Remove extraneous dependency

The rstr library relies on the normal random.SystemRandom() and does not
perform additional functionalites that would require a whole dependency
to be added to pegleg. This patch set places in the logic into pegleg's
crypto generation rather than using the whole rstr library.

Change-Id: I20c0ceae8ac7d11468f325cd6a4cc035fc176b14
Signed-off-by: Tin Lam <tin@irrational.io>

pegleg/engine/util/cryptostring.py

@@ -12,9 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
-from random import SystemRandom
-from rstr import Rstr
+import random
 import string
 
 __all__ = ['CryptoString']
@@ -24,14 +22,11 @@ class CryptoString(object):
 
     def __init__(self):
         self._pool = string.ascii_letters + string.digits + string.punctuation
-        self._rs = Rstr(SystemRandom())
+        self._random = random.SystemRandom()
 
-    def get_crypto_string(self, len=24):
+    def get_crypto_string(self, length=24):
         """
-        Create and return a random cryptographic string,
-        of the ``len`` length.
+        Create and return a random cryptographic string of length ``length``.
         """
-
-        if len < 24:
-            len = 24
-        return self._rs.rstr(self._pool, len)
+        return ''.join(self._random.choice(self._pool)
+                       for _ in range(max(24, length)))

requirements.txt

@@ -6,7 +6,6 @@ cryptography==2.3.1
 python-dateutil==2.7.3
 
 # External dependencies
-rstr==2.2.6
 git+https://github.com/openstack/airship-deckhand.git@49ad9f38842f7f1ecb86d907d86d332f8186eb8c
 git+https://github.com/openstack/airship-shipyard.git@44f7022df6438de541501c2fdd5c46df198b82bf#egg=shipyard_client&subdirectory=src/bin/shipyard_client
 git+https://github.com/openstack/airship-promenade.git@a6e8fdbe22bd153c78a008b92cd5d1c245bc63e3