We use the following testing program to start a port forwarding session by AWS SDK in C#, and the program finishes running without any issue. However, after the program finishes running, the session terminates in less than 30 seconds.

More information:

It looks like, the sessions started by the SDK do not really work. We are still looking for why.

We developed unit tests to start a session and immediately followed by a login request to connect to the database. And the result is:

• If the session was started by C# calling commands of AWS CLI, the test passes.

• If the session was started by C# calling APIs in SDK, the test fails with the following error message:

  MySQL login failed.
  ex.Message: Unable to connect to any of the specified MySQL hosts.

If we use AWS CLI instead of SDK, the following command can start a session and persist. The command will keep running and the session keeps working and accepting requests. Until we press Control + C, the process gets killed and the session terminates.

Therefore, we believe our credentials do not have any issue.

aws ssm start-session \
  --target "i-xxx" --region "xxxxxxx" --profile "profile_name" \
  --document-name "AWS-StartPortForwardingSessionToRemoteHost" \
  --parameters host="xxxx-database-cluster.xxx.rds.amazonaws",portNumber="3306",localPortNumber="3306"

We prefer to use SDK because it provides better functionality for programmatical usage, so please point out if we missed anything in the program.

Details

Note: The following testing source code automatically refers to the default location in ~/.aws/ for its config and credentials files.

public static async Task CallSDKAsync()
{
    // Load AWS credentials from the specified profile
    var credentials = new Amazon.Runtime.StoredProfileAWSCredentials(SensitiveData.AwsProfile);

    // Create the SSM client using the credentials
    var client = new AmazonSimpleSystemsManagementClient(credentials, SensitiveData.AwsRegionEndpoint);

    // Define the port forwarding parameters
    var startSessionRequest = new StartSessionRequest
    {
        DocumentName = "AWS-StartPortForwardingSessionToRemoteHost",
        Parameters = new Dictionary<string, List<string>>()
        {
            { "host", new List<string> { SensitiveData.DatabaseHost } },
            { "portNumber", new List<string> { "3306" } },
            { "localPortNumber", new List<string> { "3306" } }
        },
        Target = SensitiveData.AwsInstanceId
    };

    try
    {
        var response = await client.StartSessionAsync(startSessionRequest);
        Console.WriteLine(response.ToString());
        Console.WriteLine("Session started successfully.");

    }
    catch (AmazonServiceException amazonEx)
    {
        Console.WriteLine($"AWS Service error: {amazonEx.Message}");
        Console.WriteLine($"Status Code: {amazonEx.StatusCode}");
        Console.WriteLine($"AWS Error Code: {amazonEx.ErrorCode}");
        Console.WriteLine($"Request ID: {amazonEx.RequestId}");
        Console.WriteLine($"AWS Error Type: {amazonEx.ErrorType}");
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error: {ex.Message}");
        Console.WriteLine(ex.InnerException?.Message);
    }
}