Add a Linux implementation of environment

cibuildwheel/linux.py

@@ -9,7 +9,7 @@ except ImportError:
     from pipes import quote as shlex_quote
 
 
-def build(project_dir, package_name, output_dir, test_command, test_requires, before_build, skip):
+def build(project_dir, package_name, output_dir, test_command, test_requires, before_build, skip, environment):
     try:
         subprocess.check_call(['docker', '--version'])
     except:
@@ -52,6 +52,8 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             set -o xtrace
             cd /project
 
+            {environment_exports}
+
             for PYBIN in {pybin_paths}; do
                 # Setup
                 rm -rf /tmp/built_wheel
@@ -106,6 +108,9 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             before_build=shlex_quote(
                 prepare_command(before_build, python='python', pip='pip') if before_build else ''
             ),
+            environment_exports=' '.join(
+                ('export %s=%s\n' % (key, shlex_quote(value)) for key, value in environment.items())
+            ),
         )
 
         docker_process = subprocess.Popen([