Add an arbitrary mount point to Docker Toolbox containers

docker-toolbox.md

• Add a "Shared Folder" to the default docker VirtualBox virtual machine. There is already a shared folder C:\Users. Add, for example, share host C:\Temp directory as c/Temp.
• Add the following code to C:\Program Files\Docker Toolbox\start.sh:

init_mounts() {
    ${DOCKER_MACHINE} ssh ${VM} sudo 'mkdir /c/Temp'
    ${DOCKER_MACHINE} ssh ${VM} sudo 'chown docker:staff /c/Temp'
    ${DOCKER_MACHINE} ssh ${VM} sudo 'mount -t vboxsf c/Temp /c/Temp'
}
export -f init_mounts

if [ "${VM_STATUS}" != "Running" ]; then
    init_mounts
fi

• To verify that the mount point is created successfully, run this in the Docker Terminal:

$ docker-machine ssh default 'tail -1 /etc/mtab'
c/Temp /c/Temp vboxsf rw,nodev,relatime 0 0