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authorVincent Ambo <tazjin@google.com>2019-09-30T13·19+0100
committerVincent Ambo <github@tazj.in>2019-10-03T12·21+0100
commit6262dec8aacf25ae6004de739353089cd635cea5 (patch)
tree98da57af6cba292c63901510ed9b49bc9dcf63ca /tools/nixery/build-image
parent2c8ef634f67f91c8efc1cf6a58a271f4c44544dd (diff)
feat(nix): Add derivation to create layer tars from a store path set
This introduces a new Nix derivation that, given an attribute set of
layer hashes mapped to store paths, will create a layer tarball for
each of the store paths.

This is going to be used by the builder to create layers that are not
present in the cache.

Relates to #50.
Diffstat (limited to 'tools/nixery/build-image')
-rw-r--r--tools/nixery/build-image/build-layers.nix47
-rw-r--r--tools/nixery/build-image/default.nix24
2 files changed, 64 insertions, 7 deletions
diff --git a/tools/nixery/build-image/build-layers.nix b/tools/nixery/build-image/build-layers.nix
new file mode 100644
index 000000000000..8a8bfbe9edf1
--- /dev/null
+++ b/tools/nixery/build-image/build-layers.nix
@@ -0,0 +1,47 @@
+# Copyright 2019 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+{
+  # Description of the package set to be used (will be loaded by load-pkgs.nix)
+  srcType ? "nixpkgs",
+  srcArgs ? "nixos-19.03",
+  importArgs ? { },
+  # Path to load-pkgs.nix
+  loadPkgs ? ./load-pkgs.nix,
+  # Layers to assemble into tarballs
+  layers ? "{}"
+}:
+
+let
+  inherit (builtins) fromJSON mapAttrs toJSON;
+  inherit (pkgs) lib runCommand;
+
+  pkgs = import loadPkgs { inherit srcType srcArgs importArgs; };
+
+  # Given a list of store paths, create an image layer tarball with
+  # their contents.
+  pathsToLayer = paths: runCommand "layer.tar" {
+  } ''
+    tar --no-recursion -Prf "$out" \
+        --mtime="@$SOURCE_DATE_EPOCH" \
+        --owner=0 --group=0 /nix /nix/store
+
+    tar -Prpf "$out" --hard-dereference --sort=name \
+        --mtime="@$SOURCE_DATE_EPOCH" \
+        --owner=0 --group=0 ${lib.concatStringsSep " " paths}
+  '';
+
+
+  layerTarballs = mapAttrs (_: pathsToLayer ) (fromJSON layers);
+in writeText "layer-tarballs.json" (toJSON layerTarballs)
diff --git a/tools/nixery/build-image/default.nix b/tools/nixery/build-image/default.nix
index a61ac06bdd92..0800eb95987f 100644
--- a/tools/nixery/build-image/default.nix
+++ b/tools/nixery/build-image/default.nix
@@ -20,10 +20,20 @@
 
 { pkgs ? import <nixpkgs> {} }:
 
-pkgs.writeShellScriptBin "nixery-build-image" ''
-  exec ${pkgs.nix}/bin/nix-build \
-    --show-trace \
-    --no-out-link "$@" \
-    --argstr loadPkgs ${./load-pkgs.nix} \
-    ${./build-image.nix}
-''
+{
+  build-image = pkgs.writeShellScriptBin "nixery-build-image" ''
+    exec ${pkgs.nix}/bin/nix-build \
+      --show-trace \
+      --no-out-link "$@" \
+      --argstr loadPkgs ${./load-pkgs.nix} \
+      ${./build-image.nix}
+  '';
+
+  build-layers = pkgs.writeShellScriptBin "nixery-build-layers" ''
+    exec ${pkgs.nix}/bin/nix-build \
+      --show-trace \
+      --no-out-link "$@" \
+      --argstr loadPkgs ${./load-pkgs.nix} \
+      ${./build-layers.nix}
+  '';
+}