Pmbootstrap: Improved "user" creation code

[ollieparanoid]

Follow-up to #666 and what has been discussed in the channel.
We would like to have the following changes:

• [x] user used in the build chroots should be called "build", not "user" (to avoid confusion)
• [x] ask in pmbootstrap init for the install-user, default to user
• [x] during pmbootstrap install: the install-user should be created inside the chroot, with a UID of 1000
• [x] give the install-user the normal set of "desktop" groups

Keep in mind, that a lot of --bind mounts mount stuff to /home/user, so we would need to replace the username in there.

[PabloCastellano]

I've been working in this issue today and the progress is good :tada:

However I don't know how to adjust sudoers accordingly to the username specified during the init phase.

At the moment, the user is hardcoded and I don't know how to get the username while building the postmarketos-base package nor I can use UIDs in sudoers.

[PabloCastellano]

I've also tried appending the {user} ALL=(ALL) ALL line similar to how we write /etc/os-release but since this file is only readable and writable by root, it is not straight-forward to do it from a Python function.

Any ideas?

[MartijnBraam]

You shouldn't put the username in sudoers, you the created user should be added to the wheel or sudo group and one or both of those groups should be in sudoers.

[PabloCastellano]

@MartijnBraam Oh, the sudoers file confused me and I couldn't see the standard way.

I've just pushed the last change, tried it and works for me. So it's time for review and testing.

One bad thing about this change is that you need to run some commands to set your pmbootstrap folder in a consistent state, so we will probably see people complaining about it in the channel during the week after the merge because they just updated their local repo and didn't notice about it.

These are the steps I had to run after changing branch from master:

pmb init
pmb -y zap -d -hc -p
rm -fr ~/.local/var/pmbootstrap/config_*

And these are the kind of errors that you will get if you don't run the previous commands:

(010391) [22:31:44] (native) % cd /home/build/packages/build/aarch64 && su build -c 'abuild-sign APKINDEX.tar.gz_'
Error opening key file /home/user/.abuild/user-59da88ae.rsa
139767470046092:error:02FFF002:system library:func(4095):No such file or directory:bio/bss_file.c:255:fopen('/home/user/.abuild/user-59da88ae.rsa', 'r')
139767470046092:error:20FFF002:BIO routines:CRYPTO_internal:system lib:bio/bss_file.c:257:
unable to load key file

ERROR: /home/build/packages/build/x86_64/postmarketos-base-3-r8.apk: UNTRUSTED signature

[ollieparanoid]

We have a safe upgrade path now: https://github.com/postmarketOS/pmbootstrap/pull/725/commits/a7fd434b4cc0bcca65586c2c49a2c4b64124ee16