Make the manpages build reproducible via datalad.source.epoch (to be used in Debian packaging)

.github/workflows/docbuild.yml

@@ -26,3 +26,11 @@ jobs:
     - name: Build docs
       run: |
         make -C docs html doctest;
+    - name: Test building manpages
+      run: |
+        # with custom date
+        DATALAD_SOURCE_EPOCH=100000000 python setup.py build_manpage
+        grep '\.TH "datalad" "1" "1973' ./build/man/datalad.1
+        # no custom date - should be good for the next 980 years
+        python setup.py build_manpage
+        grep '\.TH "datalad" "1" "2' ./build/man/datalad.1

_datalad_build_support/formatters.py

@@ -7,7 +7,9 @@
 
 import argparse
 import datetime
+import os
 import re
+import time
 from textwrap import wrap
 
 
@@ -25,7 +27,7 @@ def __init__(self,
                  authors=None,
                  version=None
                  ):
-
+        from datalad import cfg
         super(ManPageFormatter, self).__init__(
             prog,
             indent_increment=indent_increment,
@@ -34,7 +36,9 @@ def __init__(self,
 
         self._prog = prog
         self._section = 1
-        self._today = datetime.date.today().strftime('%Y\\-%m\\-%d')
+        self._today = datetime.datetime.utcfromtimestamp(
+            cfg.obtain('datalad.source.epoch')
+        ).strftime('%Y\\-%m\\-%d')
         self._ext_sections = ext_sections
         self._version = version
 

changelog.d/pr-6997.md

@@ -0,0 +1,6 @@
+### Internal
+
+- Introduce datalad.source.epoch configuration to make the build reproducible
+  (on Debian only ATM) by providing date to use in the manpages.
+  [PR #6997](https://github.com/datalad/datalad/pull/6997) (by
+  [@yarikoptic](https://github.com/yarikoptic))

datalad/interface/common_cfg.py

@@ -17,13 +17,15 @@
 from os import environ
 from os.path import expanduser
 from os.path import join as opj
+import time
 
 from platformdirs import AppDirs
 
 from datalad.support.constraints import (
     EnsureBool,
     EnsureChoice,
     EnsureInt,
+    EnsureFloat,
     EnsureListOf,
     EnsureNone,
     EnsureStr,
@@ -709,6 +711,18 @@ def get_default_ssh():
         'type': EnsureChoice('warning', 'error', 'none'),
         'default': 'warning',
 
+    },
+    'datalad.source.epoch': {
+        'ui': ('question', {
+            'title': 'Datetime epoch to use for dates in built materials',
+            'text': "Datetime to use for reproducible builds. Originally introduced "
+                    "for Debian packages to interface SOURCE_DATE_EPOCH described at "
+                    "https://reproducible-builds.org/docs/source-date-epoch/ ."
+                    "By default - current time"
+        }),
+        'type': EnsureFloat(),
+        'default': time.time(),
+
     },
     'datalad.ssh.executable': {
         'ui': ('question', {