I have an ASP.Net core web API that connects to a MySQL server running in AWS (RDS).
This database is public (with public IP) and I can access it from MySQL workbench.
The app work perfectly when I execute it in HTTP mode and It is able to connect to the database without any problem.
However, when I start it in docker, the app run fine but it is unable to connect to the database.
I am using dapper and connect to database with this code:
 db = new MySqlConnection(masterConnection);
 await db.OpenAsync();
Error:
MySqlConnector.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts.
   at MySqlConnector.Core.ServerSession.OpenTcpSocketAsync(ConnectionSettings cs, ILoadBalancer loadBalancer, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ServerSession.cs:line 1146
   at MySqlConnector.Core.ServerSession.ConnectAsync(ConnectionSettings cs, MySqlConnection connection, Int32 startTickCount, ILoadBalancer loadBalancer, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ServerSession.cs:line 438
   at MySqlConnector.Core.ConnectionPool.ConnectSessionAsync(MySqlConnection connection, String logMessage, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 403
   at MySqlConnector.Core.ConnectionPool.ConnectSessionAsync(MySqlConnection connection, String logMessage, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 408
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 98
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 128
   at MySqlConnector.MySqlConnection.CreateSessionAsync(ConnectionPool pool, Int32 startTickCount, Activity activity, Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 929
   at MySqlConnector.MySqlConnection.OpenAsync(Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 423
   at coolco_backend.Data.CollectiblesData.GetCollectiblesByUserId(Int32 idUser) in E:\Apes\Proyectos\coolco-backend\Data\CollectiblesData.cs:line 28
   at coolco_backend.Domain.CollectiblesDomain.GetCollectiblesByUserId(Int32 id) in E:\Apes\Proyectos\coolco-backend\Domain\CollectiblesDomain.cs:line 28
   at coolco_backend.Controllers.CollectiblesController.GetContentByIdUser(Int32 idUser) in E:\Apes\Proyectos\coolco-backend\Controllers\CollectiblesController.cs:line 23
   at lambda_method8(Closure, Object)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(ActionContext actionContext, IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
 
    