AWS Lambda - Unable to connect to SQL Server RDS

Question

Hi I was having the same problem as this post but the posted answer (no sample code) wasn't provided so I will start a new thread and ask you guys.

I have created a AWS Serverless Application (.Net Core) project for our lambda function and below code is what I used to connect in AWS RDS.

---

string ConnectionString = "Data Source=rds4abc1190.asdfqwerqb9l.us-east-1.rds.amazonaws.com,2855;Initial Catalog=MyDatabase;Persist Security Info=True;User ID=myID;Password=mypassword;Encrypt=False";

using (var Conn = new SqlConnection(ConnectionString))
{
     using (var Cmd = new SqlCommand("SELECT * from Customer", Conn))
     {
          Conn.Open(); //<-- this is where the error fires.

          SqlDataReader rdr = Cmd.ExecuteReader();
          while (rdr.Read())
          {
                myDbItems.Add(rdr[1].ToString());
          }

          Conn.Close();
      }
 }

---

Using the above code works fine when running on local machine but if deployed in AWS Api Gateway, that code would error.

"errorType": "SqlException", "errorMessage": "Connection Timeout Expired. The timeout period elapsed during the post-login phase. The connection could have timed out while waiting for server to complete the login process and respond; Or it could have timed out while attempting to create multiple active connections. The duration spent while attempting to connect to this server was - [Pre-Login] initialization=781; handshake=1957; [Login] initialization=40; authentication=122; [Post-Login] complete=12219;",

Answer 1

Added the following in each function in the serverless.template.

"Role": "arn:aws:iam::053984854873:role/1234-Dev",              
    "Policies": [ "AWSLambdaBasicExecutionRole", "AWSLambdaBasicExecutionRole-ABC1234","LambdaAccess-1234" ], 
    "VpcConfig" : {
        "SecurityGroupIds" : ["sg-4f2cbff1","sg-3584a444"],
        "SubnetIds" : ["subnet-f2520727","subnet-388b4ab2"]
    }

Answer 2

If the answer is the same as the referenced post, then there wasn't any sample code because it isn't a code issue. He upgraded the database engine version in RDS because the drivers that AWS Lambda uses wouldn't support connections to MSSQL 2008 R2, while his local machine had the necessary drivers.

Here is the AWS doc on upgrading RDS SQL Server Engine versions:

http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.SQLServer.html