examples: add krops deployment method

examples/krops/deploy.nix

@@ -0,0 +1,20 @@
+let
+  # FIXME:
+  target = "root@HOSTNAME_OR_IP_ADDRESS";
+
+  extraSources = {
+    "hardware-configuration.nix".file = toString ../hardware-configuration.nix;
+  };
+
+  krops = (import <nix-bitcoin> {}).krops;
+in
+krops.pkgs.krops.writeDeploy "deploy" {
+  inherit target;
+
+  source = import ./sources.nix { inherit extraSources krops; };
+
+  # Avoid having to create a sentinel file.
+  # Otherwise /var/src/.populate must be created on the target node to signal krops
+  # that it is allowed to deploy.
+  force = true;
+}

examples/krops/krops-configuration.nix

@@ -0,0 +1,7 @@
+# This file allows you to build your krops configuration locally
+{
+  imports = [
+    ../configuration.nix
+    <nix-bitcoin/modules/deployment/krops.nix>
+  ];
+}

examples/krops/sources.nix

@@ -0,0 +1,33 @@
+{ extraSources, krops }:
+
+krops.lib.evalSource [({
+  nixos-config.file = builtins.toFile "nixos-config" ''
+    {
+      imports = [
+        ./configuration.nix
+        <nix-bitcoin/modules/deployment/krops.nix>
+      ];
+    }
+  '';
+
+  "configuration.nix".file = toString ../configuration.nix;
+
+  # Enable `useChecksum` for sources which might be located in the nix store
+  # and which therefore might have static timestamps.
+
+  nixpkgs.file = {
+    path = toString <nixpkgs>;
+    useChecksum = true;
+  };
+
+  nix-bitcoin.file = {
+    path = toString <nix-bitcoin>;
+    useChecksum = true;
+    filters = [{
+      type = "exclude";
+      pattern = ".git";
+    }];
+  };
+
+  secrets.file = toString ../secrets;
+} // extraSources)]