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Diffstat (limited to 'tools/nixery/build-image/load-pkgs.nix')
| -rw-r--r-- | tools/nixery/build-image/load-pkgs.nix | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/tools/nixery/build-image/load-pkgs.nix b/tools/nixery/build-image/load-pkgs.nix new file mode 100644 index 000000000000..3e8b450c45d2 --- /dev/null +++ b/tools/nixery/build-image/load-pkgs.nix @@ -0,0 +1,73 @@ +# 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. + +# Load a Nix package set from a source specified in one of the following +# formats: +# +# 1. nixpkgs!$channel (e.g. nixpkgs!nixos-19.03) +# 2. git!$repo!$rev (e.g. git!git@github.com:NixOS/nixpkgs.git!master) +# 3. path!$path (e.g. path!/var/local/nixpkgs) +# +# '!' was chosen as the separator because `builtins.split` does not +# support regex escapes and there are few other candidates. It +# doesn't matter much because this is invoked by the server. +{ pkgSource, args ? { } }: + +with builtins; +let + # If a nixpkgs channel is requested, it is retrieved from Github (as + # a tarball) and imported. + fetchImportChannel = channel: + let + url = + "https://github.com/NixOS/nixpkgs-channels/archive/${channel}.tar.gz"; + in import (fetchTarball url) args; + + # If a git repository is requested, it is retrieved via + # builtins.fetchGit which defaults to the git configuration of the + # outside environment. This means that user-configured SSH + # credentials etc. are going to work as expected. + fetchImportGit = url: rev: + let + # builtins.fetchGit needs to know whether 'rev' is a reference + # (e.g. a branch/tag) or a revision (i.e. a commit hash) + # + # Since this data is being extrapolated from the supplied image + # tag, we have to guess if we want to avoid specifying a format. + # + # There are some additional caveats around whether the default + # branch contains the specified revision, which need to be + # explained to users. + spec = if (stringLength rev) == 40 then { + inherit url rev; + } else { + inherit url; + ref = rev; + }; + in import (fetchGit spec) args; + + # No special handling is used for paths, so users are expected to pass one + # that will work natively with Nix. + importPath = path: import (toPath path) args; + + source = split "!" pkgSource; + sourceType = elemAt source 0; +in if sourceType == "nixpkgs" then + fetchImportChannel (elemAt source 2) +else if sourceType == "git" then + fetchImportGit (elemAt source 2) (elemAt source 4) +else if sourceType == "path" then + importPath (elemAt source 2) +else + throw ("Invalid package set source specification: ${pkgSource}") |