Introduce loose deps

Same as in core, introduce DEPS=loose, which allows for loose dependencies.

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <[email protected]> (github: dmp42)

Author: Olivier Gambier

setup.py

@@ -6,6 +6,8 @@
 except ImportError:
     import distutils.core as setuptools
 
+import os
+import re
 import sys
 
 ver = sys.version_info
@@ -17,14 +19,27 @@
 requirements_txt = open('./requirements/main.txt')
 requirements = [line for line in requirements_txt]
 
-if ver[0] == 2:
+if ver < (3, 0):
     # Python 2 requires lzma backport
     requirements.insert(0, 'backports.lzma>=0.0.2')
-    if ver[1] <= 6:
+    if ver < (2, 7):
         # Python 2.6 requires additional libraries
         requirements.insert(0, 'argparse>=1.2.1')
         requirements.insert(0, 'importlib>=1.0.3')
 
+# Using this will relax dependencies to semver major matching
+if 'DEPS' in os.environ and os.environ['DEPS'].lower() == 'loose':
+    loose = []
+    for item in requirements:
+        d = re.match(r'([^=]+)==([0-9]+)[.]([0-9]+)[.]([0-9]+)', item)
+        if d:
+            d = list(d.groups())
+            name = d.pop(0)
+            version = d.pop(0)
+            item = '%s>=%s,<%s' % (name, int(version), int(version) + 1)
+        loose.insert(0, item)
+    requirements = loose
+
 # Require core (the reason this is out of req.txt is to ease tox)
 requirements.insert(0, 'docker-registry-core>=2,<3')