how to create a Backdoor (add a login) to ephemeral images

Question

Can anyone tell me, if this is a script that needs to be created or are these commands that need to be entered?

Now, I do know that some are commands. I have no idea what the rest are. And do I enter these from the MaaS server?

sudo apt-get install --assume-yes bzr             
bzr branch lp:~maas-maintainers/maas/backdoor-image backdoor-image    

imgs=$(echo /var/lib/maas/boot-resources/*/*/*/*/*/root-image)
for img in $imgs; do
    [ -f "$img.dist" ] || cp -a --sparse=always $img $img.dist
done    

for img in $imgs; do
    sudo ./backdoor-image/backdoor-image -v --user=backdoor --password-auth --password=ubuntu $img
done

Answer 1

That is a shell script, and it needs to be run on the machine which holds the images in /var/lib/maas/boot-resources. Just save the whole script in a file like mk-backdoor.sh, add #!/bin/bash as first line, chmod +x mk-backdoor.sh and then execute it, possibly using sudo, like sudo ./mk-backdoor.sh. Be sure to update the values for username and password first.

What the commands are doing

Install bzr without user interaction:

sudo apt-get install --assume-yes bzr

Checks out the backdoor-image code:

bzr branch lp:~maas-maintainers/maas/backdoor-image backdoor-image

Collects the paths of all images in the boot-resources folder. The * stuff is more or less telling the command to go a certain number of folders deep, and look for a file called root-image:

imgs=$(echo /var/lib/maas/boot-resources/*/*/*/*/*/root-image)

This make copies of the images, if they didn't exist yet:

for img in $imgs; do
    [ -f "$img.dist" ] || cp -a --sparse=always $img $img.dist
done

This creates the backdoor user with username "backdoor" and password="ubuntu" on each image:

for img in $imgs; do
    sudo ./backdoor-image/backdoor-image -v --user=backdoor --password-auth --password=ubuntu $img
done