Build requirements from setup.py

README.md

@@ -23,21 +23,46 @@ $ pip install pip-tools
 Example usage for `pip-compile`
 ===============================
 
-Suppose you have a Flask project, and want to pin it for production.  Write the
-following line to a file:
+Requirements from setup.py
+--------------------------
+
+Suppose you have a Flask project, and want to pin it for production.  If you have a `setup.py` with
+`install_requires=['Flask']`, then run `pip-compile` without any arguments:
+```console
+$ pip-compile
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --output-file requirements.txt setup.py
+#
+flask==0.10.1
+itsdangerous==0.24        # via flask
+jinja2==2.7.3             # via flask
+markupsafe==0.23          # via jinja2
+werkzeug==0.10.4          # via flask
+```
+
+`pip-compile` will produce your `requirements.txt`, with all the Flask dependencies
+(and all underlying dependencies) pinned.  You should put your requirements file under version control.
+
+Without setup.py
+----------------
+
+If you don't use `setup.py` ([it's easy to write one][1]), you can instead write the following line to a file:
 
     # requirements.in
     Flask
 
-Now, run `pip-compile requirements.in`:
+This time, run `pip-compile requirements.in`:
 
 ```console
 $ pip-compile requirements.in
 #
 # This file is autogenerated by pip-compile
-# Make changes in requirements.in, then run this to update:
+# To update, run:
 #
-#    pip-compile requirements.in
+#    pip-compile --output-file requirements.txt requirements.in
 #
 flask==0.10.1
 itsdangerous==0.24        # via flask
@@ -47,8 +72,12 @@ werkzeug==0.10.4          # via flask
 ```
 
 And it will produce your `requirements.txt`, with all the Flask dependencies
-(and all underlying dependencies) pinned.  Put this file under version control
-as well.
+(and all underlying dependencies) pinned.  Don't forget to put this file under version control as well.
+
+[1]: https://packaging.python.org/distributing/#configuring-your-project
+
+Updating requirements
+---------------------
 
 To update all packages, periodically re-run `pip-compile --upgrade`.
 

piptools/scripts/compile.py

@@ -67,10 +67,15 @@ def cli(verbose, dry_run, pre, rebuild, find_links, index_url, extra_index_url,
     log.verbose = verbose
 
     if len(src_files) == 0:
-        if not os.path.exists(DEFAULT_REQUIREMENTS_FILE):
+        if os.path.exists(DEFAULT_REQUIREMENTS_FILE):
+            src_files = (DEFAULT_REQUIREMENTS_FILE,)
+        elif os.path.exists('setup.py'):
+            src_files = ('setup.py',)
+            if not output_file:
+                output_file = 'requirements.txt'
+        else:
             raise click.BadParameter(("If you do not specify an input file, "
-                                      "the default is {}").format(DEFAULT_REQUIREMENTS_FILE))
-        src_files = (DEFAULT_REQUIREMENTS_FILE,)
+                                      "the default is {} or setup.py").format(DEFAULT_REQUIREMENTS_FILE))
 
     if len(src_files) == 1 and src_files[0] == '-':
         if not output_file:
@@ -166,12 +171,19 @@ def cli(verbose, dry_run, pre, rebuild, find_links, index_url, extra_index_url,
 
     constraints = []
     for src_file in src_files:
-        if src_file == '-':
+        is_setup_file = os.path.basename(src_file) == 'setup.py'
+        if is_setup_file or src_file == '-':
             # pip requires filenames and not files. Since we want to support
             # piping from stdin, we need to briefly save the input from stdin
-            # to a temporary file and have pip read that.
+            # to a temporary file and have pip read that.  also used for
+            # reading requirements from install_requires in setup.py.
             with tempfile.NamedTemporaryFile(mode='wt') as tmpfile:
-                tmpfile.write(sys.stdin.read())
+                if is_setup_file:
+                    from distutils.core import run_setup
+                    dist = run_setup(src_file)
+                    tmpfile.write('\n'.join(dist.install_requires))
+                else:
+                    tmpfile.write(sys.stdin.read())
                 tmpfile.flush()
                 constraints.extend(parse_requirements(
                     tmpfile.name, finder=repository.finder, session=repository.session, options=pip_options))