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gentoo-install/README.md

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About gentoo-install

This script performs a reasonably minimal installation of gentoo. An EFI system is highly recommended, but legacy BIOS boot is also supported. The script supports both systemd (default) and OpenRC as the init system. The main performed steps are:

#. Partitioning #. Download & verify stage3 tarball #. Extract stage3 #. Initialize portage #. Install kernel #. Install additional software

The system will use sys-kernel/gentoo-kernel-bin, which should be suitable to boot most systems out of the box. I strongly recommend you to replace this kernel with a custom built one, when the system is functional. If you are looking for a way to detect and manage your kernel configuration, have a look at autokernel.

Quick start

Edit scripts/config.sh and execute ./install in any live system. You can review the partitioning that will be applied before anything critical is done. Afterwards, this will apply the partitioning scheme and properly install the selected stage3 gentoo system. The new system will by default use gentoo-kernel-bin as the kernel, and an initramfs generated by dracut to provide a bootable environment. The script can optionally install sshd and ansible to allow for a convenient setup of the new system afterwards.

Overview

Here is a more complete overview of what this script does:

#. Partition disks (supports gpt, raid, luks) #. Download and cryptographically verify the newest stage3 tarball #. Extract the stage3 tarball #. Sync portage tree #. Configure portage (create zz-autounmask files, configure MAKEOPTS, EMERGE_DEFAULT_OPTS) #. Select the fastest gentoo mirrors #. Configure the base system #. Install git (so you can add your portage overlays later) #. Install sys-kernel/gentoo-kernel-bin (until you replace it) #. Create efibootmgr entry or install syslinux depending on whether your system uses EFI #. Generate a basic fstab #. Ask for a root password

Also, optionally the following will be done:

  • Install sshd with secure config
  • Install dhcpcd (only for OpenRC)
  • Install ansible, create ansible user and add authorized ssh key
  • Install additional packages provided in config

Anything else is probably out of scope for this script, but you can obviously do anything later on when the system is booted. I highly recommend building a custom kernel. Have a look at the Recommendations section.

Install

Installing gentoo with this script is simple.

  1. Boot into the live system of your choice. As the script requires some utilities, I recommend using a live system where you can quickly install new software. Any Arch Linux live iso works fine.
  2. Clone this repository
  3. Edit scripts/config.sh, and particularily pay attention to the device which will be partitioned. The script will ask for confirmation before partitioning, but better be safe there.
  4. Execute ./install. The script will tell you if your live system is missing any required software.

The script should be able to run without any user supervision after partitioning, but depending on the current state of the gentoo repository you might need to intervene in case a package fails to emerge. The critical commands will ask you what to do in case of a failure.

Config

The config file scripts/config.sh allows you to adjust some parameters of the installation. The most important ones will probably be the device to partition, and the stage3 tarball name to install. By default you will get the hardened nomultilib profile without systemd.

(Optional) sshd

The script can provide a fully configured ssh daemon with reasonably good security settings. It will by default only allow ed25519 keys, restrict the key exchange algorithms, disable any password based authentication, and only allow specifically mentioned users to use ssh service (none by default).

The script will create a group named sshusers, and only users in that group will be allowed to log in via ssh. If you have added a user for yourself, you might want to add the user to that group. Be aware that root login is always denied.

(Optional) Ansible

This script can install ansible, create a system user for ansible and add an ssh key of you choice to the .authorized_keys file. This allows you to directly use ansible when the new system is up to configure the rest of the system. The ansible user will be added to the sshusers group.

(Optional) Additional packages

You can enter any amount of additional packages to be installed on the target system. These will simply be passed to a final emerge call before the script is done. Autounmasking will be done automatically.

Troubleshooting

The script checks every command for success, so if anything fails during installation, you will be given a proper message of what went wrong. Inside the chroot, most commands will be executed in some kind of try loop, and allow you to fix problems interactively with a shell, to retry, or to skip the command.

Recommendations

There are some things that you probably want to do after installing the base system, or should consider:

  • Read the news with eselect news read.
  • Use a custom kernel (config and hardening, see autokernel), and remove gentoo-kernel-bin
  • Adjust /etc/portage/make.conf
    • Set CFLAGS to -O2 -pipe -march=native for native builds
    • Set CPU_FLAGS_X86 using the cpuid2cpuflags tool
    • Set FEATURES="buildpkg" if you want to build binary packages
  • Use a safe umask like umask 0077

References