add environment evaluation

cibuildwheel/linux.py

@@ -135,7 +135,21 @@ def build(options: BuildOptions) -> None:
 
             if options.before_all:
                 before_all_prepared = prepare_command(options.before_all, project='/project', package=options.package_dir)
-                call(['docker', 'exec', '-i', container_name] + shell_cmd, universal_newlines=True, input=before_all_prepared)
+                task = """
+                PS4='    + '
+
+                set -o errexit
+                set -o xtrace
+
+                {environment_exports}
+
+                {before_all_prepared}
+
+                """.format(
+                    environment_exports='\n'.join(options.environment.as_shell_commands()),
+                    before_all_prepared=before_all_prepared
+                )
+                call(['docker', 'exec', '-i', container_name] + shell_cmd, universal_newlines=True, input=task)
 
             for config in platform_configs:
                 if options.dependency_constraints:

cibuildwheel/macos.py

@@ -177,8 +177,9 @@ def build(options: BuildOptions) -> None:
     repaired_wheel_dir = temp_dir / 'repaired_wheel'
 
     if options.before_all:
+        env = options.environment.as_dictionary(prev_environment=os.environ)
         before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
-        call([before_all_prepared], shell=True)
+        call([before_all_prepared], shell=True, env=env)
 
     python_configurations = get_python_configurations(options.build_selector)
 

cibuildwheel/windows.py

@@ -163,8 +163,9 @@ def build(options: BuildOptions) -> None:
     download('https://dist.nuget.org/win-x86-commandline/latest/nuget.exe', nuget)
 
     if options.before_all:
+        env = options.environment.as_dictionary(prev_environment=os.environ)
         before_all_prepared = prepare_command(options.before_all, project='.', package=options.package_dir)
-        shell([before_all_prepared])
+        shell([before_all_prepared], env=env)
 
     python_configurations = get_python_configurations(options.build_selector)
     for config in python_configurations:

docs/options.md

@@ -198,6 +198,8 @@ This option is added mainly for linux build, because linux wheels are build in i
 
 The placeholder `{package}` can be used here; it will be replaced by the path to the package being built by `cibuildwheel`.
 
+For windows and macos `CIBW_BEFORE_ALL` python interpreter is same as `cibuildwheel` is run. For linux it is default interpreter for docker image. 
+
 Platform-specific variants also available:<br/>
  `CIBW_BEFORE_ALL_MACOS` | `CIBW_BEFORE_ALL_WINDOWS` | `CIBW_BEFORE_ALL_LINUX`
 

test/14_before_all/cibuildwheel_test.py

@@ -13,7 +13,8 @@ def test():
     actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
         # write python version information to a temporary file, this is
         # checked in setup.py
-        'CIBW_BEFORE_ALL': '''python -c "open('{project}/text_info.txt', 'w').write('sample text')"''',
+        'CIBW_BEFORE_ALL': '''python -c "import os;open('{project}/text_info.txt', 'w').write('sample text '+os.environ.get('TEST_VAL', ''))"''',
+        'CIBW_ENVIRONMENT': "TEST_VAL='123'"
     })
 
     # also check that we got the right wheels

test/14_before_all/setup.py

@@ -9,7 +9,7 @@ with open("text_info.txt") as f:
     stored_text = f.read()
 
 print("## stored text: " + stored_text)
-assert stored_text == "sample text"
+assert stored_text == "sample text 123"
 
 
 setup(