Merge #655: examples/flake.nix: minor improvements

742fd8f examples/flake.nix: add `inputs.nixpkgs` (Erik Arvstedt)
89ea349 examples/flake.nix: add comments and extra service (Erik Arvstedt)

Pull request description:

ACKs for top commit:
  jonasnick:
    ACK 742fd8f

Tree-SHA512: 7879d2c4cfa95db7b0310d402f6d8dc78fad1667f6a1021f466b8307e6f62235d113df70cc0932695fd3d80d7b141e7463e03ad45aac93c7e655c59c12c90a2f

dev/README.md

@@ -101,4 +101,5 @@ It's easiest to use an existing service as a template:
 - [flake.nix](../flake.nix): update `nixpkgs.url`
 - [cirrus.yml](../.cirrus.yml): update toplevel container -> image attribute
 - [examples/configuration.nix](../examples/configuration.nix): update `system.stateVersion`
+- [examples/flakes/flake.nix](../examples/flakes/flake.nix): update `inputs.nix-bitcoin.url`
 - Treewide: check if any `TODO-EXTERNAL` comments can be resolved

examples/flakes/flake.nix

@@ -1,13 +1,23 @@
+# This is a system configuration template that uses nix-bitcoin.
+#
+# You can adapt this to an existing system flake by copying the parts
+# relevant to nix-bitcoin.
+#
+# Make sure to check and edit all lines marked by 'FIXME:'
+
 {
   description = "A basic nix-bitcoin node";
 
   inputs.nix-bitcoin.url = "github:fort-nix/nix-bitcoin/release";
   # You can also use a version branch to track a specific NixOS release
   # inputs.nix-bitcoin.url = "github:fort-nix/nix-bitcoin/nixos-23.05";
 
-  outputs = { self, nix-bitcoin }: {
+  inputs.nixpkgs.follows = "nix-bitcoin/nixpkgs";
+  inputs.nixpkgs-unstable.follows = "nix-bitcoin/nixpkgs-unstable";
+
+  outputs = { self, nixpkgs, nix-bitcoin, ... }: {
 
-    nixosConfigurations.mynode = nix-bitcoin.inputs.nixpkgs.lib.nixosSystem {
+    nixosConfigurations.mynode = nixpkgs.lib.nixosSystem {
       system = "x86_64-linux";
       modules = [
         nix-bitcoin.nixosModules.default
@@ -23,21 +33,25 @@
           # The secrets are stored in /etc/nix-bitcoin-secrets
           nix-bitcoin.generateSecrets = true;
 
-          # Enable services.
+          # Enable some services.
           # See ../configuration.nix for all available features.
           services.bitcoind.enable = true;
+          services.clightning.enable = true;
 
           # When using nix-bitcoin as part of a larger NixOS configuration, set the following to enable
           # interactive access to nix-bitcoin features (like bitcoin-cli) for your system's main user
           nix-bitcoin.operator = {
             enable = true;
-            name = "main"; # Set this to your system's main user
+            # FIXME: Set this to your system's main user
+            name = "main";
           };
 
-          # The system's main unprivileged user. This setting is usually part of your
-          # existing NixOS configuration.
+          # The system's main unprivileged user.
+          # In an existing NixOS configuration, this setting is usually already defined.
           users.users.main = {
             isNormalUser = true;
+            # FIXME: This is unsafe. Use `hashedpassword` or `passwordFile` instead in a real
+            # deployment: https://search.nixos.org/options?show=users.users.%3Cname%3E.hashedPassword
             password = "a";
           };