Factor the NixOS channel building code out into its own file, so I can use it elsewhere

nixos/lib/make-channel.nix

@@ -0,0 +1,31 @@
+{ pkgs, nixpkgs, version, versionSuffix }:
+
+pkgs.releaseTools.makeSourceTarball {
+  name = "nixos-channel";
+
+  src = nixpkgs;
+
+  officialRelease = false; # FIXME: fix this in makeSourceTarball
+  inherit version versionSuffix;
+
+  buildInputs = [ pkgs.nixUnstable ];
+
+  expr = builtins.readFile ./channel-expr.nix;
+
+  distPhase = ''
+    rm -rf .git
+    echo -n $VERSION_SUFFIX > .version-suffix
+    echo -n ${nixpkgs.rev or nixpkgs.shortRev} > .git-revision
+    releaseName=nixos-$VERSION$VERSION_SUFFIX
+    mkdir -p $out/tarballs
+    mkdir ../$releaseName
+    cp -prd . ../$releaseName/nixpkgs
+    chmod -R u+w ../$releaseName
+    ln -s nixpkgs/nixos ../$releaseName/nixos
+    echo "$expr" > ../$releaseName/default.nix
+    NIX_STATE_DIR=$TMPDIR nix-env -f ../$releaseName/default.nix -qaP --meta --xml \* > /dev/null
+    cd ..
+    chmod -R u+w $releaseName
+    tar cfJ $out/tarballs/$releaseName.tar.xz $releaseName
+  '';
+}

nixos/release.nix

@@ -93,37 +93,7 @@ let
 
 in rec {
 
-  channel =
-    pkgs.releaseTools.makeSourceTarball {
-      name = "nixos-channel";
-
-      src = nixpkgs;
-
-      officialRelease = false; # FIXME: fix this in makeSourceTarball
-      inherit version versionSuffix;
-
-      buildInputs = [ pkgs.nixUnstable ];
-
-      expr = builtins.readFile lib/channel-expr.nix;
-
-      distPhase = ''
-        rm -rf .git
-        echo -n $VERSION_SUFFIX > .version-suffix
-        echo -n ${nixpkgs.rev or nixpkgs.shortRev} > .git-revision
-        releaseName=nixos-$VERSION$VERSION_SUFFIX
-        mkdir -p $out/tarballs
-        mkdir ../$releaseName
-        cp -prd . ../$releaseName/nixpkgs
-        chmod -R u+w ../$releaseName
-        ln -s nixpkgs/nixos ../$releaseName/nixos
-        echo "$expr" > ../$releaseName/default.nix
-        NIX_STATE_DIR=$TMPDIR nix-env -f ../$releaseName/default.nix -qaP --meta --xml \* > /dev/null
-        cd ..
-        chmod -R u+w $releaseName
-        tar cfJ $out/tarballs/$releaseName.tar.xz $releaseName
-      ''; # */
-    };
-
+  channel = import lib/make-channel.nix { inherit pkgs nixpkgs version versionSuffix; };
 
   manual = buildFromConfig ({ pkgs, ... }: { }) (config: config.system.build.manual.manual);
   manualPDF = (buildFromConfig ({ pkgs, ... }: { }) (config: config.system.build.manual.manualPDF)).x86_64-linux;