Merge pull request #21 from joerick/environment

CIBW_ENVIRONMENT
Fixes #16

cibuildwheel/__main__.py

@@ -3,6 +3,7 @@ import argparse, os, subprocess, sys, textwrap
 
 import cibuildwheel
 import cibuildwheel.linux, cibuildwheel.windows, cibuildwheel.macos
+from cibuildwheel.environment import parse_environment, EnvironmentParseError
 from cibuildwheel.util import BuildSkipper
 
 def get_option_from_environment(option_name, platform=None):
@@ -72,6 +73,15 @@ def main():
     project_dir = args.project_dir
     before_build = get_option_from_environment('CIBW_BEFORE_BUILD', platform=platform)
     skip_config = os.environ.get('CIBW_SKIP', '')
+    environment_config = get_option_from_environment('CIBW_ENVIRONMENT', platform=platform) or ''
+
+    try:
+        environment = parse_environment(environment_config)
+    except (EnvironmentParseError, ValueError) as e:
+        print('cibuildwheel: Malformed environment option "%s"' % environment_config, file=sys.stderr)
+        import traceback
+        traceback.print_exc(None, sys.stderr)
+        exit(2)
 
     skip = BuildSkipper(skip_config)
 
@@ -103,6 +113,7 @@ def main():
         test_requires=test_requires,
         before_build=before_build,
         skip=skip,
+        environment=environment,
     )
 
     print_preamble(platform, build_options)