language=self.default_language
 
-        return _pygment_highlight(source, HtmlFormatter(), language, metadata)
+        return _pygments_highlight(source, HtmlFormatter(), language, metadata)
 
 
 class Highlight2Latex(NbConvertBase):
@@ -78,10 +76,11 @@ def __call__(self, source, language=None, metadata=None, strip_verbatim=False):
         strip_verbatim : bool
             remove the Verbatim environment that pygments provides by default
         """
+        from pygments.formatters import LatexFormatter
         if not language:
             language=self.default_language
 
-        latex = _pygment_highlight(source, LatexFormatter(), language, metadata)
+        latex = _pygments_highlight(source, LatexFormatter(), language, metadata)
         if strip_verbatim:
             latex = latex.replace(r'\begin{Verbatim}[commandchars=\\\{\}]' + '\n', '')
             return latex.replace('\n\\end{Verbatim}\n', '')
@@ -90,7 +89,7 @@ def __call__(self, source, language=None, metadata=None, strip_verbatim=False):
 
 
 
-def _pygment_highlight(source, output_formatter, language='ipython', metadata=None):
+def _pygments_highlight(source, output_formatter, language='ipython', metadata=None):
     """
     Return a syntax-highlighted version of the input source
 
@@ -104,6 +103,9 @@ def _pygment_highlight(source, output_formatter, language='ipython', metadata=No
     metadata : NotebookNode cell metadata
         metadata of the cell to highlight
     """
+    from pygments import highlight
+    from pygments.lexers import get_lexer_by_name
+    from IPython.nbconvert.utils.lexers import IPythonLexer
 
     # If the cell uses a magic extension language,
     # use the magic language instead.
@@ -118,4 +120,4 @@ def _pygment_highlight(source, output_formatter, language='ipython', metadata=No
     else:
         lexer = get_lexer_by_name(language, stripall=True)
 
-    return pygements_highlight(source, lexer, output_formatter)
+    return highlight(source, lexer, output_formatter)

IPython/nbconvert/preprocessors/csshtmlheader.py

@@ -15,8 +15,6 @@
 import os
 import io
 
-from pygments.formatters import HtmlFormatter
-
 from IPython.utils import path
 
 from .base import Preprocessor
@@ -83,6 +81,7 @@ def _regen_header(self):
         Fills self.header with lines of CSS extracted from IPython 
         and Pygments.
         """
+        from pygments.formatters import HtmlFormatter
 
         #Clear existing header.
         header = []