I keep getting an error 503 on my health checks for my azure functions, it says error 503. Functions host is not running. It's very inconsistent and only happens once every few days, I'm on the consumption plan but looking at whether a premium plan would fix the issue.
In Azure Functions, 503 service unavailable causes for the reasons like:
Function host is down/restarting
Platform issue due to the backend server not running/ allocated
Memory leak/issue from the code causing the backend server to return 503
To get some insights about the function host related issues, take a look into the "Diagnose and solve problems" blade in the Function app and select the "Function app down or reporting" detector. This detector will show all the diagnostic information about the function app and its infrastructure.
503 service unavailable comes sometimes when the function takes more than 5 minutes to return an HTTP response in consumption plan. Regardless of the function app timeout setting, 230 seconds is the maximum amount of time that an HTTP triggered function can take to respond to a request.
For longer processing times, use Azure Durable Functions async pattern. Refer to this link.
We should not change the app settings frequently in the production environment. If you update the app settings, the app will be restarted. In this cases, you will get 503 error. In order to avoid this, you can use the slot feature
Function host is not running
This issue happens due to invalid host.json. To diagnose, it's best to look at the function host logs from the log stream in Azure Portal.
Few errors and resolutions of this kind of error are:
If you have any startup.cs class, check if any error available where the errors were logged in Application Insights.
One of the reason is a missing app setting. Ensure you publish local settings as well.
If it didn't help then one of the reason could be platform issue and to confirm this we need to look into the backend logs on what was happing during that time resulting in 503 errors.
You can create the support ticket with Microsoft to assist you further.
According to this thread, one possible cause of 503 service-unavailable responses is when the service consumes more memory than what is available under the consumption (serverless) plan, causing the service to be evicted. Switching to a dedicated hosting plan can fix this issue. According to Microsoft's documentation, it appears that the function is allowed a maximum of 1,536MB of memory at one time. Of course, it could also be the case that your function is exceeding any of the other service limits associated with that plan, so my advice would be to add instrumentation and code defensively.
Got 503 after redeploying an Azure function.
Turned out the Python version had defaulted to 3.6, updated to 3.9 and started working.
I was using terraform and github actions
Related
I have a python function app created using ARM template. When i tried to deploy a function using the azure devops pipeline, I am facing the below error,
"Failed to deploy web package to App service. Service Temporary unavailable Code 503”
Usually the 503 error may be due to the server being overloaded or down for maintenance.
As Shariful said, the first thing you should check is that if your Function started or not.
If your Function prepared already and you didn't try too many times for deployment (if you do, try deploy later), you could consider another case that your server protection policy is improper.
For example, if your server's access policy was tweaked to a single
IP, limited to 10 requests per minute, and you usually click more than
100 connections per minute, the 503 Service Temporary unavailable
came up.
Then you should changed the single IP access limit from 10 to more than 100, the 503 error would disappear.
Here is an article about finding the reasons of 503 Service Temporarily Unavailable, you can have a look.
Solved by deleting and recreating the Azure Function. Nothing else seemed to work.
Within the Web App Down page in Diagnose and Solve for my Azure App Service I am seeing a series of 502 errors that have been occurring consistently for the past few hours. My site is unreachable upon browsing. I have tried restarting the app, and this has not helped. There have been no recent code deployments or configuration changes that led to this error.
Looking at the Microsoft Documentation I see:
https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-troubleshooting-502#cause-1
This seems to be an issue with the connectivity to the back end address pool that is behind a gateway which should be managed by Azure.
As you said, 502s generally indicate being unable to connect to back-end instances.
A solution to this can be to scale up or scale down your app service plan ensuring that you remain within the same tier (i.e. standard vs premium), so as to not change your inbound virtual IP, wait ~5 minutes, and then scale back.
Examples: S1 -> S2 or P2v2 -> P1v2
This operation, also referred to as the "scaling trick", allocates both new instances to the app service plan hosting your web apps, as well as a new internal load balancer.
In the event that there is a process hang-up caused by another resource running on the same hardware hosting your instance(s) and your site, this is the most efficient way to move your site to a new instance. Essentially, this functions as a hard reset beyond the capabilities of the traditional restart.
Lastly, because Azure bills by the hour and this temporary scale is for only 5 minutes, in the event that you need to scale up to remain in the same app service plan tier
(i.e. standard vs premium), you will face either negligible cost or no cost at all.
For future reference, in order to prevent this issue from re-occurring, if you have multiple instances running for your app then please consider enabling health check feature: https://learn.microsoft.com/en-us/azure/azure-monitor/platform/autoscale-get-started#route-traffic-to-healthy-instances-app-service
You can find other best practices here: https://azure.github.io/AppService/2020/05/15/Robust-Apps-for-the-cloud.html
I know this has been asked before, but I tried all known solutions and still no luck. I have a request that returns roughly 26MB of JSON. It is returning a 502 on my azure web app. I have set maxRequestLength and maxAllowedContentLength to their max allowed values as detailed here.
How to set the maxAllowedContentLength to 500MB while running on IIS7?
I have also set the applicationHost.xdt on the site folder of my webapp and verified it is applied as detailed here.
ApplicationHost.xdt in Azure Web Apps
None the less, my request timeout at exactly 4 minutes every time. I can run the same request against my localhost running on iisexpress pointed to the Azure SQL database and it returns the data, so I know this is something azure webapp speciic.
I have enabled all types of logging in "App Service Logs" section of my webapp. I see other failed request traces for 401 when session expires, but this request doesn't log a failed request trace, or an application error. In live log stream it shows the request as a 200 response in the web server logs.
Any other ideas?
Thanks for a detailed question and sharing the solutions that you have already tried. I'm unsure if "Always ON" feature is turned on on your WebApp. Such time-out error may occur due this,so kindly enable it and let us know for further investigation.
Additional information, Azure Load Balancer has a default idle timeout setting of approximately four minutes (230 sec); this is a general idle request timeout that will cause clients to get disconnected after 230 seconds. However, the command will still continue running server-side after that. For a typical scenario, this is generally a reasonable response time limit for a web request. In such scenarios, you could look at async methods to run additional reports. WebJobs or Azure Functions is another option.
If ‘Always On’ config is not turned On, please do turn it on. The AlwaysOn would help keep the app loaded even when there's no traffic, it will send a request to the ROOT of your application. Whatever file is delivered when a request is made to / is the one which will be warmed up and this feature comes with the App Service Plan is not charged separately
1) From the Azure Portal, go to your WebApp.
2) Select Settings> Configuration > General settings.
3) For Always On, select On.
I'm experiencing intermittent 503 Service Unavailable from azure storage.
Webjobs runner hosted as a top shelf service. Due to the fact that I used JobHost.Start() instead of JobHost.RunAndBlock() every time I get 503 from azure storage, service ends up in a corrupted stopping state.
When I switched to JobHost.RunAndBlock() using instead service is running continuously now but after 503 exception queue trigger stops polling queues.
I use standard azure queue trigger bindings. No manual setup.
Anyone experienced similar behaviour? How to recover from such connectivity errors?
Assuming you are using C# for your web job, I think using something like Polly or Enterprise Library's Transient Fault Handling Application Block to implement retry logic for when an occasional error occurs while using an Azure service, as you might be hitting a throttling thresholds (resource limit per your selected service tier).
Hope it helps!
I have an Azure service that has been running for a long period of time. It builds a word or powerpoint document based on arguments in the request and returns a uri to the build document. This is access via a visualforce page, when you click a button, it calls the service and displays a link to the document that has just been built. Simple.
All of a sudden, I get an apparently random 503 Service Unavailable error. Sometimes I click the button, no problem. Other times a 503 error. Each time the button triggers exactly the same request. Does anyone know why this might be happening?
Apparently doing the same thing over and over again and expecting a different result, is not insanity!
Thanks for taking the time to read this.
Looking at the monitoring on my service told me the processor was never exceeding 6% of usage, so it couldn't be a lack of resource causing these intermittent 503 errors. It's bizarre and I'm afraid I have no explanation for it, but simply redeploying the cloud service to Azure appears to have done the trick. It now works perfectly. The solution has not changed, so I can only imagine that whatever 'reboot' is necessary after deployment, has rectified whatever the problem was. All I can suggest is that you try the same thing if you are getting intermittent 503 errors.
For me the error went away when I set up auto-scaling. I think failover requests were getting routed to my second VM, and the second VM took some time to spin up because it wasn't ready for the activity. Auto-scaling shut down my second VM and the error no longer appears (I'm assuming it will spin up if/when I get enough traffic to use it).
Hope this also helps someone.
I get this error whenever I create an Azure Function with a storage account in the South Central US. If I use a storage account in a different region the function works.
Try a storage account in a different region than the one you are currently using to see if it resolves your issue.
503 error is simply shows that your application pool was inaccessible, it was intermittent because your application pool is restarting because the lack of resource (processor, memory, etc).
Scale up your instance (Cloud Services or VM) to get more resource for the application pool.