From c0c9602a6be5d557bc684efc027310237a631901 Mon Sep 17 00:00:00 2001
From: Astro <astro@spaceboyz.net>
Date: Wed, 6 Nov 2019 21:44:39 +0100
Subject: [PATCH] hail: init

---
 hail.nix    | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 jobsets.nix |  8 ++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 hail.nix

diff --git a/hail.nix b/hail.nix
new file mode 100644
index 0000000..5fbf937
--- /dev/null
+++ b/hail.nix
@@ -0,0 +1,50 @@
+{ pkgs ? import <nixpkgs> { config.allowBroken = true; },
+}:
+
+with pkgs;
+let
+  physicalHost = host: {
+    inherit host;
+    configuration = <nix-config> + "/containers/${host}/configuration.nix";
+  };
+  containerHost = host: {
+    inherit host;
+    configuration = <nix-config> + "/hosts/containers/${host}/configuration.nix";
+  };
+  physicalHosts =
+    lib.mapAttrsToList (host: _: containerHost host) (
+      lib.filterAttrs (host: ty: ty == "directory" && host != "containers") (
+        builtins.readDir (<nix-config> + "/hosts")
+      ));
+  containerHosts =
+    lib.mapAttrsToList (host: _: containerHost host) (
+      lib.filterAttrs (_: ty: ty == "directory") (
+        builtins.readDir (<nix-config> + "/hosts/containers")
+      ));
+  hosts = containerHosts ++ physicalHosts;
+  hostSpec = { host, configuration }: rec {
+    # pkgs.nixos consumes a NixOS configuration. The toplevel attribute of its return set 
+    # contains the switch-to-configuration script that is also usually called by nixos-rebuild
+    config = (pkgs.nixos configuration).toplevel;
+
+    # hail expects an activator script in `$out/bin/activate`. We let it run the 
+    # switch-to-configuration script with systemd, because if hail is updated
+    # itself while switching, it would be killed during the switch
+    activator = pkgs.writeScriptBin "activate" ''
+        exec -a systemd-run ${pkgs.systemd}/bin/systemd-run \
+                --description "Hail: Activate new configuration" \
+                ${config}/bin/switch-to-configuration switch
+    '';
+  };
+in
+  builtins.listToAttrs (
+    builtins.concatMap (spec:
+      let
+        part = p: {
+          name = "${spec.host}-${p}";
+          value = (hostSpec spec).${p};
+        };
+      in
+      [ (part "config")  (part "activator") ]
+    ) hosts
+  )   
diff --git a/jobsets.nix b/jobsets.nix
index 794ae6f..17f75e4 100644
--- a/jobsets.nix
+++ b/jobsets.nix
@@ -109,6 +109,14 @@ let
         registry = "https://git.dn42.us/dn42/registry.git";
       };
     };
+
+    hail = mkJobset {
+      description = "NixOS builds for deployment through Hail";
+      nixexprpath = "hail.nix";
+      gitUrls = {
+        nix-config = "https://gitea.c3d2.de/C3D2/nix-config.git";
+      };
+    };
   };
 
   jobsetsJson = pkgs.writeText "jobsets.json" (builtins.toJSON jobsets );