Azure function calling API yeild SocketException No such host is known

Question

Azure function calling API yeild SocketException No such host is known

Imran Qadir Baksh 1

We have Azure function that calling api.lokalise.com domain. But we are seeing too much errors for,

SocketException No such host is known

Does Azure function don't have internet to call HTTP API or does it depend upon Azure plan? We have plan (Y1: 0).

2 answers

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Answer 1

MayankBargali-MSFT 70,936 Moderator

@Imran Qadir Baksh Thanks for reaching out. As per the error it looks like a port exhaustion issue at your function app and I will suggest reviewing your function app code to reuse the connection to external services (api.lokalise.com) rather than creating a new connection for every request. I will also suggest you to review the function best practices and how to manage connection in function app to fix the issue.

You can always refer to Diagnostics and solve problems blade to get more insights on the issue along with the action plan to resolve the issue.

Feel free to get back to me if you need any assistance.

Imran Qadir Baksh 1 Reputation point

2022-06-13T06:27:37.36+00:00

Hi @MayankBargali-MSFT I am sure this is not port exhaustion as the function only send 3 requests per function execution.
MayankBargali-MSFT 70,936 Reputation points Moderator

2022-06-13T06:38:14.907+00:00

@Imran Qadir Baksh Thanks for your response. Can you confirm how many requests were sent to your function app (your function was executed) during that time? If you are not creating the static client, then for every function invocation there be a total of n * 3 sockets that will be created for communicating with your outside service. Have you reviewed the Diagnostics and solve problems blade on your function app to get more insights on the issue?
satish 1 Reputation point

2022-06-16T11:57:07.673+00:00

@MayankBargali-MSFT . I am also facing the same issue. Please see bellow error message. it running fine in local system but same code base throwing error when i run from azure portal.

No such host is known. (xxxx:443) @ System.Net.Sockets.SocketException (xxx): No such host is known.at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|277_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
Thank you for your support
Imran Qadir Baksh 1 Reputation point

2022-06-16T13:52:06.553+00:00

The client is static and requests are 3 as I said. As I said before it happens only sometimes. Look like Azure is doing something with Network.
MayankBargali-MSFT 70,936 Reputation points Moderator

2022-06-16T14:22:24.393+00:00

@Imran Qadir Baksh Thanks for your response. This needs to troubleshoot it further from the backend logs. Can you please refer to my private comment so you can share more details so I can review the logs.
MayankBargali-MSFT 70,936 Reputation points Moderator

2022-06-16T14:23:44.807+00:00

@satish Thanks for reaching out. Can you share more details on to my private comment so I can review the backend logs and assist you further.

Answer 2

@MayankBargali-MSFT I am also facing the same issue. I am trying to reach an API from an Azure Function on a Consumption plan, and it randomly comes back with thie "No such host is known" exception. I hade 20 request during this weekend that hade failed.

I started an instance of my function on my local machine and hade the function running in azure also. The azure function is triggered by a message in a Storage queue, and when I put the 20 failed messages in the queue. 16 was picked up by my local machine and executed correctly, and 4 was picked up the function in azure and all failed with this "No such host is known" exception.

I am using a static HttpClient and is doing 1 request, so I don't think there is an issue with to many connections.

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Azure function calling API yeild SocketException No such host is known

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