forked from DGNum/colmena
223 lines
7.2 KiB
Markdown
223 lines
7.2 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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<pre>
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$ <b>colmena apply --on @tag-a</b>
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[INFO ] Enumerating nodes...
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[INFO ] Selected 7 out of 45 hosts.
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(...) ✅ 0s Successfully built
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<b>sigma</b> 🕗 7s copying path '/nix/store/h6qpk8rwm3dh3zsl1wlj1jharzf8aw9f-unit-haigha-agent.service' to 'ssh://root@sigma.redacted'...
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<b>theta</b> ✅ 7s Activation successful
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<b>gamma</b> 🕘 8s Starting...
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<b>alpha</b> ✅ 1s Activation successful
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<b>epsilon</b> 🕗 7s copying path '/nix/store/fhh4rfixny8b21l6jqzk7nqwxva5k20h-nixos-system-epsilon-20.09pre-git' to 'ssh://root@epsilon.redacted'...
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<b>beta</b> 🕗 7s removing obsolete file /boot/kernels/z28ayg10kpnlrz0s2qrb9pzv82lc20s2-initrd-linux-5.4.89-initrd
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<b>kappa</b> ✅ 2s Activation successful
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</pre>
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Colmena is still an early prototype.
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## Installation
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Colmena doesn't have a stable release yet.
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To install the latest development version to the user profile, use `default.nix`:
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```
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nix-env -if default.nix
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```
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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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# It's also possible to override the target SSH port.
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# For further customization, use the SSH_CONFIG_FILE
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# environment variable to specify a ssh_config file.
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deployment.targetPort = 1234;
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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/nix/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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## Secrets
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Colmena allows you to upload secret files to nodes that will not be stored in the Nix store.
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It implements a subset of the `deployment.keys` options supported by NixOps.
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For example, to deploy DNS-01 credentials for use with `security.acme`:
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```nix
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{
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shared-box = {
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security.acme.certs."my-site.tld".credentialsFile = "/run/keys/acme-credentials.secret";
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deployment.keys."acme-credentials.secret" = {
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# Alternatively, `text` (string) or `keyFile` (path to file)
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# may be specified.
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keyCommand = [ "vault" "read" "-field=env" "secret/dns01" ];
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destDir = "/run/keys"; # Default: /run/keys
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user = "acme"; # Default: root
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group = "nginx"; # Default: root
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mode = "0640"; # Default: 0600
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};
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# Rest of configuration...
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};
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}
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```
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Take note that if you use the default path (`/run/keys`), the secret files are only stored in-memory and will not survive reboots.
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To upload your secrets without performing a full deployment, use `colmena upload-keys`.
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## Parallelism
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Colmena is built from the ground up to support parallel deployments.
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Evaluation, build, and deployment of node configurations can happen at the same time.
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This parallelism can be controlled primarily through two flags:
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- `--limit <number>`: Number of hosts to deploy at once in the final step (pushing closures and activating new profiles).
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- `--eval-node-limit <number>`: By default, Colmena will automatically determine the maximum number of nodes to evaluate at the same time according to available RAM. This flag allows you to set the limit to a predetermined value.
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## Environment variables
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- `SSH_CONFIG_FILE`: Path to a `ssh_config` file
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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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- Error reporting is lacking.
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## Licensing
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Colmena is available under the MIT License.
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