fabric Import Error: cannot import name 'isMappingType'

Question

I came across this "ImportError: cannot import name 'isMappingType' " in the middle of process to deploy fabfile for a Django Project.

1.Here is the structure of my fabfile.py

from __future__ import with_statement
from fabric.api import *
from fabric.contrib.console import confirm
from fabric.contrib.files import append, exists, sed

env.hosts = ["127.0.0.1"]

env.user = raw_input('Please enter user:')

def deploy():
      sudo("apt-get update -y")
sudo("apt-get install git -y")
sudo("apt-get install postgresql libpq-dev python-dev python-pip -y")

code_dir = 'backend-directory'

if exists(code_dir):
   run('cd %s && git pull' % (code_dir,)) 
else:
   run("git clone git://serveraddress/projects/backend-directory")


with cd(code_dir):
  sudo("pip install virtualenv")
  run("virtualenv -p /usr/bin/python3.4 venv")
  run("source venv/bin/activate")
  #sudo("pip install -r requirements/dev.txt")
  sudo("pip install -r requirements/production.txt")

  with settings(warn_only=True):
    with settings(sudo_user = 'postgres'):
        sudo("psql -c " + '"CREATE USER new_user WITH PASSWORD ' + "'new_password';" + '"')
        sudo("psql -c 'ALTER USER new_user CREATEDB;'")
        sudo("psql -c 'CREATE DATABASE newdb;'")
        sudo("psql -c 'GRANT ALL PRIVILEGES ON DATABASE 'newdb' to new_user;'")

    if run("nginx -v").failed:
        sudo(" apt-get install nginx -y")

code_dir = 'frontend-directory' 

if exists(code_dir):
   run('cd %s && git pull' % (code_dir,)) 
else:
   run("git clone git://serveraddress/frontend-directory")


code_dir = 'backend-directory/project_site'

with cd(code_dir):

    run("python manage.py makemigrations --settings=project.settings.development")
    run("python manage.py migrate --settings=project.settings.development")
    sudo("/etc/init.d/nginx start")

    with settings(warn_only=True):
      if run("find /etc/uwsgi").failed:
          sudo("mkdir /etc/uwsgi")
      if run("find /etc/uwsgi/vassals").failed:
          sudo("mkdir /etc/uwsgi/vassals")
      if run("find /etc/uwsgi/vassals/pam_uwsgi.ini").failed:
          sudo("ln -s ~/backend-direcoty/project_site/pam_uwsgi.ini /etc/uwsgi/vassals/") 

    run("uwsgi --emperor /etc/uwsgi/vassals --uid www-data --gid www-data")

Next, I have executed the below command in virtual env

(venv)praneeth@praneeth-Latitude-E6400 ~/wru-pam $ fab deploy

I got the following traceback:-

Traceback (most recent call last):
  File "/home/praneeth/wru-pam/venv/bin/fab", line 9, in <module>
    load_entry_point('Fabric==1.10.1', 'console_scripts', 'fab')()
  File "/home/praneeth/wru-pam/venv/lib/python3.4/site-packages/pkg_resources/__init__.py", line 474, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/home/praneeth/wru-pam/venv/lib/python3.4/site-packages/pkg_resources/__init__.py", line 2582, in load_entry_point
    return ep.load()
  File "/home/praneeth/wru-pam/venv/lib/python3.4/site-packages/pkg_resources/__init__.py", line 2265, in load
    return self._load()
  File "/home/praneeth/wru-pam/venv/lib/python3.4/site-packages/pkg_resources/__init__.py", line 2268, in _load
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/home/praneeth/wru-pam/venv/lib/python3.4/site-packages/fabric/main.py", line 12, in <module>
    from operator import isMappingType
ImportError: cannot import name 'isMappingType'

What might be the reason for this import error ?

Answer 1

fabric doesn't support Python 3:

Fabric is a Python (2.5-2.7) library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks.

See also other points and workarounds at:

• Python 3 support for fabric
• python3 compatibility?

From what I understand, migrating to invoke is the first thing to consider.

---

Quick test demonstrating the problem:

$ python2.7
>>> from operator import isMappingType
>>>

$ python3.4
>>> from operator import isMappingType
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'isMappingType'