Added the cloud-init service

nixos/modules/module-list.nix

@@ -304,6 +304,7 @@
   ./services/security/torify.nix
   ./services/security/tor.nix
   ./services/security/torsocks.nix
+  ./services/system/cloud-init.nix
   ./services/system/dbus.nix
   ./services/system/kerberos.nix
   ./services/system/nscd.nix

nixos/modules/services/system/cloud-init.nix

@@ -0,0 +1,152 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let cfg = config.services.cloud-init;
+    path = with pkgs; [ cloud-init nettools utillinux e2fsprogs shadow dmidecode openssh ];
+    configFile = pkgs.writeText "cloud-init.cfg" ''
+users:
+   - root
+
+disable_root: false
+preserve_hostname: false
+
+cloud_init_modules:
+ - migrator
+ - seed_random
+ - bootcmd
+ - write-files
+ - growpart
+ - resizefs
+ - set_hostname
+ - update_hostname
+ - update_etc_hosts
+ - ca-certs
+ - rsyslog
+ - users-groups
+
+cloud_config_modules:
+ - emit_upstart
+ - disk_setup
+ - mounts
+ - ssh-import-id
+ - set-passwords
+ - timezone
+ - disable-ec2-metadata
+ - runcmd
+ - ssh
+
+cloud_final_modules:
+ - rightscale_userdata
+ - scripts-vendor
+ - scripts-per-once
+ - scripts-per-boot
+ - scripts-per-instance
+ - scripts-user
+ - ssh-authkey-fingerprints
+ - keys-to-console
+ - phone-home
+ - final-message
+ - power-state-change
+'';
+in
+{
+  options = {
+
+    services.cloud-init = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Enable the cloud-init service. This services reads
+          configuration metadata in a cloud environment and configures
+          the machine according to this metadata.
+
+          This configuration is not completely compatible with the
+          NixOS way of doing configuration, as configuration done by
+          cloud-init might be overriden by a subsequent nixos-rebuild
+          call. However, some parts of cloud-init fall outside of
+          NixOS's responsibility, like filesystem resizing and ssh
+          public key provisioning, and cloud-init is useful for that
+          parts. Thus, be wary that using cloud-init in NixOS might
+          come as some cost.
+        '';
+      };
+
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+
+    systemd.services.cloud-init-local =
+      { description = "Initial cloud-init job (pre-networking)";
+        wantedBy = [ "multi-user.target" ];
+        wants = [ "local-fs.target" ];
+        after = [ "local-fs.target" ];
+        path = path;
+        serviceConfig =
+          { Type = "oneshot";
+            ExecStart = "${pkgs.cloud-init}/bin/cloud-init -f ${configFile} init --local";
+            RemainAfterExit = "yes";
+            TimeoutSec = "0";
+            StandardOutput = "journal+console";
+          };
+      };
+
+    systemd.services.cloud-init =
+      { description = "Initial cloud-init job (metadata service crawler)";
+        wantedBy = [ "multi-user.target" ];
+        wants = [ "local-fs.target" "cloud-init-local.service" "sshd.service" "sshd-keygen.service" ];
+        after = [ "local-fs.target" "network.target" "cloud-init-local.service" ];
+        before = [ "sshd.service" "sshd-keygen.service" ];
+        requires = [ "network.target "];
+        path = path;
+        serviceConfig =
+          { Type = "oneshot";
+            ExecStart = "${pkgs.cloud-init}/bin/cloud-init -f ${configFile} init";
+            RemainAfterExit = "yes";
+            TimeoutSec = "0";
+            StandardOutput = "journal+console";
+          };
+      };
+
+    systemd.services.cloud-config =
+      { description = "Apply the settings specified in cloud-config";
+        wantedBy = [ "multi-user.target" ];
+        wants = [ "network.target" ];
+        after = [ "network.target" "syslog.target" "cloud-config.target" ];
+
+        path = path;
+        serviceConfig =
+          { Type = "oneshot";
+            ExecStart = "${pkgs.cloud-init}/bin/cloud-init -f ${configFile} modules --mode=config";
+            RemainAfterExit = "yes";
+            TimeoutSec = "0";
+            StandardOutput = "journal+console";
+          };
+      };
+
+    systemd.services.cloud-final =
+      { description = "Execute cloud user/final scripts";
+        wantedBy = [ "multi-user.target" ];
+        wants = [ "network.target" ];
+        after = [ "network.target" "syslog.target" "cloud-config.service" "rc-local.service" ];
+        requires = [ "cloud-config.target" ];
+        path = path;
+        serviceConfig =
+          { Type = "oneshot";
+            ExecStart = "${pkgs.cloud-init}/bin/cloud-init -f ${configFile} modules --mode=final";
+            RemainAfterExit = "yes";
+            TimeoutSec = "0";
+            StandardOutput = "journal+console";
+          };
+      };
+
+    systemd.targets.cloud-config =
+      { description = "Cloud-config availability";
+        requires = [ "cloud-init-local.service" "cloud-init.service" ];
+      };
+  };
+}