;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2021 Lars-Dominik Braun <lars@6xq.net>
;;; Copyright © 2022 Marius Bakke <marius@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix build pyproject-build-system)
#:use-module ((guix build python-build-system) #:prefix python:)
#:use-module (guix build utils)
#:use-module (guix build json)
#:use-module (ice-9 match)
#:use-module (ice-9 ftw)
#:use-module (ice-9 format)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 regex)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:export (%standard-phases
add-installed-pythonpath
site-packages
python-version
pyproject-build))
;;; Commentary:
;;;
;;; PEP 517-compatible build system for Python packages.
;;;
;;; PEP 517 mandates the use of a TOML file called pyproject.toml at the
;;; project root, describing build and runtime dependencies, as well as the
;;; build system, which can be different from setuptools. This module uses
;;; that file to extract the build system used and call its wheel-building
;;; entry point build_wheel (see 'build). setuptools’ wheel builder is
;;; used as a fallback if either no pyproject.toml exists or it does not
;;; declare a build-system. It supports config_settings through the
;;; standard #:configure-flags argument.
;;;
;;; This wheel, which is just a ZIP file with a file structure defined
;;; by PEP 427 (https://www.python.org/dev/peps/pep-0427/), is then unpacked
;;; and its contents are moved to the appropriate locations in 'install.
;;;
;;; Then entry points, as defined by the PyPa Entry Point Specification
;;; (https://packaging.python.org/specifications/entry-points/) are read
;;; from a file called entry_points.txt in the package’s site-packages
;;; subdirectory and scripts are written to bin/. These are not part of a
;;; wheel and expected to be created by the installing utility.
;;; TODO: Add support for PEP-621 entry points.
;;;
;;; Caveats:
;;; - There is no support for in-tree build backends.
;;;
;;; Code:
;;;
;; Re-export these variables from python-build-system as many packages
;; rely on these.
(define python-version python:python-version)
(define site-packages python:site-packages)
(define add-installed-pythonpath python:add-installed-pythonpath)
;; Base error type.
(define-condition-type &python-build-error &error python-build-error?)
;; Raised when 'check cannot find a valid test system in the inputs.
(define-condition-type &test-system-not-found &python-build-error
test-system-not-found?)
;; Raised when multiple wheels are created by 'build.
(define-condition-type &cannot-extract-multiple-wheels &python-build-error
cannot-extract-multiple-wheels?)
;; Raised, when no wheel has been built by the build system.
(define-condition-type &no-wheels-built &python-build-error no-wheels-built?)
(define* (build #:key outputs build-backend configure-flags #:allow-other-keys)
"Build a given Python package."
(define (pyproject.toml->build-backend file)
"Look up the build backend in a pyproject.toml file."
(call-with-input-file file
(lambda (in)
(let loop
((line (read-line in 'concat)))
(if (eof-object? line) #f
(let ((m (string-match "build-backend = [\"'](.+)[\"']" line)))
(if m
(match:substring m 1)
(loop (read-line in 'concat)))))))))
(let* ((wheel-output (assoc-ref outputs "wheel"))
(wheel-dir (if wheel-output wheel-output "dist"))
;; There is no easy way to get data from Guile into Python via
;; s-expressions, but we have JSON serialization already, which Python
;; also supports out-of-the-box.
(config-settings (call-with-output-string
(cut write-json configure-flags <>)))
;; python-setuptools’ default backend supports setup.py *and*
;; pyproject.toml. Allow overriding this automatic detection via
;; build-backend.
(auto-build-backend (if (file-exists? "pyproject.toml")
(pyproject.toml->build-backend
"pyproject.toml")
#f))
;; Use build system detection here and not in importer, because a) we
;; have alot of legacy packages and b) the importer cannot update arbitrary
;; fields in case a package switches its build system.
(use-build-backend (or build-backend
auto-build-backend
"setuptools.build_meta")))
(format #t
"Using '~a' to build wheels, auto-detected '~a', override '~a'.~%"
use-build-backend auto-build-backend build-backend)
(mkdir-p wheel-dir)
;; Call the PEP 517 build function, which drops a .whl into wheel-dir.
(invoke "python" "-c"
"import sys, importlib, json
config_settings = json.loads (sys.argv[3])
builder = importlib.import_module(sys.argv[1])
builder.build_wheel(sys.argv[2], config_settings=config_settings)"
use-build-backend
wheel-dir
config-settings)))
(define* (check #:key tests? test-backend test-flags #:allow-other-keys)
"Run the test suite of a given Python package."
(if tests?
;; Unfortunately with PEP 517 there is no common method to specify test
;; systems. Guess test system based on inputs instead.
(let* ((pytest (which "pytest"))
(nosetests (which "nosetests"))
(nose2 (which "nose2"))
(have-setup-py (file-exists? "setup.py"))
(use-test-backend
(or test-backend
;; Prefer pytest
(if pytest 'pytest #f)
(if nosetests 'nose #f)
(if nose2 'nose2 #f)
;; But fall back to setup.py, which should work for most
;; packages. XXX: would be nice not to depend on setup.py here?
;; fails more often than not to find any tests at all. Maybe
;; we can run `python -m unittest`?
(if have-setup-py 'setup.py #f))))
(format #t "Using ~a~%" use-test-backend)
(match use-test-backend
('pytest
(apply invoke pytest "-vv" test-flags))
('nose
(apply invoke nosetests "-v" test-flags))
('nose2
(apply invoke nose2 "-v" "--pretty-assert" test-flags))
('setup.py
(apply invoke "python" "setup.py"
(if (null? test-flags)
'("test" "-v")
test-flags)))
;; The developer should explicitly disable tests in this case.
(else (raise (condition (&test-system-not-found))))))
(format #t "test suite not run~%")))
(define* (install #:key inputs outputs #:allow-other-keys)
"Install a wheel file according to PEP 427"
;; See https://www.python.org/dev/peps/pep-0427/#installing-a-wheel-distribution-1-0-py32-none-any-whl
(let ((site-dir (site-packages inputs outputs))
(python (assoc-ref inputs "python"))
(out (assoc-ref outputs "out")))
(define (extract file)
"Extract wheel (ZIP file) into site-packages directory"
;; Use Python’s zipfile to avoid extra dependency
(invoke "python" "-m" "zipfile" "-e" file site-dir))
(define python-hashbang
(string-append "#!" python "/bin/python"))
(define* (merge-directories source destination
#:optional (post-move #f))
"Move all files in SOURCE into DESTINATION, merging the two directories."
(format #t "Merging directory ~a into ~a~%" source destination)
(for-each (lambda (file)
(format #t "~a/~a -> ~a/~a~%"
source file destination file)
(mkdir-p destination)
(rename-file (string-append source "/" file)
(string-append destination "/" file))
(when post-move
(post-move file)))
(scandir source
(negate (cut member <> '("." "..")))))
(rmdir source))
(define (expand-data-directory directory)
"Move files from all .data subdirectories to their respective\ndestinations."
;; Python’s distutils.command.install defines this mapping from source to
;; destination mapping.
(let ((source (string-append directory "/scripts"))
(destination (string-append out "/bin")))
(when (file-exists? source)
(merge-directories source destination
(lambda (f)
(let ((dest-path (string-append destination
"/" f)))
(chmod dest-path #o755)
;; PEP 427 recommends that installers rewrite
;; this odd shebang.
(substitute* dest-path
(("#!python")
python-hashbang)))))))
;; Data can be contained in arbitrary directory structures. Most
;; commonly it is used for share/.
(let ((source (string-append directory "/data"))
(destination out))
(when (file-exists? source)
(merge-directories source destination)))
(let* ((distribution (car (string-split (basename directory) #\-)))
(source (string-append directory "/headers"))
(destination (string-append out "/include/python"
(python-version python)
"/" distribution)))
(when (file-exists? source)
(merge-directories source destination))))
(define (list-directories base predicate)
;; Cannot use find-files here, because it’s recursive.
(scandir base
(lambda (name)
(let ((stat (lstat (string-append base "/" name))))
(and (not (member name '("." "..")))
(eq? (stat:type stat) 'directory)
(predicate name stat))))))
(let* ((wheel-output (assoc-ref outputs "wheel"))
(wheel-dir (if wheel-output wheel-output "dist"))
(wheels (map (cut string-append wheel-dir "/" <>)
(scandir wheel-dir
(cut string-suffix? ".whl" <>)))))
(cond
((> (length wheels) 1)
;; This code does not support multiple wheels yet, because their
;; outputs would have to be merged properly.
(raise (condition (&cannot-extract-multiple-wheels))))
((= (length wheels) 0)
(raise (condition (&no-wheels-built)))))
(for-each extract wheels))
(let ((datadirs (map (cut string-append site-dir "/" <>)
(list-directories site-dir
(file-name-predicate "\\.data$")))))
(for-each (lambda (directory)
(expand-data-directory directory)
(rmdir directory)) datadirs))))
(define* (compile-bytecode #:key inputs outputs #:allow-other-keys)
"Compile installed byte-code in site-packages."
(let* ((site-dir (site-packages inputs outputs))
(python (assoc-ref inputs "python"))
(major-minor (map string->number
(take (string-split (python-version python) #\.) 2)))
(<3.7? (match major-minor
((major minor)
(or (< major 3)
(and (= major 3)
(< minor 7)))))))
(if <3.7?
;; These versions don’t have the hash invalidation modes and do
;; not produce reproducible bytecode files.
(format #t "Skipping bytecode compilation for Python version ~a < 3.7~%"
(python-version python))
(invoke "python" "-m" "compileall"
"--invalidation-mode=unchecked-hash" site-dir))))
(define* (create-entrypoints #:key inputs outputs #:allow-other-keys)
"Implement Entry Points Specification
(https://packaging.python.org/specifications/entry-points/) by PyPa,
which creates runnable scripts in bin/ from entry point specification
file entry_points.txt. This is necessary, because wheels do not contain
these binaries and installers are expected to create them."
(define (entry-points.txt->entry-points file)
"Specialized parser for Python configfile-like files, in particular
entry_points.txt. Returns a list of console_script and gui_scripts
entry points."
(call-with-input-file file
(lambda (in)
(let loop ((line (read-line in))
(inside #f)
(result '()))
(if (eof-object? line)
result
(let* ((group-match (string-match "^\\[(.+)\\]$" line))
(group-name (if group-match
(match:substring group-match 1)
#f))
(next-inside (if (not group-name)
inside
(or (string=? group-name
"console_scripts")
(string=? group-name "gui_scripts"))))
(item-match (string-match
"^([^ =]+)\\s*=\\s*([^:]+):(.+)$" line)))
(if (and inside item-match)
(loop (read-line in)
next-inside
(cons (list (match:substring item-match 1)
(match:substring item-match 2)
(match:substring item-match 3))
result))
(loop (read-line in) next-inside result))))))))
(define (create-script path name module function)
"Create a Python script from an entry point’s NAME, MODULE and FUNCTION
and return write it to PATH/NAME."
(let ((interpreter (which "python"))
(file-path (string-append path "/" name)))
(format #t "Creating entry point for '~a.~a' at '~a'.~%"
module function file-path)
(call-with-output-file file-path
(lambda (port)
;; Technically the script could also include search-paths,
;; but having a generic 'wrap phases also handles manually
;; written entry point scripts.
(format port "#!~a
# Auto-generated entry point script.
import sys
import ~a as mod
sys.exit (mod.~a ())~%" interpreter module function)))
(chmod file-path #o755)))
(let* ((site-dir (site-packages inputs outputs))
(out (assoc-ref outputs "out"))
(bin-dir (string-append out "/bin"))
(entry-point-files (find-files site-dir "^entry_points.txt$")))
(mkdir-p bin-dir)
(for-each (lambda (f)
(for-each (lambda (ep)
(apply create-script
(cons bin-dir ep)))
(entry-points.txt->entry-points f)))
entry-point-files)))
(define* (set-SOURCE-DATE-EPOCH* #:rest _)
"Set the 'SOURCE_DATE_EPOCH' environment variable. This is used by tools
that incorporate timestamps as a way to tell them to use a fixed timestamp.
See https://reproducible-builds.org/specs/source-date-epoch/."
;; Use a post-1980 timestamp because the Zip format used in wheels do
;; not support timestamps before 1980.
(setenv "SOURCE_DATE_EPOCH" "315619200"))
(define %standard-phases
;; The build phase only builds C extensions and copies the Python sources,
;; while the install phase copies then byte-compiles the sources to the
;; prefix directory. The check phase is moved after the installation phase
;; to ease testing the built package.
(modify-phases python:%standard-phases
(replace 'set-SOURCE-DATE-EPOCH set-SOURCE-DATE-EPOCH*)
(replace 'build build)
(replace 'install install)
(delete 'check)
;; Must be before tests, so they can use installed packages’ entry points.
(add-before 'wrap 'create-entrypoints create-entrypoints)
(add-after 'wrap 'check check)
(add-before 'check 'compile-bytecode compile-bytecode)))
(define* (pyproject-build #:key inputs (phases %standard-phases)
#:allow-other-keys #:rest args)
"Build the given Python package, applying all of PHASES in order."
(apply python:python-build #:inputs inputs #:phases phases args))
;;; pyproject-build-system.scm ends here