[SOLVED] Enabling a container to communicate with SQL Server in a separate container

Enabling a container to communicate with SQL Server in a separate container

I have two containers I'm managing with TestContainers in a .NET environment. One container is using MsSqlBuilder like so:

var sqlContainer = new MsSqlBuilder()
            .WithImage("mcr.microsoft.com/mssql/server:2022-latest")
            .WithPassword("Passw0rd#123")
            .WithNetwork(network)
            .WithWaitStrategy(Wait.ForUnixContainer().UntilCommandIsCompleted("/opt/mssql-tools18/bin/sqlcmd -C -S localhost -U sa -P \"Passw0rd#123\" -Q \"SELECT 1\" -b -o /dev/null"))
            .Build();

I have another container running an Azure Function app like so:

var functionContainer = new ContainerBuilder()
            .WithImage(image)
            .WithPortBinding(80, true)
            .WithWaitStrategy(Wait.ForUnixContainer().UntilHttpRequestIsSucceeded(r => r.ForPort(80), strategy => strategy.WithTimeout(30.Seconds())))
            .WithNetwork(network)
            .WithEnvironment(new Dictionary<string, string>
            {
                { "ConnectionStrings:Notification", notificationConnectionString }
            });

I'm able to launch the Azure Function app, but when I attempt to call an endpoint that communicates with my SQL Server container, I get the following message:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections.

I am able to communicate with the SQL Server image from my host machine, so I'm sure I'm just missing a network setting. Here's how I am initializing my network:

var network = new NetworkBuilder()
            .WithName(Guid.NewGuid().ToString("D"))
            .Build();

I need to make my Azure Functions container communicate with my SQL Server container, and I thought putting them on the same network would do it. I am able to verify that the connection string is being set properly because I'm able to connect using that same connection string on my host machine.

Solution

My issue was caused by not including .WithHostname(hostName) on my SQL Container Builder, and by using a connection string that used 127.0.0.1 instead of that hostName.