Azure App Service - 502 Bad Gateway When Using VNet Integration with On-Premises API
I just started working with I'm trying to implement I'm working with a frustrating scenario with my Azure App Service when trying to access an on-premises API through VNet integration... After setting up the VNet integration and configuring the necessary subnets and network security groups, I deployed my .NET Core web application, but all requests to the on-premises API result in a 502 Bad Gateway behavior. The API is accessible from within the VNet, as I can reach it from an Azure Virtual Machine in the same subnet. Here's a snippet of the code I am using to call the API: ```csharp using System.Net.Http; using System.Threading.Tasks; public class ApiService { private readonly HttpClient _httpClient; public ApiService(HttpClient httpClient) { _httpClient = httpClient; } public async Task<string> GetDataAsync() { var response = await _httpClient.GetAsync("http://my-onprem-api.local/data"); response.EnsureSuccessStatusCode(); return await response.Content.ReadAsStringAsync(); } } ``` I've verified that the App Service is correctly configured to use the VNet with the following settings: - **VNet Integration**: Enabled on the App Service - **Subnet**: Configured with sufficient IP addresses and no other services - **Network Security Groups**: Allowing traffic from the App Service to the API I also checked the App Service's outbound IP addresses and ensured that they are whitelisted in the on-premises firewall. Despite all this, I'm still getting the 502 Bad Gateway behavior, which seems to indicate that the App Service want to communicate with the API. I logged into the Azure portal and checked the App Service logs, but there are no additional behavior messages that could provide clues. I've also tried accessing the API from the Azure Cloud Shell using the same HTTP client but received a similar 502 behavior. I'm running out of ideas here. Any guidance on how to troubleshoot or fix this scenario would be greatly appreciated! My development environment is Linux. What's the best practice here? I'm working in a macOS environment. Thanks for any help you can provide! My development environment is CentOS.