Bitcoin Core NixOS Dev configuration

Files

• configuration.nix - General system configuration
• disk-config.nix - Disk layout
• flake.nix - Flake configuration
• home-manager/home.nix - Home manager setup
• vars.nix - User-specific variables

Quickstart

If you're familiar with nix deployment, this is the order of operations, otherwise see the more detailed Setup below:

1. Modify vars in vars.nix
2. Create a suitable disko disk-config in disk-config.nix
3. Deploy to a remote host with nix-shell -p nixos-anywhere --run "nixos-anywhere --flake .#nixos <hostname>"
4. Login to remote host as the user and:

   git clone https://github.com/bitcoin/bitcoin ~/bitcoin
   cd ~/setup
   just setup ~/bitcoin
   cd ~/bitcoin

5. A bitcoin dev shell will be loaded from ~/flakes/bitcoin automatically on entering the ~/bitcoin directory.
6. Neovim (nvim) will be configured with LSPs, completion etc. automatically.

Setup

You'll need nix installed locally, and it will need nix-command and flakes enabled. This can be achieved by adding the following to /etc/nix/nix.conf:

$ sudoedit /etc/nix/nix.conf

# add this line to the file
experimental-features = nix-command flakes

After adding this line, restart the nix daemon:

# Linux
sudo systemctl restart nix-daemon
# MacOS
sudo launchctl stop org.nixos.nix-daemon
sudo launchctl start org.nixos.nix-daemon

Usage

1. Modify the following lines in vars.nix to your own values, e.g.:

   username = "will";
   sshKey = "ssh-ed25519 <sshkey> [email protected]";

2. Configure the disk layout for the remote machine.

   Generally, this involves SSHing into the target machine and checking which disks are available:

   ssh <hostname>
   
   # On host
   ❯ lsblk
   NAME          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
   sda             8:0    0 38.1G  0 disk
   ├─sda1          8:1    0    1M  0 part
   ├─sda2          8:2    0  500M  0 part /boot
   └─sda3          8:3    0 37.7G  0 part
     └─pool-root 254:0    0 37.7G  0 lvm  /nix/store
                                          /
   sr0            11:0    1 1024M  0 rom

   With this information you can configure the ./disk-config.nix file appropriately.

   Currently this is confgiured to use a standard GPT (GUID Partition Table) that is compatible with both EFI and BIOS systems and mounts the disk as /dev/sda. You may need to adjust /dev/sda to match the correct disk on your machine.

   If this setup does not match your requirements, you can choose an example that better suits your disk layout from the disko examples. For more detailed information, refer to the disko documentation.

3. Lock your Flake

   nix flake lock
   

   This will download your flake dependencies and make a flake.lock file that describes how to reproducibly build your system.

   Optionally, you can commit these files to a repo such as Github.

4. Connectivity to the Target Machine

   nixos-anywhere will create a temporary SSH key to use for the installation. If your SSH key is not found, you will be asked for your password. If you are using a non-root user, you must have access to sudo without a password. To avoid SSH password prompts, set the SSHPASS environment variable to your password and add --env-password to the nixos-anywhere command. If providing a specific SSH key through -i (identity_file), this key will then be used for the installation and no temporary SSH key will be created.

   It's highly recommended to use an ~/.ssh/config entry to configure ssh access to the host:

   cat ~/.ssh/config
   
   Host my-hostname
    HostName 123.456.789.1
    Port 22
    User root
    IdentityFile /path/to/my/ssh/key.pub
   

   This makes deploying and (remote) switching with the justfile much smoother.

5. Deploy

   Run the following to deploy using nixos-anywhere:

   just deploy <hostname>
   # or
   nix-shell -p nixos-anywhere --run "nixos-anywhere --flake .#nixos <hostname>"

6. Updating a deployed system

   1. Locally

      Ideally at this point you would commit this directory to a git repo, and clone it on the host. Then (locally on the host) you would make your changes, add them to git (staging area or committed) and run nixos-rebuild switch.

      On this host:

      git add . && git commit -m "initial deployment"
      # Push to https://github.com/name/repo

      ... and on the remote host:

      git clone https://github.com/name/repo ~/nixos-config && cd ~/nixos-config
      
      just switch
      # or
      sudo nix-shell -p nixos-rebuild --run "nixos-rebuild switch --flake ."

   2. Remotely

      It's not best practice, but you can make more changes here, add them to git, and run the appropriate justfile helper command to apply them remotely, but this is not recommended:

      just switch-remote <hostname>