Merge lp:~blr/charm-helpers/pip-constraints into lp:charm-helpers

[Kit Randel]

Add pip constraints support.

Provides support for pip constraints files in contrib.python.packages.pip_install_requirements (http://pip.readthedocs.org/en/stable/user_guide/#constraints-files).

[lp:~blr/charm-helpers/pip-constraints]

477. By Kit Randel on 2015-11-03

Tidy up docstring.

[Stuart Bishop (stub)]

This all looks good.

review: Approve

=== modified file 'charmhelpers/contrib/python/packages.py'
--- charmhelpers/contrib/python/packages.py	2015-06-24 18:47:47 +0000
+++ charmhelpers/contrib/python/packages.py	2015-11-03 19:41:19 +0000
@@ -42,8 +42,12 @@
             yield "--{0}={1}".format(key, value)
 
 
-def pip_install_requirements(requirements, **options):
-    """Install a requirements file """
+def pip_install_requirements(requirements, constraints=None, **options):
+    """Install a requirements file.
+
+    :param constraints: Path to pip constraints file.
+    http://pip.readthedocs.org/en/stable/user_guide/#constraints-files
+    """
     command = ["install"]
 
     available_options = ('proxy', 'src', 'log', )
@@ -51,8 +55,13 @@
         command.append(option)
 
     command.append("-r {0}".format(requirements))
-    log("Installing from file: {} with options: {}".format(requirements,
-                                                           command))
+    if constraints:
+        command.append("-c {0}".format(constraints))
+        log("Installing from file: {} with constraints {} "
+            "and options: {}".format(requirements, constraints, command))
+    else:
+        log("Installing from file: {} with options: {}".format(requirements,
+                                                               command))
     pip_execute(command)
 
 
 
=== modified file 'tests/contrib/python/test_packages.py'
--- tests/contrib/python/test_packages.py	2015-05-06 15:51:25 +0000
+++ tests/contrib/python/test_packages.py	2015-11-03 19:41:19 +0000
@@ -44,6 +44,12 @@
                                              "-r test_requirements.txt"])
 
         packages.pip_install_requirements("test_requirements.txt",
+                                          "test_constraints.txt")
+        self.pip_execute.assert_called_with(["install",
+                                             "-r test_requirements.txt",
+                                             "-c test_constraints.txt"])
+
+        packages.pip_install_requirements("test_requirements.txt",
                                           proxy="proxy_addr:8080")
 
         self.pip_execute.assert_called_with(["install",