Heroku This site can’t be reached (DNS_PROBE_FINISHED_NXDOMAIN) - node.js

Some of my personal apps and my professional apps on Heroku are not accessible.
They don't have a custom domain linked, so I access them via http://.herokuapp.com
Most of the time, they work great, but often I receive following response from my browser
This site can’t be reached
<myapp>.herokuapp.com’s server IP address could not be found.
DNS_PROBE_FINISHED_NXDOMAIN
The app is up and running. It does not crash (as I haven't made any changes to it in a while).
I have tried restarting all dynos, to which the log says that the app is up and running and the db is connected.
Heroku is also not reporting any of their services to being down either.
How can I resolve this issue?
I have read a similar question, but the only result coming from it was that Heroku was temporarily down. So please don't link that one again.
Update
Without any of my interference, the application can be reached again on Heroku. How is this possible if Heroku says that there were no problems with their app platforms?
And more important: is there a way to defend against this?

Related

IIS/IISnode - not serving files (no error messages)

I have a Node project running on a Windows server using IISNode on a Windows virtual machine.
Everything worked fine up until a few days ago when the VM underwent a Windows update, and now the site isn't serving any files.
When I start the server, there is no indication of anything being wrong, but when I go to the URL, I get the message:
www.mydomain.com didn't send any data
ERR_EMPTY_RESPONSE
Initially, when I was checking all the settings, I noticed that when I clicked 'Test Settings' under basic settings, that there was an authorization failure saying it cannot verify access to the source code directory.
But when I changed it to connect as specific user instead of application user, the error went away but the above issue was unchanged.
This makes me think it could be a permissions issue, but I've granted permission to the App Pool, IIS_IUSRS and IUSR, so I could be wrong.
I've tried multiple solutions on StackOverflow, including this highly rated one with no luck.
Any help would be appreciated.
Annoyingly, I found the answer a few hours after placing the bounty.
The problem was that it didn't have a static IP address, so when the VM was updated it was on DHCP and so was allocated a new IP, hence the website stopped working.

net::ERR_CONNECTION_REFUSED when moving app from local machine to remote server

Had a look around at some other threads and there doesn't seem to be someone with this exact problem.
The problem is that I have made a webapp that works fine when hosting it locally. On the app there is a button that causes a request to be sent to my server and it performs as expected on localhost:3000 but when I host it remotely on a linux box purchased from digital ocean the site loads but the when the button is pressed I see
net::ERR_CONNECTION_REFUSED
in the console.
I'm not sure how useful it would be to post code so I will leave that out unless requested. I'm hoping this is due to some server configuration issue?
Further info:
This is a node application on a server running ubuntu. To run the application I use and keep it running I use PM2.
Thanks in advance.

Azure Kudu Debug Console not accessible because of DNS error

I created a new Azure Web App (web site) on the path https://todoangular1-b-nschou.azurewebsites.net and I tried to access the Kudu Debug Console by inserting 'scm' between the application name and the domain name. Like this:
https://todoangular1-b-nschou.scm.azurewebsites.net/
However, the site is not available.
Some more research showed that the error was caused by a failing DNS resolution. I then added an entry to my hosts file pointing todoangular1-b-nschou.scm.azurewebsites.net to the same ip-address as todoangular1-b-nschou.azurewebsites.net and suddenly it worked.
My own conclusion is that the Azure platform did not properly add the new DNS-name under the scm.azurewebsites.net zone. Did anyone else experience this odd behavior?
What probably happened is that there was a small delay in DNS propagation. But if you try hitting the site before that, you would then be affected by DNS negative caching on your machine, which can last a little while. My guess is that during that time, if you had tried to access it from a different machine that didn't have the negative caching, it would have worked (and it works fine now).

Azure Mobile Services on Local IIS rather than IIS Express

OK, I've created an Azure Mobile Services project in Visual Studio 2013.
I run it up as-is, then in the browser I test it by adding a todo item via the simple browser app that seems to get baked into these service projects. It gives me a '201 success' message - brilliant.
I then convert the project from IIS Express to Local IIS as the web host, recompile and try again, and although I get the same smiley face app telling me that everything is OK, when I try and add a todo item I get a 404 error. This is contrary to the Microsoft article that gives these instructions, which clearly says I am able to choose either IIS Express or Local IIS when setting up the project.
My guess is that web.config is missing something when this project runs on the local IIS server.
I'm hoping someone already has a solution before I spend hours trying to work out how to configure IIS for this type of project.
I've already wasted a load of time working through loads of bugs and gotchas with Azure Mobile, and I'm starting to run out of steam - so I'm hoping someone can help me before I go and grab an account at Parse.com
Many thanks in anticipation.
Dean
The easiest approach for your situation might be to just deploy to the cloud, and use that service for your testing. Visual Studio 2013 Update 2 makes it easy to deploy your app and connect to it for remote debugging. It is a little slower than using a local instance, but you are also assured that there will be no surprises when you eventually go live (since you are live the whole time).
That said, we will investigate the issue you are seeing with using IIS directly. Some things you might want to try on your own:
Verify that you can view the web side from your Mac's browser, to make sure that the firewall is letting the requests through.
Try using the "Getting Starting" link from the smiley-face page, to see if the REST endpoints are behaving correctly.

IIS ApplicationPoolIdentity 503 error

I've recently ported to a different hosting company (VDS), and on the new server, installed IIS 7.5 Express, latest versions of PHP and MySQL.
I then copied the files from the old server to new server (NOTHING beyond the content of the folders of my websites, so no config files or anything except the web.configs in the sites themselves), set-up websites. I've tried to visit a website, and I got a 503 Service Unavailable message, tried both remotely and locally at the server, no change.
Tried on every site, even on Default Web Site, and no change: still 503.
I've checked the permissions to the folders of the websites (and all the children), and both my account, Network Service, Administrators have effectively full control of all the contents.
All the apps run in DefaultAppPool, which runs under ApplicationPoolIdentity. Tried creating a new app pool, moving sites there, no luck, tried setting "Load User Profile" to False in pool settings (read it here HTTP Error 503 on IIS 7.5 after SP Install), no change.
The event viewer in an extremely detailed way says:
"A process serving application pool 'DefaultAppPool' terminated unexpectedly. The process id was '2356'. The process exit code was '0xfffffffe'."
and nothing else. Five times of this error, and the pool is shut down due to rapid protection. I restart the pool, try again, nothing changes. No matter I'm trying to get an .aspx, .php, or static content. Here is the most weird part: when I set the app pool to run under LocalSystem, it works. No problem. But everything else fails.
I've checked the website folders about ten times, changed, erased, re-added rights etc tried everything but no change. It's as if there is another file that I'm forgetting to check that the pool's user is unable to access. But the event viewer does not help me. This started with the new server and I tried after installing everything, so I can't tell after what this started happening. I obviously won't be running under LocalSystem. Even my own user, Administrator, doesn't work.
The only identity that works is LocalSystem. My user, LocalService, NetworkService, ApplicationPoolIdentity all fail the same way. I'm going crazy, I'm 99% sure this is a user-rights issue. But all the website files are accessible, and I haven't changed anything in the system32 inetconfig or anywhere.
Ok, found my own answer again.
The process w3wp.exe runs under the DefaultAppPool user, not NETWORK SERVICE. I don't know why it doesn't run under NETWORK SERVICE, but after some research it turned out that the process needed access to C:\Windows\System32\inetsrv\config\schema and giving NETWORK SERVICE access didn't change anything. I've by coincidence found somewhere about the DefaultAppPool user, gave read permissions, and by starting the pool, all my websites started working perfectly. Quite weird, I always thought that the IIS processes ran under NETWORK SERVICE by default, and I'm sure that I haven't changed any setting.
Try running below commands with some changes
appcmd set apppool /apppool.name: <YourAppPoolHavingIssuesHere> /managedRuntieVersion:v<.net Framework version here>

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