SECZ-1582: Add Linux support

[rbamos]

Testing:

• Tested locally at the repo root
• Tested locally one step up from repo root (to check that utils.sh fetch works)
• Tested install on Linux box
• Tested install via Ansible; see https://github.com/panorama-ed/ansible-services/pull/5
• Started configuration, confirmed that Leapp CLI correctly communications with Leapp
• Fully configured a Leapp installation with config.sh

Core objective: make this script work on both Linux & Mac

Additional tweaks:

• Utils script is correctly fetched when not present
• Config broken out into a separate step to facilitate Ansible installation
• Non-interactive mode created to facilitate Ansible installation
• Small cleanup

[rbamos]

Unicode Quote -> ASCII quote

[eswidler]

Do we need to modify ~/.bashrc? I know it looks like we did something similar with the mac version of the script. But if we're only loading shell env vars to be able to run "brew" commands for the duration of this script, is it really necessary to modify our default shell behavior?

Could we just drop this line and use eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)" below?

[eswidler]

Also Linuxbrew is not installed currently on the eng image. How can we ensure that linuxbrew is installed?

[rbamos]

My understanding is eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)" sets up the current shell session to run brew, so you need to add it to .bashrc for it to apply to every shell session

[eswidler]

An overall comment:
One thing I'm learning is that when logged in as administrator, the home directory does not exist. So anything using ~/... would reference a non-existing dir.

How are you imagining this is run? As an AnsibleAdmin user that still has it's own /home dir & sudo-level access?

[eswidler]

Could we do sudo apt install gcc instead? If we can install gcc without brew, we may not need linuxbrew at all.

[rbamos]

We could. Actually this code is unreachable and we could just remove it outright too -- the Brew installation if check above first checks if we're on Mac OS, so if we're on Linux Brew doesn't get installed and this code doesn't run

[rbamos]

Do we need Linuxbrew for other purposes?

[eswidler]

I haven't run anything setting up the eng image that required Linuxbrew.

[eswidler]

Any apt package will be installed on the root volume and not needed if we're creating another workspace based on an image using that volume. Given that, do we need to have all of the sudo apt install PACKAGE lines we have? Could we instead rely on these packages already being available on the root volume?

EDIT: I remember that we have the uninstall process here for testing the setup from scratch. That would require reinstalling the apt packages when reinstalling. I'm ok with leaving these installation calls for now even though they're likely redundant on ansible. Seems low priority to resolve for now.

[eswidler]

Can you combine the remove and purge flags to run this once for each package?

[rbamos]

No, dpkg complains if you do

[rbamos]

An overall comment:
One thing I'm learning is that when logged in as administrator, the home directory does not exist. So anything using ~/... would reference a non-existing dir.

How are you imagining this is run? As an AnsibleAdmin user that still has it's own /home dir & sudo-level access?

This runs as the ansible user. I did add

  if [[ "$kernel_name" == "Linux" ]] && [[ ! -e "/home/$(whoami)" ]]; then
    sudo mkdir -p "/home/$(whoami)"
    if id -gn | grep 'users' > /dev/null; then
        group='users'
    else
        group=$(id -gn | cut -d ' ' -f 1)
    fi
    sudo chown -R "$(whoami):$group" "/home/$(whoami)"
  fi

But this doesn't actually get run. I could add move it to a spot where it would get run