I am backing a web app with a Flask API that returns custom error codes. The API runs through Apache and the WSGI module, in daemon mode.
I included a WSGIErrorOverride Off instruction in the Apache conf file for the API (which is supposed to be the default but I included it anyway).
Yet anytime my Flask app returns a custom error code (they work when I run the app using the built-in server), Apache sends an error 500. How can I prevent that?
Thanks to comments by duskwuff and Graham Dumpleton, I found that the problem doesn't come from Apache WSGI but from my Flask app.
More precisely, I was using the Flask-RESTful package, which is in charge, among other things, of transforming my views' return values into actual responses.
When those views are decorated (here with an equivalent of #login_required), those decorators are called by the Flask-RESTful package itself, and when an exception is thrown, something goes wrong.
For some reason, my app returns the custom error when I run the built-in server and an error 500 when I run it over Apache. Not quite sure why yet, I'm guessing Flask-RESTful is doing something that is not WSGI-compliant. I was on the verge of dropping it anyway for other reasons, so I'm OK with this solution.
Update: it looks like the problem does indeed come from Flask-RESTful: https://github.com/flask-restful/flask-restful/issues/372
Related
I have made a flask application at my local computer in the debugging mode and it runs all fine. But when it comes to production, the website gives me 500 or internal server error, which I have no idea what the bug is. I am fairly new to flask production and this has been stopping me from moving forward for quite a few days.
My questions are:
1> in my local development environment, one could always print things out. But how can I see those prints in the production stage?
2> Do I see them through Apache2 log? Where is Apache2 log?
For production, I actually followed the tutorials from pythonprogramming.net. Youtube link is here:
https://www.youtube.com/watch?v=qZNL4Ku1UQg&list=PLQVvvaa0QuDc_owjTbIY4rbgXOFkUYOUB&index=2
To use a very simple example, if the code imports a package which wasn't installed, where can we see the errors?
Thanks in advance.
I've tried to use to use try ... except block for every flask function. Whenever there is an exception, it can be return to the front-end. But what about other errors?
I found out:
Use logging module
Read apache2 log from /var/log/apache2
I am using a java raw HTTP client to connect to Shopify API (specifically, using Play Framework with the non-defualt sync driver which is actually the JDK's default driver).
My application usually manages to connect successfully and convert the temporary access token into a permanent one by calling the /admin/oauth/access_token endpoint.
However, sometimes I get this error result from the API:
Generic Error(400)
{"error":"invalid_request"}
I haven't been able to reproduce the issue with my test stores - I've tried installing a fresh store, reinstalling existing stores after uninstalling, I'm not sure why this call sometimes fail and how to debug it. The API call still continues to succeed for some stores using our application.
Some things that I am doing:
Even if the URL of the store is on a custom domain, I'm always using the https://foo.myshopfiy.com/admin/oauth/access_token URL and not the URL of the custom domain, to prevent a redirect.
I am always using an https URL and never an http one, again to prevent a redirect (we noticed a few issues with redirect with the Java HTTP client, so we aim to have zero redirects)
A thread I found about this error suggest possible problems with our SSL certificates, however I don't think this is my problem because some requests work for us, and the result of running openssl on our machine does't show any issues.
How should I proceed? Open a support ticket with Shopify?
FYI, I see that this specific problem only started yesterday on Feb 19 2013, so it might be a temporary issue.
FYI, the problem was caused by reusing a temporary access code.
Our fault - Shopify could have been more clear in their error message though.
We are running a Domino 8.5.3 and the server log is constantly issuing these errors:
HTTP JVM:
!err.PersistenceServiceResourceProvider.Errorwritingtopersistedcontenttor!
We have not been able to isloate it to a particular page. Eventually, the HTTP task will crash and we need to reboot the server and recompile all the databases on the server. We are using the CKEditor to generate the HTML content. You help would be most appreciated.
We used to get this exact error a lot which appeared to be caused by inline images uploaded via the CKEditor like Paul mentioned.
I don't know why but we fixed it by changing the directory domino uses for uploads via the
xsp property xsp.persistence.dir.xspupload (formally xsp.upload.directory)
changing it to something like c:\temp rather than the windows default made the problem go away. could have been a co-incidence but may have been something in windows interfering
I haven't seen that error before but it reads like it might be something to do with asking the server to make a lot of data available to the xpages between calls to the server- effectively, session and application scope data.
I'd like to know how to troubleshoot IIS URL Rewrite module and custom rewrite providers?
I am trying to do a POC on the URL Rewrite Module for our app. Our mappings are all in the database so I thought using the provider that comes as a sample. Got everything installed and configured, as instructed. Created the stored procedure as well. Now when I hit the alias URL I receive HTTP Error 500.50 - URL Rewrite Module Error. Here are the details about the error:
Module RewriteModule
Notification BeginRequest
Handler ExtensionlessUrlHandler-Integrated-4.0
Error Code 0x80070585
In SQL Profiler I see no calls to my stored procedure. The app pool is running under my account (admin rights). No errors in the event logs.
Are there any logs I could look into for more information on what's happening?
I got it working after two days of digging. The samples are good but not good enough: simply using supplied DLLs with supplied config entries doesn't work (for many reasons).
What I ended up doing was getting rid of the DLLs from samples and creating my own provider using the source code from samples and information from this article: Developing a Custom Rewrite Provider for URL Rewrite Module. Then IIS started loading my provider. But in order to make it work correctly I had to get deep understanding of module's config system.
So my answer to my own question -- don't relay on samples alone, they don't work out of the box. Instead, RTFM :) The best place to start is here: URL Rewrite Module Configuration Reference
I have created a web application in Apache Cocoon.This website is running properly but after every 3-4 days, it stops responding. It doesn't run until and unless, we restart the tomcat service. In the catalina.2011-05-09.log file, it shows following error:-
"May 9, 2011 3:17:34 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/webresources] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation."
I am not been able to understand the cause of this problem. Can someone suggest me how to resolve this issue?
You are using a library that is starting one or more threads and is not properly shutting them down or releasing other resources captured by the thread. This often happens with things like Apache HTTP components (I get this error with Http Components) and anything that uses separate threads internally. What libraries are you using in your Cocoon application?
It is telling you the issue:
[...] is still processing a request that has yet to finish
You need to find out what that request is/is going to. One easy way is to have something like PsiProbe installed.
Also, it's not a bad idea to restart Tomcat every night. It can help alleviate these kinds of issues until you find the root cause.