Remove cryptography > 3 support

- Added the incompatiblity of cryptography to the dockerfile.
- 1.3.10 broke dependencies because the docker didn't pull
the project constraints.
- Added a constraints specific for python2 users, other can continue
using the python3 one.

This should allow:
 - Making sure further version's docker stay compatible
 - easier maintenance of python2 vs python3 compatibility.

This does not fix forward compatiblity with cryptography,
but at least make the current build work.

Dockerfile

@@ -2,15 +2,15 @@ FROM python:2.7-alpine
 
 RUN apk update && apk add --no-cache python-dev gcc git g++ make libffi-dev openssl-dev libxml2 libxml2-dev libxslt libxslt-dev
 
-# 
+#
 # NOTE(mmitchell): Mimick -onbuild using -alpine image.
 #                  ONBUILD statements removed because this is an actual Dockerfile
 #
 RUN mkdir -p /usr/src/app
 WORKDIR /usr/src/app
 
-COPY requirements.txt /usr/src/app/
-RUN pip install --no-cache-dir -r requirements.txt
+COPY requirements.txt constraints-py27.txt /usr/src/app/
+RUN pip install --no-cache-dir -r requirements.txt -c constraints-py27.txt
 
 COPY . /usr/src/app
 #

constraints-py27.txt

@@ -0,0 +1,60 @@
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --no-emit-trusted-host --no-index --output-file=constraints-py27.txt requirements.txt
+#
+-e git+https://github.com/stephanerobert/tftpy.git@master#egg=tftpy
+    # via -r requirements.txt
+appdirs==1.4.4
+    # via twisted
+cffi==1.14.5
+    # via cryptography
+constantly==15.1.0
+    # via twisted
+contextlib2==0.6.0.post1
+    # via
+    #   importlib-resources
+    #   zipp
+cryptography==2.9.2 ; python_version < "3"
+    # via
+    #   -r requirements.txt
+    #   twisted
+enum34==1.1.10
+    # via cryptography
+importlib-resources==3.3.1
+    # via netaddr
+incremental==21.3.0
+    # via twisted
+ipaddress==1.0.23
+    # via cryptography
+lxml==4.6.3
+    # via -r requirements.txt
+netaddr==0.8.0
+    # via -r requirements.txt
+pathlib2==2.3.5
+    # via importlib-resources
+pyasn1==0.4.8
+    # via twisted
+pycparser==2.20
+    # via cffi
+scandir==1.10.0
+    # via pathlib2
+singledispatch==3.6.1
+    # via importlib-resources
+six==1.16.0
+    # via
+    #   cryptography
+    #   pathlib2
+    #   singledispatch
+twisted[conch]==16.6.0
+    # via -r requirements.txt
+typing==3.10.0.0
+    # via importlib-resources
+zipp==1.2.0
+    # via importlib-resources
+zope.interface==5.4.0
+    # via twisted
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

constraints.txt

@@ -2,20 +2,40 @@
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile --no-index --no-emit-trusted-host --output-file constraints.txt requirements.txt
+#    pip-compile --no-emit-trusted-host --no-index --output-file=constraints.txt requirements.txt
 #
 -e git+https://github.com/stephanerobert/tftpy.git@master#egg=tftpy
-appdirs==1.4.3            # via twisted
-asn1crypto==0.24.0        # via cryptography
-cffi==1.11.5              # via cryptography
-constantly==15.1.0        # via twisted
-cryptography==2.3.1       # via twisted
-idna==2.7                 # via cryptography
-incremental==17.5.0       # via twisted
-lxml==4.2.5
-netaddr==0.7.19
-pyasn1==0.4.4             # via twisted
-pycparser==2.19           # via cffi
-six==1.11.0               # via cryptography
+    # via -r requirements.txt
+appdirs==1.4.4
+    # via twisted
+cffi==1.14.5
+    # via cryptography
+constantly==15.1.0
+    # via twisted
+cryptography==2.9.2 ; python_version == "3.5"
+    # via
+    #   -r requirements.txt
+    #   twisted
+importlib-resources==3.2.1
+    # via netaddr
+incremental==21.3.0
+    # via twisted
+lxml==4.6.3
+    # via -r requirements.txt
+netaddr==0.8.0
+    # via -r requirements.txt
+pyasn1==0.4.8
+    # via twisted
+pycparser==2.20
+    # via cffi
+six==1.16.0
+    # via cryptography
 twisted[conch]==16.6.0
-zope.interface==4.5.0     # via twisted
+    # via -r requirements.txt
+zipp==1.2.0
+    # via importlib-resources
+zope.interface==5.4.0
+    # via twisted
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

requirements.txt

@@ -1,4 +1,6 @@
 -e git+https://github.com/stephanerobert/tftpy.git@master#egg=tftpy
+cryptography<3; python_version<'3'
+cryptography<3; python_version=='3.5'
 netaddr>=0.7.13
 Twisted[conch]>=16.6.0, <17.0
 lxml>=3.7

test-constraints-py27.txt

@@ -0,0 +1,130 @@
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --no-emit-trusted-host --no-index --output-file=test-constraints-py27.txt constraints-py27.txt test-requirements.txt
+#
+-e git+https://github.com/stephanerobert/tftpy.git@master#egg=tftpy
+    # via -r constraints-py27.txt
+appdirs==1.4.4
+    # via
+    #   -r constraints-py27.txt
+    #   twisted
+bcrypt==3.1.7
+    # via paramiko
+cffi==1.14.5
+    # via
+    #   -r constraints-py27.txt
+    #   bcrypt
+    #   cryptography
+    #   pynacl
+constantly==15.1.0
+    # via
+    #   -r constraints-py27.txt
+    #   twisted
+contextlib2==0.6.0.post1
+    # via
+    #   -r constraints-py27.txt
+    #   importlib-resources
+    #   zipp
+cryptography==2.9.2 ; python_version < "3"
+    # via
+    #   -r constraints-py27.txt
+    #   paramiko
+    #   twisted
+enum34==1.1.10
+    # via
+    #   -r constraints-py27.txt
+    #   cryptography
+flexmock==0.10.4
+    # via -r test-requirements.txt
+funcsigs==1.0.2
+    # via mock
+importlib-resources==3.3.1
+    # via
+    #   -r constraints-py27.txt
+    #   netaddr
+incremental==21.3.0
+    # via
+    #   -r constraints-py27.txt
+    #   twisted
+ipaddress==1.0.23
+    # via
+    #   -r constraints-py27.txt
+    #   cryptography
+lxml==4.6.3
+    # via
+    #   -r constraints-py27.txt
+    #   ncclient
+mock==3.0.5
+    # via -r test-requirements.txt
+ncclient==0.6.10
+    # via -r test-requirements.txt
+netaddr==0.8.0
+    # via
+    #   -r constraints-py27.txt
+    #   pyeapi
+nose==1.3.7
+    # via -r test-requirements.txt
+paramiko==2.7.2
+    # via ncclient
+pathlib2==2.3.5
+    # via
+    #   -r constraints-py27.txt
+    #   importlib-resources
+pexpect==4.8.0
+    # via -r test-requirements.txt
+ptyprocess==0.7.0
+    # via pexpect
+pyasn1==0.4.8
+    # via
+    #   -r constraints-py27.txt
+    #   twisted
+pycparser==2.20
+    # via
+    #   -r constraints-py27.txt
+    #   cffi
+pyeapi==0.8.4
+    # via -r test-requirements.txt
+pyhamcrest==1.10.1
+    # via -r test-requirements.txt
+pynacl==1.4.0
+    # via paramiko
+scandir==1.10.0
+    # via
+    #   -r constraints-py27.txt
+    #   pathlib2
+selectors2==2.0.2
+    # via ncclient
+singledispatch==3.6.1
+    # via
+    #   -r constraints-py27.txt
+    #   importlib-resources
+six==1.16.0
+    # via
+    #   -r constraints-py27.txt
+    #   bcrypt
+    #   cryptography
+    #   mock
+    #   ncclient
+    #   pathlib2
+    #   pyhamcrest
+    #   pynacl
+    #   singledispatch
+twisted[conch]==16.6.0
+    # via -r constraints-py27.txt
+typing==3.10.0.0
+    # via
+    #   -r constraints-py27.txt
+    #   importlib-resources
+zipp==1.2.0
+    # via
+    #   -r constraints-py27.txt
+    #   importlib-resources
+zope.interface==5.4.0
+    # via
+    #   -r constraints-py27.txt
+    #   twisted
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

test-constraints.txt

@@ -2,33 +2,93 @@
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile --no-index --no-emit-trusted-host --output-file test-constraints.txt test-requirements.txt constraints.txt
+#    pip-compile --no-emit-trusted-host --no-index --output-file=test-constraints.txt constraints.txt test-requirements.txt
 #
 -e git+https://github.com/stephanerobert/tftpy.git@master#egg=tftpy
-appdirs==1.4.3
-asn1crypto==0.24.0
-bcrypt==3.1.4             # via paramiko
-cffi==1.11.5
+    # via -r constraints.txt
+appdirs==1.4.4
+    # via
+    #   -r constraints.txt
+    #   twisted
+bcrypt==3.1.7
+    # via paramiko
+cffi==1.14.5
+    # via
+    #   -r constraints.txt
+    #   bcrypt
+    #   cryptography
+    #   pynacl
 constantly==15.1.0
-cryptography==2.3.1
-flexmock==0.10.2
-idna==2.7
-incremental==17.5.0
-lxml==4.2.5
-mock==2.0.0
-ncclient==0.6.3
-netaddr==0.7.19
+    # via
+    #   -r constraints.txt
+    #   twisted
+cryptography==2.9.2 ; python_version == "3.5"
+    # via
+    #   -r constraints.txt
+    #   paramiko
+    #   twisted
+flexmock==0.10.4
+    # via -r test-requirements.txt
+importlib-resources==3.2.1
+    # via
+    #   -r constraints.txt
+    #   netaddr
+incremental==21.3.0
+    # via
+    #   -r constraints.txt
+    #   twisted
+lxml==4.6.3
+    # via
+    #   -r constraints.txt
+    #   ncclient
+mock==3.0.5
+    # via -r test-requirements.txt
+ncclient==0.6.10
+    # via -r test-requirements.txt
+netaddr==0.8.0
+    # via
+    #   -r constraints.txt
+    #   pyeapi
 nose==1.3.7
-paramiko==2.4.2           # via ncclient
-pbr==4.3.0                # via mock
-pexpect==4.6.0
-ptyprocess==0.6.0         # via pexpect
-pyasn1==0.4.4
-pycparser==2.19
-pyeapi==0.8.2
-pyhamcrest==1.9.0
-pynacl==1.3.0             # via paramiko
-selectors2==2.0.1         # via ncclient
-six==1.11.0
+    # via -r test-requirements.txt
+paramiko==2.7.2
+    # via ncclient
+pexpect==4.8.0
+    # via -r test-requirements.txt
+ptyprocess==0.7.0
+    # via pexpect
+pyasn1==0.4.8
+    # via
+    #   -r constraints.txt
+    #   twisted
+pycparser==2.20
+    # via
+    #   -r constraints.txt
+    #   cffi
+pyeapi==0.8.4
+    # via -r test-requirements.txt
+pyhamcrest==2.0.2
+    # via -r test-requirements.txt
+pynacl==1.4.0
+    # via paramiko
+six==1.16.0
+    # via
+    #   -r constraints.txt
+    #   bcrypt
+    #   cryptography
+    #   mock
+    #   ncclient
+    #   pynacl
 twisted[conch]==16.6.0
-zope.interface==4.5.0
+    # via -r constraints.txt
+zipp==1.2.0
+    # via
+    #   -r constraints.txt
+    #   importlib-resources
+zope.interface==5.4.0
+    # via
+    #   -r constraints.txt
+    #   twisted
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools