Enable env var for auto creation of MSSQL_DB if var exists and db does not

[potatoqualitee]

This will help enable database creation at startup.

You can either add it into your compose file

    container_name: mssql1
    hostname: mssql1
    image: dbatools/sqlinstance1
    environment:
      - MSSQL_DB=mydb1
    .......
    container_name: mssql2
    hostname: mssql2
    image: dbatools/sqlinstance2
    environment:
      - MSSQL_DB=mydb2

or at the command line

docker run -p 1433:1433  --volume shared:/shared:z --name mssql1 --hostname mssql1 --network localnet --env MSSQL_DB=mydb1 -d dbatools/sqlinstance
docker run -p 14333:1433  --volume shared:/shared:z --name mssql2 --hostname mssql2 --network localnet --env MSSQL_DB=mydb2 -d dbatools/sqlinstance2

To fill need for microsoft/mssql-docker#2 and microsoft/mssql-docker#11. Hat tip 🤠 to https://github.com/twright-msft/mssql-node-docker-demo-app/blob/master/entrypoint.sh

So far this has not been tested on ARM/Edge. Thanks for the 607,356 image pulls as of today! Who knew the empty sqlinstance2 would be twice as popular?

[potatoqualitee]

Look into using init.d, entrypoint.d or docker-entrypoint-initdb.d as suggested by the users.