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The app is giving 503 error when deployed to staging slot.

Aishwarya Rao 0 Reputation points Microsoft Employee
2024-07-04T17:39:31.2966667+00:00

The app is giving 503 error when deployed to staging slot. Changes made include storage account access changes via managed identity. With the managed identity flag turned on, the app service does not come up in staging slot due to which swap operation fails and deployment fails

Azure App Service
Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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  1. Ganeshkumar R 590 Reputation points
    2024-07-04T18:09:57.0166667+00:00

    Hello,
    A 503 Service Unavailable error typically indicates that the server is unable to handle the request due to temporary overloading or maintenance of the server. In the context of Azure App Services, there are several potential causes, especially considering your recent changes related to managed identity and storage account access. Here are steps to troubleshoot and resolve the issue:

    Steps to Troubleshoot and Resolve 503 Error

    1. Check App Service Configuration

    • Managed Identity Configuration:
      • Ensure that the managed identity is enabled for the staging slot.
      • Verify that the managed identity has the necessary permissions to access the storage account.
      • Go to the Azure portal, select your App Service, and then navigate to the Identity section to confirm the managed identity settings.
    • Connection Strings and App Settings:
      • Ensure that the connection strings and app settings are correctly configured in the staging slot.
      • Verify that any references to the storage account in your configuration are using the managed identity.

    2. Verify Storage Account Access

    • Role Assignments:
      • Ensure that the managed identity has been assigned the appropriate role (e.g., Storage Blob Data Contributor) for the storage account.
      • Go to the Azure portal, navigate to the storage account, and check the Access control (IAM) section to verify role assignments.
    • Access Policies:
      • If you are using a storage account with firewall rules or virtual network restrictions, ensure that the App Service is allowed to access the storage account.

    3. Logs and Diagnostics

    • Application Logs:
      • Enable application logging in the Azure portal to capture detailed logs.
      • Check the application logs for any specific error messages that could indicate the root cause.
    • App Service Diagnostics:
      • Use the Diagnose and solve problems tool in the Azure portal. This tool can help identify common issues with your App Service.
      • Navigate to your App Service, select Diagnose and solve problems, and follow the guided steps.

    4. Network and Firewall Settings

    • VNet Integration:
      • If your App Service is integrated with a Virtual Network (VNet), ensure that the network configuration allows access to the storage account.
      • Verify that the VNet rules are correctly configured in the storage account.
    • NSG (Network Security Group) Rules:
      • Check any NSG rules that might be blocking access to the storage account from the App Service.

    5. Testing Managed Identity Permissions

    • Test via Azure CLI or PowerShell:
      • Use Azure CLI or PowerShell to test the managed identity's access to the storage account.
      • Example using Azure CLI: 
        
    # Get the access token for the managed identity

    az account get-access-token --resource https://storage.azure.com/

    # Test access to the storage account

    az storage blob list --account-name <YourStorageAccountName> --container-name <YourContainerName> --auth-mode login

    6. Review Deployment Logs

    • Deployment Center:
      • Check the deployment logs in the Deployment Center to identify any issues that occurred during the deployment process.
      • Navigate to your App Service, select Deployment Center, and review the logs.

    Example: Assigning Roles to Managed Identity

    1. Enable Managed Identity:
      • Go to your App Service in the Azure portal.
      • Navigate to Identity and enable the System assigned managed identity.
    2. Assign Role to Managed Identity:
      • Go to your Storage Account.
      • Navigate to Access control (IAM) > Add role assignment.
      • Select the role (e.g., Storage Blob Data Contributor).
      • Assign the role to the managed identity of your App Service.

    Example: Enabling Application Logs

    1. Navigate to App Service:
      • In the Azure portal, go to your App Service.
    2. Enable Application Logging:
      • Go to Diagnostics logs.
      • Turn on Application Logging (Filesystem) and configure the log level.
      • Save the settings and monitor the logs for any errors.

    By following these steps, you should be able to identify and resolve the issue causing the 503 error when deploying to the staging slot. If the issue persists, consider reaching out to Azure support for further assistance.

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