docker-compose on Windows volume not working

Question

I've been playing with Docker for the past week and think the container idea is very useful, but despite reading everything I can for the past 3 days I can't get the volume mapping to work

get docker-compose to use my existing volume.

    Docker Version: 18.03.1-ce
    docker-compose version 1.21.1, build 7641a569

I created a volume using the following via a Dockerfile

    # Reference SQL image
    FROM microsoft/mssql-server-windows-developer

    # Create directory within SQL container for database files mapped to the    volume
    VOLUME sqldata:c:/MSSQL

and here it shows:
    C:\ProgramData\Docker\volumes>docker volume ls
    local               sqldata

Now I've tried probably 60+ different "solutions" based on StackOverflow and Docker forums, but none of them work. (Note despite the names below with Azure I am simply trying to get this to run locally, Azure is next hurdle)

    Docker-compose.yaml:

    version: '3.4'
    services:
      ws:
        image: wsManager
        container_name: azure-wcf
        ports:
           - "80"
        depends_on:
            - db

      db:
        image: dbimage:latest
        container_name: azure-db
        volumes:
             - \sqldata:/mssql
#            - type: volume
#              source: sqldata
#              target: /mssql
        ports:
            - "1433"

I've added a volumes section but it does not help, 

    volumes:
        sqldata:
            external:
                name: sqldata

    changed the - \sqldata:/mssql
    to every possible slash .. . ~ whatever.  Moved the file to yaml file 

to C:\ProgramData\Docker\volumes - basically any suggestion that showed in my search results. The dbImage is a SQL Server image that I need to persist the data from but am wondering what the magic is as nothing I've tried works. Any help is GREATLY appreciated.

I'm running on Windows 10 Pro build 1803.

Why does this have to be so hard? Than you to whomever knows how to make this actually work.

Answer 1

The solution is to reference the true path on Windows using the volumes: option as below:

sqldb:
    image: sqlimage 
    container_name: azure-db
    volumes:
      - "C:\\ProgramData\\Docker\\volumes\\sqldata:c:\\mssql"

To persist the data I used the following:

environment:
   - "sa_password=ddsql2017@@"
   - "ACCEPT_EULA=Y"
   - 'attach_dbs= {"dbName":"MyDb","dbFiles":"C:\\MSSQL\\MyDb.mdf","C:\\MSSQL\\MyDb.ldf"]}]'

Hope this helps someone else as many of the examples I found searching both on SO and elsewhere did not work for me, and in the Docker forums there are a lot of posts saying mounting volumes not work for Windows.