Add text and json fallback error handlers (#1937)

* Add text and json fallback error handlers

* Add tests and auto-detect error fallback type
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Adam Hopkins 2020-09-30 15:11:27 +03:00 committed by GitHub
parent 0c4a9b1dce
commit 066df2c142
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4 changed files with 397 additions and 97 deletions

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@ -32,6 +32,7 @@ DEFAULT_CONFIG = {
"REAL_IP_HEADER": None,
"PROXIES_COUNT": None,
"FORWARDED_FOR_HEADER": "X-Forwarded-For",
"FALLBACK_ERROR_FORMAT": "html",
}

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@ -1,13 +1,283 @@
import sys
import typing as t
from functools import partial
from traceback import extract_tb
from sanic.exceptions import SanicException
from sanic.exceptions import InvalidUsage, SanicException
from sanic.helpers import STATUS_CODES
from sanic.response import html
from sanic.request import Request
from sanic.response import HTTPResponse, html, json, text
# Here, There Be Dragons (custom HTML formatting to follow)
try:
from ujson import dumps
dumps = partial(dumps, escape_forward_slashes=False)
except ImportError: # noqa
from json import dumps # type: ignore
FALLBACK_TEXT = (
"The server encountered an internal error and "
"cannot complete your request."
)
FALLBACK_STATUS = 500
class BaseRenderer:
def __init__(self, request, exception, debug):
self.request = request
self.exception = exception
self.debug = debug
@property
def headers(self):
if isinstance(self.exception, SanicException):
return getattr(self.exception, "headers", {})
return {}
@property
def status(self):
if isinstance(self.exception, SanicException):
return getattr(self.exception, "status_code", FALLBACK_STATUS)
return FALLBACK_STATUS
@property
def text(self):
if self.debug or isinstance(self.exception, SanicException):
return str(self.exception)
return FALLBACK_TEXT
@property
def title(self):
status_text = STATUS_CODES.get(self.status, b"Error Occurred").decode()
return f"{self.status}{status_text}"
def render(self):
output = (
self.full
if self.debug and not getattr(self.exception, "quiet", False)
else self.minimal
)
return output()
def minimal(self): # noqa
raise NotImplementedError
def full(self): # noqa
raise NotImplementedError
class HTMLRenderer(BaseRenderer):
TRACEBACK_STYLE = """
html { font-family: sans-serif }
h2 { color: #888; }
.tb-wrapper p { margin: 0 }
.frame-border { margin: 1rem }
.frame-line > * { padding: 0.3rem 0.6rem }
.frame-line { margin-bottom: 0.3rem }
.frame-code { font-size: 16px; padding-left: 4ch }
.tb-wrapper { border: 1px solid #eee }
.tb-header { background: #eee; padding: 0.3rem; font-weight: bold }
.frame-descriptor { background: #e2eafb; font-size: 14px }
"""
TRACEBACK_WRAPPER_HTML = (
"<div class=tb-header>{exc_name}: {exc_value}</div>"
"<div class=tb-wrapper>{frame_html}</div>"
)
TRACEBACK_BORDER = (
"<div class=frame-border>"
"The above exception was the direct cause of the following exception:"
"</div>"
)
TRACEBACK_LINE_HTML = (
"<div class=frame-line>"
"<p class=frame-descriptor>"
"File {0.filename}, line <i>{0.lineno}</i>, "
"in <code><b>{0.name}</b></code>"
"<p class=frame-code><code>{0.line}</code>"
"</div>"
)
OUTPUT_HTML = (
"<!DOCTYPE html><html lang=en>"
"<meta charset=UTF-8><title>{title}</title>\n"
"<style>{style}</style>\n"
"<h1>{title}</h1><p>{text}\n"
"{body}"
)
def full(self):
return html(
self.OUTPUT_HTML.format(
title=self.title,
text=self.text,
style=self.TRACEBACK_STYLE,
body=self._generate_body(),
),
status=self.status,
)
def minimal(self):
return html(
self.OUTPUT_HTML.format(
title=self.title,
text=self.text,
style=self.TRACEBACK_STYLE,
body="",
),
status=self.status,
headers=self.headers,
)
@property
def text(self):
return escape(super().text)
@property
def title(self):
return escape(f"⚠️ {super().title}")
def _generate_body(self):
_, exc_value, __ = sys.exc_info()
exceptions = []
while exc_value:
exceptions.append(self._format_exc(exc_value))
exc_value = exc_value.__cause__
traceback_html = self.TRACEBACK_BORDER.join(reversed(exceptions))
appname = escape(self.request.app.name)
name = escape(self.exception.__class__.__name__)
value = escape(self.exception)
path = escape(self.request.path)
lines = [
f"<h2>Traceback of {appname} (most recent call last):</h2>",
f"{traceback_html}",
"<div class=summary><p>",
f"<b>{name}: {value}</b> while handling path <code>{path}</code>",
"</div>",
]
return "\n".join(lines)
def _format_exc(self, exc):
frames = extract_tb(exc.__traceback__)
frame_html = "".join(
self.TRACEBACK_LINE_HTML.format(frame) for frame in frames
)
return self.TRACEBACK_WRAPPER_HTML.format(
exc_name=escape(exc.__class__.__name__),
exc_value=escape(exc),
frame_html=frame_html,
)
class TextRenderer(BaseRenderer):
OUTPUT_TEXT = "{title}\n{bar}\n{text}\n\n{body}"
SPACER = " "
def full(self):
return text(
self.OUTPUT_TEXT.format(
title=self.title,
text=self.text,
bar=("=" * len(self.title)),
body=self._generate_body(),
),
status=self.status,
)
def minimal(self):
return text(
self.OUTPUT_TEXT.format(
title=self.title,
text=self.text,
bar=("=" * len(self.title)),
body="",
),
status=self.status,
headers=self.headers,
)
@property
def title(self):
return f"⚠️ {super().title}"
def _generate_body(self):
_, exc_value, __ = sys.exc_info()
exceptions = []
# traceback_html = self.TRACEBACK_BORDER.join(reversed(exceptions))
lines = [
f"{self.exception.__class__.__name__}: {self.exception} while "
f"handling path {self.request.path}",
f"Traceback of {self.request.app.name} (most recent call last):\n",
]
while exc_value:
exceptions.append(self._format_exc(exc_value))
exc_value = exc_value.__cause__
return "\n".join(lines + exceptions[::-1])
def _format_exc(self, exc):
frames = "\n\n".join(
[
f"{self.SPACER * 2}File {frame.filename}, "
f"line {frame.lineno}, in "
f"{frame.name}\n{self.SPACER * 2}{frame.line}"
for frame in extract_tb(exc.__traceback__)
]
)
return f"{self.SPACER}{exc.__class__.__name__}: {exc}\n{frames}"
class JSONRenderer(BaseRenderer):
def full(self):
output = self._generate_output(full=True)
return json(output, status=self.status, dumps=dumps)
def minimal(self):
output = self._generate_output(full=False)
return json(output, status=self.status, dumps=dumps)
def _generate_output(self, *, full):
output = {
"description": self.title,
"status": self.status,
"message": self.text,
}
if full:
_, exc_value, __ = sys.exc_info()
exceptions = []
while exc_value:
exceptions.append(
{
"type": exc_value.__class__.__name__,
"exception": str(exc_value),
"frames": [
{
"file": frame.filename,
"line": frame.lineno,
"name": frame.name,
"src": frame.line,
}
for frame in extract_tb(exc_value.__traceback__)
],
}
)
exc_value = exc_value.__cause__
output["path"] = self.request.path
output["args"] = self.request.args
output["exceptions"] = exceptions[::-1]
return output
@property
def title(self):
return STATUS_CODES.get(self.status, b"Error Occurred").decode()
def escape(text):
@ -15,103 +285,46 @@ def escape(text):
return f"{text}".replace("&", "&amp;").replace("<", "&lt;")
def exception_response(request, exception, debug):
status = 500
text = (
"The server encountered an internal error "
"and cannot complete your request."
)
RENDERERS_BY_CONFIG = {
"html": HTMLRenderer,
"json": JSONRenderer,
"text": TextRenderer,
}
headers = {}
if isinstance(exception, SanicException):
text = f"{exception}"
status = getattr(exception, "status_code", status)
headers = getattr(exception, "headers", headers)
elif debug:
text = f"{exception}"
status_text = STATUS_CODES.get(status, b"Error Occurred").decode()
title = escape(f"{status}{status_text}")
text = escape(text)
if debug and not getattr(exception, "quiet", False):
return html(
f"<!DOCTYPE html><meta charset=UTF-8><title>{title}</title>"
f"<style>{TRACEBACK_STYLE}</style>\n"
f"<h1>⚠️ {title}</h1><p>{text}\n"
f"{_render_traceback_html(request, exception)}",
status=status,
)
# Keeping it minimal with trailing newline for pretty curl/console output
return html(
f"<!DOCTYPE html><meta charset=UTF-8><title>{title}</title>"
"<style>html { font-family: sans-serif }</style>\n"
f"<h1>⚠️ {title}</h1><p>{text}\n",
status=status,
headers=headers,
)
RENDERERS_BY_CONTENT_TYPE = {
"multipart/form-data": HTMLRenderer,
"application/json": JSONRenderer,
"text/plain": TextRenderer,
}
def _render_exception(exception):
frames = extract_tb(exception.__traceback__)
frame_html = "".join(TRACEBACK_LINE_HTML.format(frame) for frame in frames)
return TRACEBACK_WRAPPER_HTML.format(
exc_name=escape(exception.__class__.__name__),
exc_value=escape(exception),
frame_html=frame_html,
)
def exception_response(
request: Request,
exception: Exception,
debug: bool,
renderer: t.Type[t.Optional[BaseRenderer]] = None,
) -> HTTPResponse:
"""Render a response for the default FALLBACK exception handler"""
if not renderer:
renderer = HTMLRenderer
def _render_traceback_html(request, exception):
exc_type, exc_value, tb = sys.exc_info()
exceptions = []
while exc_value:
exceptions.append(_render_exception(exc_value))
exc_value = exc_value.__cause__
if request:
if request.app.config.FALLBACK_ERROR_FORMAT == "auto":
try:
renderer = JSONRenderer if request.json else HTMLRenderer
except InvalidUsage:
renderer = HTMLRenderer
traceback_html = TRACEBACK_BORDER.join(reversed(exceptions))
appname = escape(request.app.name)
name = escape(exception.__class__.__name__)
value = escape(exception)
path = escape(request.path)
return (
f"<h2>Traceback of {appname} (most recent call last):</h2>"
f"{traceback_html}"
"<div class=summary><p>"
f"<b>{name}: {value}</b> while handling path <code>{path}</code>"
)
content_type, *_ = request.headers.get(
"content-type", ""
).split(";")
renderer = RENDERERS_BY_CONTENT_TYPE.get(
content_type, renderer
)
else:
render_format = request.app.config.FALLBACK_ERROR_FORMAT
renderer = RENDERERS_BY_CONFIG.get(render_format, renderer)
TRACEBACK_STYLE = """
html { font-family: sans-serif }
h2 { color: #888; }
.tb-wrapper p { margin: 0 }
.frame-border { margin: 1rem }
.frame-line > * { padding: 0.3rem 0.6rem }
.frame-line { margin-bottom: 0.3rem }
.frame-code { font-size: 16px; padding-left: 4ch }
.tb-wrapper { border: 1px solid #eee }
.tb-header { background: #eee; padding: 0.3rem; font-weight: bold }
.frame-descriptor { background: #e2eafb; font-size: 14px }
"""
TRACEBACK_WRAPPER_HTML = (
"<div class=tb-header>{exc_name}: {exc_value}</div>"
"<div class=tb-wrapper>{frame_html}</div>"
)
TRACEBACK_BORDER = (
"<div class=frame-border>"
"The above exception was the direct cause of the following exception:"
"</div>"
)
TRACEBACK_LINE_HTML = (
"<div class=frame-line>"
"<p class=frame-descriptor>"
"File {0.filename}, line <i>{0.lineno}</i>, "
"in <code><b>{0.name}</b></code>"
"<p class=frame-code><code>{0.line}</code>"
"</div>"
)
renderer = t.cast(t.Type[BaseRenderer], renderer)
return renderer(request, exception, debug).render()

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@ -126,7 +126,7 @@ def test_app_handle_request_handler_is_none(app, monkeypatch):
def handler(request):
return text("test")
request, response = app.test_client.get("/test")
_, response = app.test_client.get("/test")
assert (
"'None' was returned while requesting a handler from the router"

86
tests/test_errorpages.py Normal file
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@ -0,0 +1,86 @@
import pytest
from sanic import Sanic
from sanic.errorpages import exception_response
from sanic.exceptions import NotFound
from sanic.request import Request
from sanic.response import HTTPResponse
@pytest.fixture
def app():
app = Sanic("error_page_testing")
@app.route("/error", methods=["GET", "POST"])
def err(request):
raise Exception("something went wrong")
return app
@pytest.fixture
def fake_request(app):
return Request(b"/foobar", {}, "1.1", "GET", None, app)
@pytest.mark.parametrize(
"fallback,content_type, exception, status",
(
(None, "text/html; charset=utf-8", Exception, 500),
("html", "text/html; charset=utf-8", Exception, 500),
("auto", "text/html; charset=utf-8", Exception, 500),
("text", "text/plain; charset=utf-8", Exception, 500),
("json", "application/json", Exception, 500),
(None, "text/html; charset=utf-8", NotFound, 404),
("html", "text/html; charset=utf-8", NotFound, 404),
("auto", "text/html; charset=utf-8", NotFound, 404),
("text", "text/plain; charset=utf-8", NotFound, 404),
("json", "application/json", NotFound, 404),
),
)
def test_should_return_html_valid_setting(
fake_request, fallback, content_type, exception, status
):
if fallback:
fake_request.app.config.FALLBACK_ERROR_FORMAT = fallback
try:
raise exception("bad stuff")
except Exception as e:
response = exception_response(fake_request, e, True)
assert isinstance(response, HTTPResponse)
assert response.status == status
assert response.content_type == content_type
def test_auto_fallback_with_data(app):
app.config.FALLBACK_ERROR_FORMAT = "auto"
_, response = app.test_client.get("/error")
assert response.status == 500
assert response.content_type == "text/html; charset=utf-8"
_, response = app.test_client.post("/error", json={"foo": "bar"})
assert response.status == 500
assert response.content_type == "application/json"
_, response = app.test_client.post("/error", data={"foo": "bar"})
assert response.status == 500
assert response.content_type == "text/html; charset=utf-8"
def test_auto_fallback_with_content_type(app):
app.config.FALLBACK_ERROR_FORMAT = "auto"
_, response = app.test_client.get(
"/error", headers={"content-type": "application/json"}
)
assert response.status == 500
assert response.content_type == "application/json"
_, response = app.test_client.get(
"/error", headers={"content-type": "text/plain"}
)
assert response.status == 500
assert response.content_type == "text/plain; charset=utf-8"