Docker-compose SQL Server Create then attach_dbs (windows) - sql-server

Question

The end game is to create a database when building a docker container, and persist the data so that if the container is removed, I can start the container again and have my database with my persisted data.
I'm using microsoft/mssql-server-windows-developer with Windows containers with docker-compose.
The relevant part of my docker-compose file is (other services removed):
version: "3.9" services:
db:
build:
context: .
dockerfile: Database/Dockerfile
volumes:
- C:\temp:C:\temp
ports:
- 1433:1433
Basically, the db Dockerfile runs a powershell script (very similar to https://github.com/microsoft/mssql-docker/blob/master/windows/mssql-server-windows-developer/start.ps1). My powershell script starts MSSQLSERVER then runs sql files to create a database, run create table, create procs, etc scripts.
All of this works. docker-compose build then docker-compose up will create and run my database on localhost and everything is great. But, if I manipulate the data at all and remove the database then call docker-compose up again, my data is gone.
Everything I've read about persisting data includes using attach_db. I would like to do some sort of if exists, attach_db else create database.
The question (finally)... Why don't I have an mdf file after I create the database? Am I supposed to? I've messed with different ways to add volumes but my volume is always empty. It doesn't appear I'm creating an mdf file to add to my volume.
EDIT - Adding Dockerfile and ps script Dockerfile calls
Dockerfile:
FROM microsoft/mssql-server-windows-developer
ENV sa_password="nannynannybooboo" \
ACCEPT_EULA="Y" \
db1="db1" \
db2="db2"
EXPOSE 1433
RUN mkdir -p ./db1
RUN mkdir -p ./db2
COPY /Database/startsql.ps1 .
COPY /Database/db1/ ./db1
COPY /Database/db2/ ./db2
HEALTHCHECK CMD [ "sqlcmd", "-Q", "select 2" ]
RUN .\startsql -sa_password $env:sa_password -ACCEPT_EULA $env:ACCEPT_EULA -db_name $env:db2 -Verbose
RUN .\startsql -sa_password $env:sa_password -ACCEPT_EULA $env:ACCEPT_EULA -db_name $env:db1 -Verbose
startsql.ps1
# based off https://github.com/microsoft/mssql-docker/blob/master/windows/mssql-server-windows-developer/start.ps1
param(
[Parameter(Mandatory=$false)]
[string]$sa_password,
[Parameter(Mandatory=$false)]
[string]$ACCEPT_EULA,
[Parameter(Mandatory=$true)]
[string]$db_name
)
if($ACCEPT_EULA -ne "Y" -And $ACCEPT_EULA -ne "y")
{
Write-Verbose "ERROR: You must accept the End User License Agreement before this container can start."
Write-Verbose "Set the environment variable ACCEPT_EULA to 'Y' if you accept the agreement."
exit 1
}
# start the service
Write-Verbose "Starting SQL Server"
start-service MSSQLSERVER
if($sa_password -eq "_") {
if (Test-Path $env:sa_password_path) {
$sa_password = Get-Content -Raw $secretPath
}
else {
Write-Verbose "WARN: Using default SA password, secret file not found at: $secretPath"
}
}
Write-Verbose $sa_password
if($sa_password -ne "_")
{
Write-Verbose "Changing SA login credentials"
$sqlcmd = "ALTER LOGIN sa with password=" +"'" + $sa_password + "'" + ";ALTER LOGIN sa ENABLE;"
& sqlcmd -Q $sqlcmd
}
Write-Verbose "Started SQL Server"
Write-Verbose "Starting set up scripts..."
Write-Verbose $db_name
$exists = $true
$exists = #($sqlServer.Databases | % { $_.Name }) -contains $db_name
$creation = ".\"+$db_name+"\creation.sql"
$creation_rpt = ".\"+$db_name+"\creation.rpt"
$userdefined = ".\"+$db_name+"\userdefined.sql"
$userdefined_rpt = ".\"+$db_name+"\userdefined.rpt"
$presetup = ".\"+$db_name+"\pre.setup.sql"
$presetup_rpt = ".\"+$db_name+"\presetup.rpt"
$tables = ".\"+$db_name+"\tables.sql"
$tables_rpt = ".\"+$db_name+"\tables.rpt"
$procs = ".\"+$db_name+"\procs.sql"
$procs_rpt = ".\"+$db_name+"\procs.rpt"
$triggers = ".\"+$db_name+"\triggers.sql"
$triggers_rpt = ".\"+$db_name+"\triggers.rpt"
Write-Verbose $creation
Write-Verbose $exists
if ($exists -ne $true){
Write-Verbose "Starting creation script..."
Invoke-Sqlcmd -InputFile $creation | Out-File -FilePath $creation_rpt
Write-Verbose "Starting user defined script..."
Invoke-Sqlcmd -InputFile $userdefined | Out-File -FilePath $userdefined_rpt
Write-Verbose "Starting pre.setup script..."
Invoke-Sqlcmd -InputFile $presetup | Out-File -FilePath $presetup_rpt
Write-Verbose "Starting tables script..."
Invoke-Sqlcmd -InputFile $tables | Out-File -FilePath $tables_rpt
Write-Verbose "Starting triggers script..."
Invoke-Sqlcmd -InputFile $triggers | Out-File -FilePath $triggers_rpt
Write-Verbose "Starting procs script..."
Invoke-Sqlcmd -InputFile $procs | Out-File -FilePath $procs_rpt
}
Get-EventLog -LogName Application -Source "MSSQL*" -After (Get-Date).AddSeconds(-2) | Select-Object TimeGenerated, EntryType, Message
I can't share the sql files startsql calls, but 99% of the sql
is SSMS generate scripts from an existing DB that I am replicating. The 1% that isn't generated by SSMS is a command to link the two databases being created.

Answer 1

Volumes
You're spot on, volumes can (And should!) be used to persist your data.
Microsoft themselves have docs on how to persist data from containerised SQL servers, including the required commands:
https://learn.microsoft.com/en-us/sql/linux/sql-server-linux-docker-container-configure?view=sql-server-ver15&pivots=cs1-bash#persist
However, this is for Linux, not Windows, so the paths will be different (Very likely the defaults for non-containerised work)
To find that location, you could probably use a query found below, or hop into the container while it is running (using docker exec) and navigate around:
https://www.netwrix.com/how_to_view_sql_server_database_file_location.html
When using volumes with docker-compose the spec can be found here, and is really simple to follow:
https://docs.docker.com/storage/volumes/#use-a-volume-with-docker-compose
(Edit) Proof of Concept
I played around with the Windows container and managed to get the volumes working fine.
I ditched your Dockerfile, and just used the base container image, see below.
version: "3.9"
services:
db:
image: microsoft/mssql-server-windows-developer
volumes:
- .\db:C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA
ports:
- 1433:1433
environment:
SA_PASSWORD: "Abc12345678"
ACCEPT_EULA: "Y"
This works for me because I specified the MDF file location upon database creation:
/*
https://learn.microsoft.com/en-us/sql/relational-databases/databases/create-a-database?view=sql-server-ver15
*/
USE master ;
GO
CREATE DATABASE Sales
ON
( NAME = Sales_dat,
FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA\saledat.mdf',
SIZE = 10,
MAXSIZE = 50,
FILEGROWTH = 5 )
LOG ON
( NAME = Sales_log,
FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA\salelog.ldf',
SIZE = 5MB,
MAXSIZE = 25MB,
FILEGROWTH = 5MB ) ;
GO
EXEC sp_databases ;
You can see that the filepath in the container there correlates to the volume path in the docker-compose file. When I stopped the container, I could successfully see the mdf file in the .\db folder of my project. If you managed to locate the filepath from running your query, you can simply add that to the volume spec in the same fashion as above.When restarting the container, everything loaded fine, and the SP returned a valid list of all DB's.
Windows Containers
I knew they were regarded as a bad idea, but me oh my, did I not expect the base image to be 15GB.
This is ridiculously large, and depending on your use case, will present issues with the development, and deployment process, simply in terms of the time required to download the image.
If you can use Linux containers for your purposes, I highly recommend it as they are production ready, small, lightweight, and better supported. They can even be ran as the developer edition, and the Microsoft docs clearly state how to persist data from these containers
Linux: https://hub.docker.com/_/microsoft-mssql-server
Windows: https://hub.docker.com/r/microsoft/mssql-server-windows-developer/
Ex:
# Using Windows containers in Powershell
PS> docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
microsoft/mssql-server-windows-developer latest 19873f41b375 3 years ago 15.1GB
# Using Linux containers in WSL
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
mcr.microsoft.com/mssql/server 2019-latest 56beb1db7406 10 days ago 1.54GB