connection string for sqlserver in Docker container

sudo docker pull microsoft/mssql-server-linux:2017-latest
docker run \
  -e 'ACCEPT_EULA=Y' \
  -e 'MSSQL_SA_PASSWORD=YourSTRONG!Passw0rd' \
  -p 1401:1433 \
  -n sql1 \
  -d microsoft/mssql-server-linux:2017-latest

then,

private static string _connStr = @"
  Server=127.0.0.1,1401;
  Database=Master;
  User Id=SA;
  Password=YourSTRONG!Passw0rd";