Introduce upper constraints

This is a global setting that will apply across every project, a
constraint on the versions of things that can be installed via pip.

This is a first pass, adding basic functionality, by allowing a list
of constraint URLs to be provided. Future iterations of this feature may be
tied to a "superrepo" that contains all the projects _and_ the
constraints for those projects all in one place.

Change-Id: Ib5c2dd441b9294b775e755e595486a671d8de57f

giftwrap/builders/__init__.py

@@ -18,6 +18,8 @@ import logging
 import os
 import threading
 
+import requests
+
 from giftwrap.gerrit import GerritReview
 from stevedore.driver import DriverManager
 from stevedore.extension import ExtensionManager
@@ -36,6 +38,7 @@ class Builder(object):
         self._temp_src_dir = None
         self._spec = spec
         self._thread_exit = []
+        self._constraints = []
 
     @staticmethod
     def builder_names(ext_mgr=None):
@@ -55,6 +58,30 @@ class Builder(object):
                         "Error was: %s", e)
             return []
 
+    def _get_constraints(self):
+        cfiles = []
+        try:
+            for count, constraint_url in \
+                enumerate(self._spec.settings.constraints, 1):
+                response = requests.get(constraint_url)
+
+                # Raise an error if we got a bad URL
+                response.raise_for_status()
+
+                constraints = response.text.encode('utf-8')
+                cfilepath = os.path.join(self._temp_dir,
+                                         'constraints-%s.txt' % count)
+
+                with open(cfilepath, 'w') as cfile:
+                    cfile.write(constraints)
+
+                cfiles.append(cfilepath)
+
+            return cfiles
+
+        except Exception as e:
+            raise Exception("Unable to construct constraints. Error: %s" % e)
+
     def _build_project(self, project):
         try:
             self._prepare_project_build(project)
@@ -105,6 +132,9 @@ class Builder(object):
         self._temp_src_dir = os.path.join(self._temp_dir, 'src')
         LOG.debug("Temporary working directory: %s", self._temp_dir)
 
+        # get constraints paths
+        self._constraints = self._get_constraints()
+
         threads = []
         for project in spec.projects:
             if spec.settings.parallel_build:

giftwrap/builders/docker_builder.py

@@ -84,8 +84,11 @@ class DockerBuilder(Builder):
 
     def _install_pip_dependencies(self, venv_path, dependencies):
         pip_path = self._get_venv_pip_path(venv_path)
+        install = "install"
+        for constraint in self._constraints:
+            install = "%s -c %s" % (install, constraint)
         for dependency in dependencies:
-            self._execute("%s install %s" % (pip_path, dependency))
+            self._execute("%s %s %s" % (pip_path, install, dependency))
 
     def _copy_sample_config(self, src_clone_dir, project):
         src_config = os.path.join(src_clone_dir, 'etc')
@@ -96,7 +99,10 @@ class DockerBuilder(Builder):
 
     def _install_project(self, venv_path, src_clone_dir):
         pip_path = self._get_venv_pip_path(venv_path)
-        self._execute("%s install %s" % (pip_path, src_clone_dir))
+        install = "install"
+        for constraint in self._constraints:
+            install = "%s -c %s" % (install, constraint)
+        self._execute("%s %s %s" % (pip_path, install, src_clone_dir))
 
     def _finalize_project_build(self, project):
         self._commands.append("rm -rf %s" % self._temp_dir)

giftwrap/builders/package_builder.py

@@ -70,8 +70,11 @@ class PackageBuilder(Builder):
 
     def _install_pip_dependencies(self, venv_path, dependencies):
         pip_path = self._get_venv_pip_path(venv_path)
+        install = "install"
+        for constraint in self._constraints:
+            install = "%s -c %s" % (install, constraint)
         for dependency in dependencies:
-            self._execute("%s install %s" % (pip_path, dependency))
+            self._execute("%s %s %s" % (pip_path, install, dependency))
 
     def _copy_sample_config(self, src_clone_dir, project):
         src_config = os.path.join(src_clone_dir, 'etc')
@@ -87,7 +90,10 @@ class PackageBuilder(Builder):
 
     def _install_project(self, venv_path, src_clone_dir):
         pip_path = self._get_venv_pip_path(venv_path)
-        self._execute("%s install %s" % (pip_path, src_clone_dir))
+        install = "install"
+        for constraint in self._constraints:
+            install = "%s -c %s" % (install, constraint)
+        self._execute("%s %s %s" % (pip_path, install, src_clone_dir))
 
     def _finalize_project_build(self, project):
         # build the package

giftwrap/settings.py

@@ -31,9 +31,11 @@ class Settings(object):
                  package_name_format=None, version=None,
                  base_path=None, install_path=None, gerrit_dependencies=True,
                  force_overwrite=False, output_dir=None, include_config=True,
-                 parallel_build=True):
+                 parallel_build=True, constraints=[]):
         if not version:
             raise Exception("'version' is a required settings")
+        if not isinstance(constraints, list):
+            raise Exception("'constraints' is required to be a list")
         self.build_type = build_type
         self._package_name_format = package_name_format
         self.version = version
@@ -44,6 +46,7 @@ class Settings(object):
         self._output_dir = output_dir
         self.include_config = include_config
         self.parallel_build = parallel_build
+        self.constraints = constraints
 
     @property
     def package_name_format(self):

giftwrap/tests/test_settings.py

@@ -22,7 +22,8 @@ from giftwrap import settings
 SAMPLE_SETTINGS = {
     'package_name_format': 'my-package-name',
     'version': '1.2',
-    'base_path': '/basepath'
+    'base_path': '/basepath',
+    'constraints': ['http://example.txt'],
 }
 
 
@@ -35,6 +36,7 @@ class TestSettings(unittest.TestCase):
         self.assertEquals('my-package-name', s.package_name_format)
         self.assertEquals('1.2', s.version)
         self.assertEquals('/basepath', s.base_path)
+        self.assertEquals('http://example.txt', s.constraints[0])
 
     def test_factory_has_default_base_path(self):
         settings_dict = {'version': 'version'}
@@ -48,3 +50,10 @@ class TestSettings(unittest.TestCase):
 
         with self.assertRaises(Exception):
             settings.Settings.factory(settings_dict)
+
+    def test_factory_raises_when_constraints_invalid(self):
+        settings_dict = SAMPLE_SETTINGS
+        settings_dict['constraints'] = 'notalist'
+
+        with self.assertRaises(Exception):
+            settings.Settings.factory(settings_dict)