Restrict fileset necessary for deployment tests (#450)

Now that we won't depend on the flake.nix anymore, we won't depend on all the flake-part.nix files (necessary to evaluate flake.nix) and all the files they depend on etc., so the Nix dependencies of the tests will be drastically reduced, and I will be able to leverage that by introducing a more subtle src. This will make the test not need to re-run if only things outside that reduced src changed (and the previous run is in the Nix store).

Reviewed-on: Fediversity/Fediversity#450
Reviewed-by: kiara Grouwstra <kiara@procolix.eu>
Reviewed-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-authored-by: Nicolas “Niols” Jeannerod <nicolas.jeannerod@moduscreate.com>
Co-committed-by: Nicolas “Niols” Jeannerod <nicolas.jeannerod@moduscreate.com>

deployment/check/basic/nixosTest.nix

@@ -1,10 +1,15 @@
-{ inputs, ... }:
+{ inputs, lib, ... }:
 
 {
   _class = "nixosTest";
 
   name = "deployment-basic";
 
+  sourceFileset = lib.fileset.unions [
+    ./constants.nix
+    ./deployment.nix
+  ];
+
   nodes.deployer =
     { pkgs, ... }:
     {

deployment/check/cli/nixosTest.nix

@@ -1,4 +1,9 @@
-{ inputs, hostPkgs, ... }:
+{
+  inputs,
+  hostPkgs,
+  lib,
+  ...
+}:
 
 let
   ## Some places need a dummy file that will in fact never be used. We create
@@ -11,6 +16,21 @@ in
 
   name = "deployment-cli";
 
+  sourceFileset = lib.fileset.unions [
+    ./constants.nix
+    ./deployments.nix
+
+    # REVIEW: I would like to be able to grab all of `/deployment` minus
+    # `/deployment/check`, but I can't because there is a bunch of other files
+    # in `/deployment`. Maybe we can think of a reorg making things more robust
+    # here? (comment also in panel test)
+    ../../default.nix
+    ../../options.nix
+    ../../configuration.sample.json
+
+    ../../../services/fediversity
+  ];
+
   nodes.deployer =
     { pkgs, ... }:
     {

deployment/check/common/nixosTest.nix

@@ -13,6 +13,7 @@ let
     toJSON
     ;
   inherit (lib)
+    types
     fileset
     mkOption
     genAttrs
@@ -27,14 +28,6 @@ let
 
   forConcat = xs: f: concatStringsSep "\n" (map f xs);
 
-  ## The whole repository, with the flake at its root.
-  ## FIXME: We could probably have fileset be the union of ./. with flake.nix
-  ## and flake.lock - I doubt we need anything else.
-  src = fileset.toSource {
-    fileset = config.pathToRoot;
-    root = config.pathToRoot;
-  };
-
   ## We will need to override some inputs by the empty flake, so we make one.
   emptyFlake = runCommandNoCC "empty-flake" { } ''
     mkdir $out
@@ -53,9 +46,39 @@ in
     ## FIXME: I wish I could just use `testScript` but with something like
     ## `mkOrder` to put this module's string before something else.
     extraTestScript = mkOption { };
+
+    sourceFileset = mkOption {
+      ## REVIEW: Upstream to nixpkgs?
+      type = types.mkOptionType {
+        name = "fileset";
+        description = "fileset";
+        descriptionClass = "noun";
+        check = (x: (builtins.tryEval (fileset.unions [ x ])).success);
+        merge = (_: defs: fileset.unions (map (x: x.value) defs));
+      };
+      description = ''
+        A fileset that will be copied to the deployer node in the current
+        working directory. This should contain all the files that are
+        necessary to run that particular test, such as the NixOS
+        modules necessary to evaluate a deployment.
+      '';
+    };
   };
 
   config = {
+    sourceFileset = fileset.unions [
+      # NOTE: not the flake itself; it will be overridden.
+      ../../../mkFlake.nix
+      ../../../flake.lock
+      ../../../npins
+
+      ./sharedOptions.nix
+      ./targetNode.nix
+      ./targetResource.nix
+
+      (config.pathToCwd + "/flake-under-test.nix")
+    ];
+
     acmeNodeIP = config.nodes.acme.networking.primaryIPAddress;
 
     nodes =
@@ -103,8 +126,16 @@ in
         ${n}.wait_for_unit("multi-user.target")
       '')}
 
+      ## A subset of the repository that is necessary for this test. It will be
+      ## copied inside the test. The smaller this set, the faster our CI, because we
+      ## won't need to re-run when things change outside of it.
       with subtest("Unpacking"):
-        deployer.succeed("cp -r --no-preserve=mode ${src}/* .")
+        deployer.succeed("cp -r --no-preserve=mode ${
+          fileset.toSource {
+            root = ../../..;
+            fileset = config.sourceFileset;
+          }
+        }/* .")
 
       with subtest("Configure the network"):
         ${forConcat config.targetMachines (

deployment/check/panel/nixosTest.nix

@@ -125,6 +125,20 @@ in
 
   name = "deployment-panel";
 
+  sourceFileset = lib.fileset.unions [
+    ./constants.nix
+    ./deployment.nix
+
+    # REVIEW: I would like to be able to grab all of `/deployment` minus
+    # `/deployment/check`, but I can't because there is a bunch of other files
+    # in `/deployment`. Maybe we can think of a reorg making things more robust
+    # here? (comment also in CLI test)
+    ../../default.nix
+    ../../options.nix
+
+    ../../../services/fediversity
+  ];
+
   ## The panel's module sets `nixpkgs.overlays` which clashes with
   ## `pkgsReadOnly`. We disable it here.
   node.pkgsReadOnly = false;