Add --setup-requires option to install pip packages before building wheels.

src/pypi2nix/buildout.nix

@@ -1,8 +1,9 @@
-{ buildout_file
+{ buildout_file ? ""
 , project_dir
 , buildout_cache_dir
 , python_version
 , extra_build_inputs ? []
+, setup_requires ? []
 }:
 
 let
@@ -12,23 +13,8 @@ let
     inherit (pkgs) stdenv fetchurl unzip which makeWrapper;
     inherit python;
   };
-in pkgs.stdenv.mkDerivation rec {
-  name = "pypi2nix-buildout";
-
-  buildInputs = with pkgs; [
-    pypi2nix_bootstrap
-    unzip
-    gitAndTools.git
-  ] ++ (pkgs.lib.optional pkgs.stdenv.isLinux pkgs.glibcLocales)
-    ++ (map (name: pkgs.lib.getAttrFromPath
-          (pkgs.lib.splitString "." name) pkgs) extra_build_inputs);
-
-  shellHook = ''
-    export GIT_SSL_CAINFO="${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
-    export SSL_CERT_FILE="${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
-    export PYTHONPATH=${pypi2nix_bootstrap}/base
-    export LANG=en_US.UTF-8
 
+  scriptBuildout = (if buildout_file != "" then ''
     mkdir -p ${buildout_cache_dir}/download ${buildout_cache_dir}/eggs
 
     cat <<EOF > ${project_dir}/buildout.cfg
@@ -52,6 +38,33 @@ in pkgs.stdenv.mkDerivation rec {
     PYTHONPATH=${pypi2nix_bootstrap}/extra:$PYTHONPATH buildout -vvv -c $PWD/pypi2nix.cfg
 
     rm $PWD/pypi2nix.cfg
-  '';
-}
+    '' else "");
+
+  scriptRequires = with builtins; (if (length setup_requires) > 0 then
+    ''
+    mkdir -p ${project_dir}/setup_requires
+    PYTHONPATH=${pypi2nix_bootstrap}/extra:$PYTHONPATH \
+      pip install \
+        ${builtins.concatStringsSep" "(setup_requires)} \
+        --target=${project_dir}/setup_requires
+    '' else "");
 
+in pkgs.stdenv.mkDerivation rec {
+  name = "pypi2nix-buildout";
+
+  buildInputs = with pkgs; [
+    pypi2nix_bootstrap
+    unzip
+    gitAndTools.git
+  ] ++ (pkgs.lib.optional pkgs.stdenv.isLinux pkgs.glibcLocales)
+    ++ (map (name: pkgs.lib.getAttrFromPath
+          (pkgs.lib.splitString "." name) pkgs) extra_build_inputs);
+
+  shellHook = ''
+    export GIT_SSL_CAINFO="${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+    export SSL_CERT_FILE="${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+    export PYTHONPATH=${pypi2nix_bootstrap}/base
+    export LANG=en_US.UTF-8
+
+'' + scriptBuildout + scriptRequires;
+}

src/pypi2nix/cli.py

@@ -76,6 +76,11 @@
               type=str,
               help=u'location/url to editable locations',
               )
+@click.option('-s', '--setup-requires',
+              default=None,
+              help=u'Extra Python dependencies needed before the installation'
+                   u'to build wheels.'
+              )
 def main(version,
          verbose,
          nix_path,
@@ -87,6 +92,7 @@ def main(version,
          requirements,
          buildout,
          editable,
+         setup_requires,
          ):
     """SPECIFICATION should be requirements.txt (output of pip freeze).
     """
@@ -115,6 +121,9 @@ def main(version,
     if extra_build_inputs:
         extra_build_inputs = extra_build_inputs.split(' ')
 
+    if setup_requires:
+        setup_requires = setup_requires.split(' ')
+
     if not cache_dir:
         cache_dir = os.path.join(tmp_dir, 'cache')
 
@@ -200,7 +209,7 @@ def handle_requirements_file(project_dir, requirements_file):
     click.echo('pypi2nix v{} running ...'.format(pypi2nix_version))
     click.echo('')
 
-    if buildout:
+    if buildout or setup_requires:
         click.echo('Stage0: Generating requirements.txt from buildout configuration ...')
         buildout_requirements = pypi2nix.stage0.main(
             verbose=verbose,
@@ -210,8 +219,10 @@ def handle_requirements_file(project_dir, requirements_file):
             extra_build_inputs=extra_build_inputs,
             python_version=pypi2nix.utils.PYTHON_VERSIONS[python_version],
             nix_path=nix_path,
+            setup_requires=setup_requires,
         )
-        requirements_files.append(buildout_requirements)
+        if buildout_requirements:
+            requirements_files.append(buildout_requirements)
 
     if editable:
         editable_file = os.path.join(tmp_dir, 'editable.txt')

src/pypi2nix/pip.nix

@@ -34,7 +34,7 @@ in pkgs.stdenv.mkDerivation rec {
 
     mkdir -p ${project_dir}/wheel ${project_dir}/wheelhouse
 
-    PYTHONPATH=${pypi2nix_bootstrap}/extra:$PYTHONPATH \
+    PYTHONPATH=${pypi2nix_bootstrap}/extra:${project_dir}/setup_requires:$PYTHONPATH \
       pip wheel \
         ${builtins.concatStringsSep" "(map (x: "-r ${x} ") requirements_files)} \
         --wheel-dir ${project_dir}/wheel \

src/pypi2nix/stage0.py

@@ -10,6 +10,7 @@ def main(verbose,
          buildout_cache_dir,
          extra_build_inputs,
          python_version,
+         setup_requires=None,
          nix_path=None,
          ):
     """ Converts buildout.cfg specifiation into requirements.txt file
@@ -23,6 +24,7 @@ def main(verbose,
             buildout_cache_dir=buildout_cache_dir,
             extra_build_inputs=extra_build_inputs,
             python_version=python_version,
+            setup_requires=setup_requires,
         )),
         nix_path=nix_path \
             and ' '.join('-I {}'.format(i) for i in nix_path) \
@@ -36,4 +38,5 @@ def main(verbose,
         raise click.ClickException(
             u'While trying to run the command something went wrong.')
 
-    return os.path.join(project_dir, 'buildout_requirements.txt')
+
+    return buildout_file and os.path.join(project_dir, 'buildout_requirements.txt') or None