Azure App Service - Azure Database for MySQL flexible server - VNet integration / private connection (DNS)

Question

Azure App Service - Azure Database for MySQL flexible server - VNet integration / private connection (DNS)

PeterT94 0

Hello everyone,

Recently I created a new Azure Database for MySQL flexible server and connected an already existing Azure App Service to the newly created DB MySQL flexible server via VNet integration with a private DNS zone.

The connection seems to work fine, however, at random moments the Database is unreachable for the App Service for about 5-15 minutes. When then going to the App Service website, it shows the following error:

Open database error php_network_getaddresses: getaddrinfo failed: No such host is known. Application error

I have tried many things, adding a Connection String, adding a Service Connector, etc.
I just cannot find the issue.

Is it perhaps because I configured the private connection incorrectly?
Have I added the connection string or service connector the wrong way?

Does anyone perhaps know what else I could try?
Or could someone tell me the exact steps to configure the private connection between the App Service and Database server?

Thank you in advance.

Answer 1

brtrach-MSFT 11,936 Microsoft Employee

@PeterT94 Can you start with the below 5 steps? Let me know if none of them resolve the issue by replying to this message and we can assist you further.

Check the logs: Check the logs for your Azure App Service and Azure Database for MySQL flexible server to see if there are any error messages or warnings that could indicate the cause of the issue.

Check the VNet integration: Verify that the VNet integration between your Azure App Service and Azure Database for MySQL flexible server is configured correctly. Ensure that the VNet and subnet are correctly configured, and that the private DNS zone is correctly set up.

Check the firewall rules: Verify that the firewall rules for your Azure Database for MySQL flexible server are correctly configured to allow traffic from the VNet.

Check the connection string: Verify that the connection string for your Azure App Service is correctly configured to use the private DNS zone and VNet integration.

Check the service endpoint: Verify that the service endpoint for your Azure Database for MySQL flexible server is correctly configured to allow traffic from the VNet.

PeterT94 0 Reputation points

2023-11-13T12:54:56.75+00:00

Thank you for your message

Edit: see below new comment
PeterT94 0 Reputation points

2023-11-13T17:22:59.4266667+00:00
@brtrach-MSFT to add: I have just configured everything from scratch. Below are the steps that I executed. Also an image below of the situation how I'd like it to be:

In my existing VNet, I created 2 new subnets:

AppSvcSubnet (192.168.102.0/24)

PrivateLinkSubnet (192.168.103.0/24)

In my existing Azure Database for MySQL Flexible Server, I created a private endpoint and linked this to the Azure Database for MySQL Flexible Server. I assigned it to the subnet PrivateLinkSubnet (192.168.103.0./24) that I created above.
In the DNS option, I selected "Integrate with Private DNS zone: Yes". I placed this in the same resource group as the App Service and Azure Database for MySQL Flexible Server.

Finally, in the existing App Service, I configured the VNet integration to use the subnet AppSvcSubnet (192.168.102.0/24) that I created above.

These are the steps that I have done so far.
The Connection String in the App Service is currently not configured. Will I still have to configure this? If yes, what would the connection string have to be that I have to configure?

Am I still missing something else or are the above steps correct?

Thank you.
brtrach-MSFT 11,936 Reputation points Microsoft Employee

2023-11-14T03:18:05.2+00:00
Yes, everything there looks good on paper so far.

To connect to the Azure Database for MySQL flexible server, you need to provide the connection string in the App Service. You can add the connection string in the App Service by following these steps:

Go to the App Service in the Azure portal.

Click on the "Configuration" blade.

Click on the "New connection string" button.

Enter the following details:

Name: Enter a name for the connection string.

Value: Enter the connection string for the Azure Database for MySQL flexible server. The connection string should be in the following format:
Server=tcp:<server-name>.mysql.database.azure.com,3306;Database=<database-name>;User ID=<user-name>@<server-name>;Password=<password>;Encrypt=true;Connection Timeout=30; Replace <server-name>, <database-name>, <user-name>, and <password> with the appropriate values for your Azure Database for MySQL flexible server.

Type: Select "MySQL".

Click on the "OK" button to save the connection string.

Let me know if you encounter any trouble with the configuration. We would be happy to assist.
PeterT94 0 Reputation points

2023-11-14T09:14:30.6233333+00:00

Thank you @brtrach-MSFT !

Regarding the connection string, by the value "database-name", do you mean the name of the database that I added manually under the "Databases" blade at the Azure Database for MySQL flexible server page?

And for the user-name and password values, is it the username and password of the same database that I added manually like mentioned above or is it the username and password of the Azure Database for MySQL flexible server itself (which I created when creating the Azure Database for MySQL flexible server)?
PeterT94 0 Reputation points

2023-11-15T16:59:08.1833333+00:00

@brtrach-MSFT to add to the above question. I am unable to connect to my Azure Database for MySQL flexible server. I tried connecting through MySQL Workbench (followed all the steps in the connection blade), but when connecting it says "Failed to connect to .... " "Unable to connect to localhost".
brtrach-MSFT 11,936 Reputation points Microsoft Employee

2023-11-21T01:44:36.35+00:00

@PeterT94 My apologies for the delay, I was out for a few days.

Yes, by "database-name" we mean the name of the database that you added manually under the "Databases" blade at the Azure Database for MySQL flexible server page.

For the "user-name" and "password" values, you need to use the username and password of the database user that you created when you added the database manually. This is not the same as the username and password of the Azure Database for MySQL flexible server itself.

Regarding the connection issue you are facing, it seems that you are trying to connect to the MySQL server on your local machine (localhost) instead of the Azure Database for MySQL flexible server. Please make sure that you are using the correct hostname or IP address for the Azure Database for MySQL flexible server in your connection string. You can find the hostname or IP address in the "Overview" blade of your Azure Database for MySQL flexible server in the Azure portal.

If you are still unable to connect, please let us know and we can investigate further.

Azure App Service - Azure Database for MySQL flexible server - VNet integration / private connection (DNS)

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