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diff --git a/nixos/doc/manual/installation/installing-from-other-distro.section.md b/nixos/doc/manual/installation/installing-from-other-distro.section.md new file mode 100644 index 00000000000..d9060eb89c3 --- /dev/null +++ b/nixos/doc/manual/installation/installing-from-other-distro.section.md @@ -0,0 +1,279 @@ +# Installing from another Linux distribution {#sec-installing-from-other-distro} + +Because Nix (the package manager) & Nixpkgs (the Nix packages +collection) can both be installed on any (most?) Linux distributions, +they can be used to install NixOS in various creative ways. You can, for +instance: + +1. Install NixOS on another partition, from your existing Linux + distribution (without the use of a USB or optical device!) + +1. Install NixOS on the same partition (in place!), from your existing + non-NixOS Linux distribution using `NIXOS_LUSTRATE`. + +1. Install NixOS on your hard drive from the Live CD of any Linux + distribution. + +The first steps to all these are the same: + +1. Install the Nix package manager: + + Short version: + + ```ShellSession + $ curl -L https://nixos.org/nix/install | sh + $ . $HOME/.nix-profile/etc/profile.d/nix.sh # …or open a fresh shell + ``` + + More details in the [ Nix + manual](https://nixos.org/nix/manual/#chap-quick-start) + +1. Switch to the NixOS channel: + + If you\'ve just installed Nix on a non-NixOS distribution, you will + be on the `nixpkgs` channel by default. + + ```ShellSession + $ nix-channel --list + nixpkgs https://nixos.org/channels/nixpkgs-unstable + ``` + + As that channel gets released without running the NixOS tests, it + will be safer to use the `nixos-*` channels instead: + + ```ShellSession + $ nix-channel --add https://nixos.org/channels/nixos-version nixpkgs + ``` + + You may want to throw in a `nix-channel --update` for good measure. + +1. Install the NixOS installation tools: + + You\'ll need `nixos-generate-config` and `nixos-install`, but this + also makes some man pages and `nixos-enter` available, just in case + you want to chroot into your NixOS partition. NixOS installs these + by default, but you don\'t have NixOS yet.. + + ```ShellSession + $ nix-env -f '<nixpkgs>' -iA nixos-install-tools + ``` + +1. ::: {.note} + The following 5 steps are only for installing NixOS to another + partition. For installing NixOS in place using `NIXOS_LUSTRATE`, + skip ahead. + ::: + + Prepare your target partition: + + At this point it is time to prepare your target partition. Please + refer to the partitioning, file-system creation, and mounting steps + of [](#sec-installation) + + If you\'re about to install NixOS in place using `NIXOS_LUSTRATE` + there is nothing to do for this step. + +1. Generate your NixOS configuration: + + ```ShellSession + $ sudo `which nixos-generate-config` --root /mnt + ``` + + You\'ll probably want to edit the configuration files. Refer to the + `nixos-generate-config` step in [](#sec-installation) for more + information. + + Consider setting up the NixOS bootloader to give you the ability to + boot on your existing Linux partition. For instance, if you\'re + using GRUB and your existing distribution is running Ubuntu, you may + want to add something like this to your `configuration.nix`: + + ```nix + boot.loader.grub.extraEntries = '' + menuentry "Ubuntu" { + search --set=ubuntu --fs-uuid 3cc3e652-0c1f-4800-8451-033754f68e6e + configfile "($ubuntu)/boot/grub/grub.cfg" + } + ''; + ``` + + (You can find the appropriate UUID for your partition in + `/dev/disk/by-uuid`) + +1. Create the `nixbld` group and user on your original distribution: + + ```ShellSession + $ sudo groupadd -g 30000 nixbld + $ sudo useradd -u 30000 -g nixbld -G nixbld nixbld + ``` + +1. Download/build/install NixOS: + + ::: {.warning} + Once you complete this step, you might no longer be able to boot on + existing systems without the help of a rescue USB drive or similar. + ::: + + ::: {.note} + On some distributions there are separate PATHS for programs intended + only for root. In order for the installation to succeed, you might + have to use `PATH="$PATH:/usr/sbin:/sbin"` in the following command. + ::: + + ```ShellSession + $ sudo PATH="$PATH" NIX_PATH="$NIX_PATH" `which nixos-install` --root /mnt + ``` + + Again, please refer to the `nixos-install` step in + [](#sec-installation) for more information. + + That should be it for installation to another partition! + +1. Optionally, you may want to clean up your non-NixOS distribution: + + ```ShellSession + $ sudo userdel nixbld + $ sudo groupdel nixbld + ``` + + If you do not wish to keep the Nix package manager installed either, + run something like `sudo rm -rv ~/.nix-* /nix` and remove the line + that the Nix installer added to your `~/.profile`. + +1. ::: {.note} + The following steps are only for installing NixOS in place using + `NIXOS_LUSTRATE`: + ::: + + Generate your NixOS configuration: + + ```ShellSession + $ sudo `which nixos-generate-config` --root / + ``` + + Note that this will place the generated configuration files in + `/etc/nixos`. You\'ll probably want to edit the configuration files. + Refer to the `nixos-generate-config` step in + [](#sec-installation) for more information. + + You\'ll likely want to set a root password for your first boot using + the configuration files because you won\'t have a chance to enter a + password until after you reboot. You can initalize the root password + to an empty one with this line: (and of course don\'t forget to set + one once you\'ve rebooted or to lock the account with + `sudo passwd -l root` if you use `sudo`) + + ```nix + users.users.root.initialHashedPassword = ""; + ``` + +1. Build the NixOS closure and install it in the `system` profile: + + ```ShellSession + $ nix-env -p /nix/var/nix/profiles/system -f '<nixpkgs/nixos>' -I nixos-config=/etc/nixos/configuration.nix -iA system + ``` + +1. Change ownership of the `/nix` tree to root (since your Nix install + was probably single user): + + ```ShellSession + $ sudo chown -R 0.0 /nix + ``` + +1. Set up the `/etc/NIXOS` and `/etc/NIXOS_LUSTRATE` files: + + `/etc/NIXOS` officializes that this is now a NixOS partition (the + bootup scripts require its presence). + + `/etc/NIXOS_LUSTRATE` tells the NixOS bootup scripts to move + *everything* that\'s in the root partition to `/old-root`. This will + move your existing distribution out of the way in the very early + stages of the NixOS bootup. There are exceptions (we do need to keep + NixOS there after all), so the NixOS lustrate process will not + touch: + + - The `/nix` directory + + - The `/boot` directory + + - Any file or directory listed in `/etc/NIXOS_LUSTRATE` (one per + line) + + ::: {.note} + Support for `NIXOS_LUSTRATE` was added in NixOS 16.09. The act of + \"lustrating\" refers to the wiping of the existing distribution. + Creating `/etc/NIXOS_LUSTRATE` can also be used on NixOS to remove + all mutable files from your root partition (anything that\'s not in + `/nix` or `/boot` gets \"lustrated\" on the next boot. + + lustrate /ˈlʌstreɪt/ verb. + + purify by expiatory sacrifice, ceremonial washing, or some other + ritual action. + ::: + + Let\'s create the files: + + ```ShellSession + $ sudo touch /etc/NIXOS + $ sudo touch /etc/NIXOS_LUSTRATE + ``` + + Let\'s also make sure the NixOS configuration files are kept once we + reboot on NixOS: + + ```ShellSession + $ echo etc/nixos | sudo tee -a /etc/NIXOS_LUSTRATE + ``` + +1. Finally, move the `/boot` directory of your current distribution out + of the way (the lustrate process will take care of the rest once you + reboot, but this one must be moved out now because NixOS needs to + install its own boot files: + + ::: {.warning} + Once you complete this step, your current distribution will no + longer be bootable! If you didn\'t get all the NixOS configuration + right, especially those settings pertaining to boot loading and root + partition, NixOS may not be bootable either. Have a USB rescue + device ready in case this happens. + ::: + + ```ShellSession + $ sudo mv -v /boot /boot.bak && + sudo /nix/var/nix/profiles/system/bin/switch-to-configuration boot + ``` + + Cross your fingers, reboot, hopefully you should get a NixOS prompt! + +1. If for some reason you want to revert to the old distribution, + you\'ll need to boot on a USB rescue disk and do something along + these lines: + + ```ShellSession + # mkdir root + # mount /dev/sdaX root + # mkdir root/nixos-root + # mv -v root/* root/nixos-root/ + # mv -v root/nixos-root/old-root/* root/ + # mv -v root/boot.bak root/boot # We had renamed this by hand earlier + # umount root + # reboot + ``` + + This may work as is or you might also need to reinstall the boot + loader. + + And of course, if you\'re happy with NixOS and no longer need the + old distribution: + + ```ShellSession + sudo rm -rf /old-root + ``` + +1. It\'s also worth noting that this whole process can be automated. + This is especially useful for Cloud VMs, where provider do not + provide NixOS. For instance, + [nixos-infect](https://github.com/elitak/nixos-infect) uses the + lustrate process to convert Digital Ocean droplets to NixOS from + other distributions automatically. |