Change docker-machine docker user default password

Question

I'm using docker-machine to configure a production docker environment also with docker swarm. When you create a new docker-machine the docker user default password is tcuser. You'll need this to link your machines from other sites configuring the .ssh/authorized_keys file.

When you begin launching services, you'll want to change the default docker user password, so you can protect your systems from unauthorized access (docker user is a sudoer!), but when you launch a passwd command and reboot the machine, you'll see your changes have been reverted.

The question: Where or how should I change the docker user password to keep the changes between reboots?

Answer 1

Boot2docker is an ISO image that starts your light machine with the docker daemon runing on it. It has two directories where it stores persistent information:

• /var/lib/booot2docker: to store operative system configurations.
• /var/lib/docker: to store docker daemon configurations.

These two folders are populated to tmpfs filesystems during startup, so it's here where you have to make your changes.

So, to change the password you have to login into the machine executing docker-machine ssh YourMachine. Then change the file /var/lib/boot2docker/profile and add this line to it:

echo "docker:YourNewPassword"|sudo chpasswd

Then you have to reboot the machine, for example, launching docker-machine restart YourMachine from your host. This way, the profile script will be executed on startup and it will reset your password to the one you choose on every reboot.

You can check that the old password tcuser no longer works, as expected.

P.S.: I still don't understand how it's been so difficult to find a solution to this issue in stackoverflow or Googling away... I really think it's important enough.