The following describes how to run SQL Server Express instance in a Docker Container .The quick way to ‘install’ a SQL Express, is to run a Docker container from the mssql-server-linuximage. You can start one by running the following command from cmd or powershell.

docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=Pass@word" -e "MSSQL_PID=Express" -p 1433:1433 -d --name=mssqlexpress  mcr.microsoft.com/mssql/server:latest

The above command will start a background Docker container named ‘sqlsrvr’. The SA password is Pass@word

From any application , you may connect using this connection string

Server=localhost,1433;Initial Catalog=Testdb;Integrated Security=True;User Id=sa;Password=Pass@word

Also , the container exposes the container port 1433 to the localhost on 1433, which is used for communication if this conflicts with your setup / any other SQL instance you have running on your local machine , you may either stop the running SQL instance using services.msc or try to run the container on another host port.

For e.g the below code we are mapping the SQL server port 1433 to 1439 on the host machine

docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=MyPass@word" -e "MSSQL_PID=Express" -p 1439:1433 -d --name=mssqlexpress mcr.microsoft.com/mssql/server:latest

Connecting via SSMS should be fairly straightforward

connected

Starting and Stopping the sql container

docker start mssqlexpress
docker stop mssqlexpress

The running sql container is volatile i.e if you remove the container, the data is gone with it.

To persist your data, you need to mount it to a Docker volume / docker mount

A Docker volume maps a directory within a container file system to a path on the host file system . In the sample below, we’ll map the d:\LocalDB\SQLExpress\Datafiles on a Windows host to the datafolder from the mssql-server-linux container, on path/var/opt/mssql/data

for e.g below is the command and followed by it’s explanation

• docker run: This is the command to create and start a new Docker container.
• -e "ACCEPT_EULA=Y": This sets an environment variable ACCEPT_EULA to Y, which indicates that you accept the End User License Agreement.
• -e "SA_PASSWORD=pass@word1": This sets another environment variable SA_PASSWORD with the value pass@word1. This password will be used for the SQL Server sa (system administrator) account.
• -e "MSSQL_PID=Express": This sets the MSSQL_PID environment variable to Express, specifying that you want to use the SQL Server Express edition.
• -p 1433:1433: This maps port 1433 of your host machine to port 1433 of the Docker container. SQL Server listens on port 1433 by default.
• -d: This runs the container in detached mode, which means it will run in the background.
• --name=mssqlexpress: This assigns a name to the container, which in this case is mssqlexpress.
• --mount type=bind,source=d:\\LocalDB\\SQLExpress\\Datafiles,target=/var/opt/mssql/data: This binds a directory from your host machine (d:\\LocalDB\\SQLExpress\\Datafiles) to a directory inside the container (/var/opt/mssql/data). This allows the container to use the data files from your host machine.
• mcr.microsoft.com/mssql/server:latest: This specifies the Docker image to use, which in this case is the latest version of the SQL Server image from the Microsoft Container Registry.

You can now back up database files and use it to restore the back up files created at your mounted path d:\\LocalDB\\SQLExpress\\Datafiles