Roots > Trellis > Ansible 2.4 > ERROR! Unexpected Exception, this is probably a bug: No module named six

Question

Context

I'm building a WordPress website with the Roots stack. It creates a virtual machine on my computer via Vagrant, Ansible and VirtualBox.

The Problem

During setup I'm getting this error ERROR! Unexpected Exception, this is probably a bug: No module named six

Downgrading Ansible to 2.3 (sudo pip install ansible==2.3.0.0) resolves this error, but than I cannot run certain commands for newer projects.

Code Sample

$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'bento/ubuntu-16.04'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'bento/ubuntu-16.04' is up to date...
==> default: Setting the name of the VM: example.test
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
    default: Adapter 2: hostonly
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
    default: 
    default: Vagrant insecure key detected. Vagrant will automatically replace
    default: this with a newly generated keypair for better security.
    default: 
    default: Inserting generated public key within guest...
    default: Removing insecure key from the guest if it's present...
    default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
    default: The guest additions on this VM do not match the installed version of
    default: VirtualBox! In most cases this is fine, but in rare cases it can
    default: prevent things such as shared folders from working properly. If you see
    default: shared folder errors, please make sure the guest additions within the
    default: virtual machine match the version of VirtualBox you have installed on
    default: your host and reload your VM.
    default: 
    default: Guest Additions Version: 5.0.26
    default: VirtualBox Version: 5.1
==> default: Setting hostname...
==> default: Configuring and enabling network interfaces...
==> default: Exporting NFS shared folders...
==> default: Preparing to edit /etc/exports. Administrator privileges will be required...
==> default: Mounting NFS shared folders...
==> default: Mounting shared folders...
    default: /vagrant => /home/myuser/Sites/example.com/trellis
==> default: Checking for bindfs in VM...
    default: Package manager detected: apt-get
    default: Fuse kernel module is installed
    default: Fuse kernel module is loaded
==> default: Bindfs seems to not be installed on the virtual machine, installing now
    default: Bindfs 1.12.6 is installed
==> default: Machine is ready to use bindfs!
==> default: Creating bind mounts after synced_folders...
    default: /vagrant-nfs-example.test => /srv/www/example.test/current
    default: /ansible-nfs => /home/vagrant/trellis
    default: /home/vagrant/trellis/bin => /home/vagrant/trellis/bin
==> default: [vagrant-hostmanager:guests] Updating hosts file on active guest virtual machines...
==> default: [vagrant-hostmanager:host] Updating hosts file on your workstation (password may be required)...
==> default: Running provisioner: ansible...
Vagrant has automatically selected the compatibility mode '2.0'
according to the Ansible version installed (2.4.0.0).

Alternatively, the compatibility mode can be specified in your Vagrantfile:
https://www.vagrantup.com/docs/provisioning/ansible_common.html#compatibility_mode

    default: Running ansible-galaxy...
- changing role composer from 1.5.0 to 1.5.0
- downloading role 'composer', owned by geerlingguy
- downloading role from https://github.com/geerlingguy/ansible-role-composer/archive/1.5.0.tar.gz
- extracting composer to /home/myuser/Sites/example.com/trellis/vendor/roles/composer
- composer (1.5.0) was installed successfully
- changing role ntp from 1.3.0 to 1.3.0
- downloading role 'ntp', owned by geerlingguy
- downloading role from https://github.com/geerlingguy/ansible-role-ntp/archive/1.3.0.tar.gz
- extracting ntp to /home/myuser/Sites/example.com/trellis/vendor/roles/ntp
- ntp (1.3.0) was installed successfully
- changing role logrotate from e7a498d to e7a498d
- downloading role 'logrotate', owned by nickhammond
- downloading role from https://github.com/nickhammond/ansible-logrotate/archive/e7a498d.tar.gz
- extracting logrotate to /home/myuser/Sites/example.com/trellis/vendor/roles/logrotate
- logrotate (e7a498d) was installed successfully
- changing role swapfile from 0.4 to 0.4
- downloading role 'swapfile', owned by kamaln7
- downloading role from https://github.com/kamaln7/ansible-swapfile/archive/0.4.tar.gz
- extracting swapfile to /home/myuser/Sites/example.com/trellis/vendor/roles/swapfile
- swapfile (0.4) was installed successfully
- changing role geerlingguy.daemonize from 1.1.1 to 1.1.1
- downloading role 'daemonize', owned by geerlingguy
- downloading role from https://github.com/geerlingguy/ansible-role-daemonize/archive/1.1.1.tar.gz
- extracting geerlingguy.daemonize to /home/myuser/Sites/example.com/trellis/vendor/roles/geerlingguy.daemonize
- geerlingguy.daemonize (1.1.1) was installed successfully
- changing role mailhog from 2.1.0 to 2.1.0
- downloading role 'mailhog', owned by geerlingguy
- downloading role from https://github.com/geerlingguy/ansible-role-mailhog/archive/2.1.0.tar.gz
- extracting mailhog to /home/myuser/Sites/example.com/trellis/vendor/roles/mailhog
- mailhog (2.1.0) was installed successfully
 [WARNING]: - dependency geerlingguy.daemonize from role mailhog differs from
already installed version (1.1.1), skipping

    default: Running ansible-playbook...
[DEPRECATION WARNING]: The use of 'include' for tasks has been deprecated. Use 
'import_tasks' for static inclusions or 'include_tasks' for dynamic inclusions.
 This feature will be removed in a future release. Deprecation warnings can be 
disabled by setting deprecation_warnings=False in ansible.cfg.
ERROR! Unexpected Exception, this is probably a bug: No module named six
to see the full traceback, use -vvv
Ansible failed to complete successfully. Any error output should be
visible above. Please fix these errors and try again.
myser@ubuntu:~/Sites/example.com/trellis$ sudo pip install --ignore-installed six
The directory '/home/myuser/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/myuser/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting six
  Downloading https://files.pythonhosted.org/packages/67/4b/141a581104b1f6397bfa78ac9d43d8ad29a7ca43ea90a2d863fe3056e86a/six-1.11.0-py2.py3-none-any.whl
Installing collected packages: six
Successfully installed six-1.11.0
myuser@ubuntu:~/Sites/example.com/trellis$ sudo -H pip install --ignore-installed six
Collecting six
  Using cached https://files.pythonhosted.org/packages/67/4b/141a581104b1f6397bfa78ac9d43d8ad29a7ca43ea90a2d863fe3056e86a/six-1.11.0-py2.py3-none-any.whl
Installing collected packages: six
Successfully installed six-1.11.0

Debugging - I have Ansible 2.3.x installed on my Ubuntu 17.10 machine. - which pip results in /usr/local/bin/pip - which python results in /usr/bin/python - pip --version results in pip 10.0.1 from /usr/local/lib/python2.7/dist-packages/pip (python 2.7) - python --version results in Python 2.7.14

Attempted Solutions

I've read this GitHub Issue on the official Ansible repository but there was no solution. And this one is a hack, not a proper solution and I'm pretty sure it won't work in my case as it's so integral with the Roots stack.

• I tried this suggestion of sudo easy_install pip which executed successfully but did not resolve the issue.
• I checked for duplicate instances of Python and, as far as I could see there was only one installation.
• I confirmed I am running the latest version of PIP with sudo -H pip install six --upgrade.
  • I also tried python -m pip install six which resulted in Requirement already satisfied: six in /usr/local/lib/python2.7/dist-packages (1.11.0).
• This is essentially a duplicate question. As was this. And this. Aaaand this.
• Most of this, this and this are directly from the Roots Trellis forums but they didn't introduce any new solutions than what I boiled it down to above.

Answer 1

Here is an official explanation in the context of Roots' Trellis.

There were three solutions:

1. Upgrade Trellis.
2. Switch between Ansible versions (sudo pip install ansible==2.3.0.0 or with Homebrew brew search to see available versions and then brew install ansible@2.0 and brew link --force ansible@2.0) as you switch between projects.
3. Or follow these instructions to automatically switch between Ansible versions.