From 02d319acf615252f080c08f0593eab41a7ef2c2d Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Sun, 29 Sep 2019 23:44:53 +0200
Subject: [PATCH] Expose composition to services

---
 doc/manual/default.nix                            | 2 +-
 src/nix/eval-service.nix                          | 5 +++--
 src/nix/modules/composition/docker-compose.nix    | 6 +++++-
 src/nix/modules/service/{host.nix => context.nix} | 6 ++++++
 4 files changed, 15 insertions(+), 4 deletions(-)
 rename src/nix/modules/service/{host.nix => context.nix} (56%)

diff --git a/doc/manual/default.nix b/doc/manual/default.nix
index ff2096c..03522ab 100644
--- a/doc/manual/default.nix
+++ b/doc/manual/default.nix
@@ -69,7 +69,7 @@ let
             declarations = map (d: "src/nix" + (lib.strings.removePrefix (toString ${src}) (toString d))) opt.declarations;
           };
           inherit (pkgs) lib;
-          composition = pkgs.callPackage ${src}/eval-service.nix {} { modules = []; host = {}; name = abort "The manual's service options section must not depend on the service name."; };
+          composition = pkgs.callPackage ${src}/eval-service.nix {} { modules = []; host = {}; name = abort "The manual's service options section must not depend on the service name."; composition = abort "The manual's service options must not depend on the composition."; };
       in map fixPaths (lib.filter (opt: opt.visible && !opt.internal) (lib.optionAttrSetToDocList composition.options))
     '';
   };
diff --git a/src/nix/eval-service.nix b/src/nix/eval-service.nix
index cb866ba..2ab731b 100644
--- a/src/nix/eval-service.nix
+++ b/src/nix/eval-service.nix
@@ -1,6 +1,6 @@
 { lib, pkgs, ... }:
 
-{ modules, host, name }:
+{ modules, host, name, composition }:
 let
   composite = lib.evalModules {
     check = true;
@@ -13,7 +13,7 @@ let
     ./modules/service/docker-compose-service.nix
     ./modules/service/extended-info.nix
     ./modules/service/host-store.nix
-    ./modules/service/host.nix
+    ./modules/service/context.nix
     ./modules/service/image.nix
     ./modules/service/nixos.nix
     ./modules/service/nixos-init.nix
@@ -25,6 +25,7 @@ let
     config._module.args.pkgs = lib.mkForce pkgs;
     config.host = host;
     config.service.name = name;
+    config.composition = composition;
   };
 
 in
diff --git a/src/nix/modules/composition/docker-compose.nix b/src/nix/modules/composition/docker-compose.nix
index c223f68..1891bbf 100644
--- a/src/nix/modules/composition/docker-compose.nix
+++ b/src/nix/modules/composition/docker-compose.nix
@@ -11,7 +11,11 @@
  */
 { pkgs, lib, config, ... }:
 let
-  evalService = name: modules: pkgs.callPackage ../../eval-service.nix {} { inherit name modules; inherit (config) host; };
+  evalService = name: modules: pkgs.callPackage ../../eval-service.nix {} {
+    inherit name modules;
+    inherit (config) host;
+    composition = config;
+  };
 
 in
 {
diff --git a/src/nix/modules/service/host.nix b/src/nix/modules/service/context.nix
similarity index 56%
rename from src/nix/modules/service/host.nix
rename to src/nix/modules/service/context.nix
index 3ba2ee8..10854e2 100644
--- a/src/nix/modules/service/host.nix
+++ b/src/nix/modules/service/context.nix
@@ -7,5 +7,11 @@
         The composition-level host option values.
       '';
     };
+    composition = lib.mkOption {
+      type = lib.types.attrs;
+      description = ''
+        The composition configuration.
+      '';
+    };
   };
 }