forked from DGNum/colmena
152 lines
4.4 KiB
Markdown
152 lines
4.4 KiB
Markdown
# Colmena
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Colmena is a simple, stateless NixOS deployment tool modeled after [NixOps](https://github.com/NixOS/nixops) and [Morph](https://github.com/DBCDK/morph), written in Rust.
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It's a thin wrapper over Nix commands like `nix-instantiate` and `nix-copy-closure`, and supports parallel deployment.
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Colmena is still an early prototype.
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## Tutorial
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Enter a shell with `colmena` with:
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```
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nix-shell
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```
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Colmena should work with your existing NixOps and Morph configurations with minimal modification.
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Here is a sample `hive.nix` with two nodes, with some common configurations applied to both nodes:
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```nix
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{
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meta = {
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# Override to pin the Nixpkgs version (recommended). This option
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# accepts one of the following:
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# - A path to a Nixpkgs checkout
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# - The Nixpkgs lambda (e.g., import <nixpkgs>)
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# - An initialized Nixpkgs attribute set
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nixpkgs = <nixpkgs>;
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# You can also override Nixpkgs by node!
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nodeNixpkgs = {
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node-b = ./another-nixos-checkout;
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};
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};
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defaults = { pkgs, ... }: {
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# This module will be imported by all hosts
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environment.systemPackages = with pkgs; [
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vim wget curl
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];
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};
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host-a = { name, nodes, ... }: {
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# The name and nodes parameters are supported in Colmena,
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# allowing you to reference configurations in other nodes.
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networking.hostName = name;
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time.timeZone = nodes.host-b.config.time.timeZone;
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boot.loader.grub.device = "/dev/sda";
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fileSystems."/" = {
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device = "/dev/sda1";
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fsType = "ext4";
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};
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};
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host-b = {
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# Like NixOps and Morph, Colmena will attempt to connect to
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# the remote host using the attribute name by default. You
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# can override it like:
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deployment.targetHost = "host-b.mydomain.tld";
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time.timeZone = "America/Los_Angeles";
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boot.loader.grub.device = "/dev/sda";
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fileSystems."/" = {
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device = "/dev/sda1";
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fsType = "ext4";
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};
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};
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}
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```
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The full set of options can be found at `src/eval.nix`.
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Run `colmena build` in the same directory to build the configuration, or do `colmena apply` to deploy it to all nodes.
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## `colmena introspect`
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Sometimes you may want to extract values from your Hive configuration for consumption in another program (e.g., [OctoDNS](https://github.com/octodns/octodns)).
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To do that, create a `.nix` file with a lambda:
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```nix
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{ nodes, pkgs, lib, ... }:
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# Feels like a NixOS module - But you can return any JSON-serializable value
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lib.attrsets.mapAttrs (k: v: v.config.deployment.targetHost) nodes
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```
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Then you can evaluate with:
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```
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colmena introspect your-lambda.nix
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```
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## `colmena apply-local`
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For some machines, you may still want to stick with the manual `nixos-rebuild`-type of workflow.
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Colmena allows you to build and activate configurations on the host running Colmena itself, provided that:
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1. The node must be running NixOS.
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1. The node must have `deployment.allowLocalDeployment` set to `true`.
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1. The node's _attribute name_ must match the hostname of the machine.
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If you invoke `apply-local` with `--sudo`, Colmena will attempt to elevate privileges with `sudo` if it's not run as root.
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You may also find it helpful to set `deployment.targetHost` to `null` if you don't intend to deploy to the host via SSH.
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As an example, the following `hive.nix` includes a node (`laptop`) that is meant to be only deployed with `apply-local`:
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```nix
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{
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meta = {
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nixpkgs = ./deps/nixpkgs-stable;
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# I'd like to use the unstable version of Nixpkgs on
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# my desktop machines.
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nodeNixpkgs = {
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laptop = ./deps/nixpkgs-unstable;
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};
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};
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# This attribute name must match the output of `hostname` on your machine
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laptop = { name, nodes, ... }: {
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networking.hostName = "laptop";
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deployment = {
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# Allow local deployment with `colmena apply-local`
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allowLocalDeployment = true;
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# Disable SSH deployment. This node will be skipped in a
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# normal`colmena apply`.
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targetHost = null;
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};
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# Rest of configuration...
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};
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server-a = { pkgs, ... }: {
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# This node will use the default Nixpkgs checkout specified
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# in `meta.nixpkgs`.
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# Rest of configuration...
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};
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}
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```
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On `laptop`, run `colmena apply-local --sudo` to activate the configuration.
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## Current limitations
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- It's required to use SSH keys to log into the remote hosts, and interactive authentication will not work.
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- There is no option to override SSH or `nix-copy-closure` options.
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- Error reporting is lacking.
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## Licensing
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Colmena is available under the MIT License.
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