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;",

Is you lambda resides inside a VPC subnet that is in the same VPC as the SQLServer having access to the SQLServer RDS subnet? — Ashan

Chraisler Zyre Chraisler Zyre · Accepted Answer · 2017-07-12T01:28:31

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"]
    }

AWS Lambda - Unable to connect to SQL Server RDS

2 Answers