Ruamel.yaml.jinja2: typ "jinja2"not recognised on CentOS - python-2.7

Question

I'm writing a script in python to update some YAML config files containing jinja2. I found this answer showing how to do it using ruamel.yaml and ruamel.yaml.jinja2 packages and it works absolutely fine on windows10 using this configuration:
$ python -V
Python 2.7.5
$ python -m pip list
[...]
ruamel.ordereddict 0.4.13
ruamel.yaml 0.15.94
ruamel.yaml.jinja2 0.2.2
[...]
and this code:
from ruamel.yaml import YAML
yamlLoader = YAML(typ='jinja2')
But when I try to use it on a CentOS virtual machine, which is the target environment for this script, I get this error:
File "/opt/salt/mig/cnamts_migrate.py", line 17, in <module>
yamlLoader = YAML(typ='jinja2')
File "/usr/lib64/python2.7/site-packages/ruamel/yaml/main.py", line 138, in __init__
'typ "{}"not recognised (need to install plug-in?)'.format(self.typ)
NotImplementedError: typ "jinja2"not recognised (need to install plug-in?)
I can't find any difference in neither Python configuration nor packages' version.
On CentOS VM:
$ python -V
Python 2.7.5
$ pip list
Package Version
---------------------------- -----------
pip 19.1
ruamel.ordereddict 0.4.13
ruamel.yaml 0.15.94
ruamel.yaml.jinja2 0.2.2
setuptools 41.0.1

Answer 1

This path
/usr/lib64/python2.7/site-packages/ruamel/yaml/main.py
in the error message gives me the impression that you are using a system wide Python installation. You should (IMHO even in a VM) use python virtualenv for any utility (and preferaby one per non-related utility). You don't show the output of pip for your CentOS machine, which is way more interesting than the one on your Windows box.
$ more /etc/centos-release
CentOS Linux release 7.3.1611 (Core)
$ /opt/python/3.7/bin/python -m venv /tmp/so-55900745
$ source /tmp/so-55900745/bin/activate
(so-55900745) $ pip install ruamel.yaml.jinja2
Collecting ruamel.yaml.jinja2
Downloading https://files.pythonhosted.org/packages/4f/b4/9676d4fa53d921f98f40dcda2ecfdb9fba2b68fbdccec3d9d4d2c87d96a7/ruamel.yaml.jinja2-0.2.2-py2.py3-none-any.whl
Collecting ruamel.yaml>=0.15.10 (from ruamel.yaml.jinja2)
Downloading https://files.pythonhosted.org/packages/bb/e3/8c06f90dab796bd5baf5da2482cf919bab3145389196814ec3180d4c7bd5/ruamel.yaml-0.15.94-cp37-cp37m-manylinux1_x86_64.whl (647kB)
100% |████████████████████████████████| 655kB 9.3MB/s
Installing collected packages: ruamel.yaml, ruamel.yaml.jinja2
Successfully installed ruamel.yaml-0.15.94 ruamel.yaml.jinja2-0.2.2
(so-55900745) $ pip list
Package Version
------------------ -------
pip 19.1
ruamel.yaml 0.15.94
ruamel.yaml.jinja2 0.2.2
setuptools 40.8.0
(so-55900745) $ python
Python 3.7.3 (default, Apr 3 2019, 11:33:06)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from ruamel.yaml import YAML
>>> yamlLoader = YAML(typ='jinja2')
>>> exit()
(so-55900745) $ deactivate
$ rm -rf /tmp/so-55900745/
$ virtualenv -p /opt/python/2.7/bin/python /tmp/so-55900745
Running virtualenv with interpreter /opt/python/2.7/bin/python
New python executable in /tmp/so-55900745/bin/python
Installing setuptools, pip, wheel...
done.
$ source /tmp/so-55900745/bin/activate
(so-55900745) $ pip install ruamel.yaml.jinja2
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
Collecting ruamel.yaml.jinja2
Using cached https://files.pythonhosted.org/packages/4f/b4/9676d4fa53d921f98f40dcda2ecfdb9fba2b68fbdccec3d9d4d2c87d96a7/ruamel.yaml.jinja2-0.2.2-py2.py3-none-any.whl
Collecting ruamel.yaml>=0.15.10 (from ruamel.yaml.jinja2)
Downloading https://files.pythonhosted.org/packages/a2/59/e8cb144511e47e068efdb71a85f35d00b32fc5f05a9e9a17df265ec252b5/ruamel.yaml-0.15.94-cp27-cp27mu-manylinux1_x86_64.whl (600kB)
|████████████████████████████████| 604kB 2.0MB/s
Collecting ruamel.ordereddict; platform_python_implementation == "CPython" and python_version <= "2.7" (from ruamel.yaml>=0.15.10->ruamel.yaml.jinja2)
Downloading https://files.pythonhosted.org/packages/f3/2c/fa6d75dc459b371ed3b88fdbf8042785ce1655073c884fd97bdbb9f48e01/ruamel.ordereddict-0.4.13-cp27-cp27mu-manylinux1_x86_64.whl (99kB)
|████████████████████████████████| 102kB 12.7MB/s
Installing collected packages: ruamel.ordereddict, ruamel.yaml, ruamel.yaml.jinja2
Successfully installed ruamel.ordereddict-0.4.13 ruamel.yaml-0.15.94 ruamel.yaml.jinja2-0.2.2
(so-55900745) $ python
Python 2.7.15 (default, Aug 10 2018, 11:41:46)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from ruamel.yaml import YAML
>>> yamlLoader = YAML(typ='jinja2')
>>> exit()
(so-55900745) $ deactivate

Answer 2

I ran into the same error message. but with python3.6.
The fix for me was to pip instead of easy_install.
Here's the easy_install related output:
(env) $ easy_install -q ruamel.yaml.jinja2
(env) $ easy_install -q ruamel.yaml
(env) $ python
Python 3.6.7 (default, Oct 22 2018, 11:32:17)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from ruamel.yaml import YAML
>>> yamlLoader = YAML(typ='jinja2')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "REDACTED/env/lib/python3.6/site-packages/ruamel.yaml-0.15.96-py3.6-linux-x86_64.egg/ruamel/yaml/main.py", line 138, in __init__
'typ "{}"not recognised (need to install plug-in?)'.format(self.typ)
NotImplementedError: typ "jinja2"not recognised (need to install plug-in?)
Here's the same thing installing with pip:
(env) $ pip -q install ruamel.yaml.jinja2
(env) $ pip -q install ruamel.yaml
(env) $ python
Python 3.6.7 (default, Oct 22 2018, 11:32:17)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from ruamel.yaml import YAML
>>> yamlLoader = YAML(typ='jinja2')
>>> print("¯\_(ツ)_/¯")
¯\_(ツ)_/¯
If you are using a setup.py in your project, check out Can I use `pip` instead of `easy_install` for `python setup.py install` dependency resolution?