Update all examples to assume Python 3 by default

[ss10sb]

I think it might be worth adding a blurb early on (maybe in the 'creating a basic inventory file' part) about setting ansible to use python 3 by default (for distros that no longer come with 2.7).

For [example], it could be as simple as mentioning you can add a couple of lines to the inventory file like:
[example:vars]
ansible_python_interpreter=/usr/bin/python3

Or even directly to the host line. Just to get things started and not fail immediately on the ping example :)

[geerlingguy]

@ss10sb - Good idea! Right now the only OSes where this is a concern are Ubuntu 16 and 18... but it will become more and more important.

I think I'll add a note/warning in there about it. Hopefully Ansible itself will eventually get more intelligent about detecting Python 3 installed on a system :/

See related issue upstream: ansible/ansible#26163

[geerlingguy]

It's now an issue on Debian 10, which includes Python 3 as the default (though I think it aliases python to python3...? Not sure about pip).

So yes, I think at some point I'm going to try to figure out how to introduce this a little more gently. Otherwise, I wonder if support is now better, as according to the docs, Ansible will automatically use python3 on certain managed OSes... https://docs.ansible.com/ansible/latest/reference_appendices/python_3_support.html

I'll have to do some testing to see if I still need to do my hacky hack:

  pre_tasks:
    - name: Install Python if not already present.
      raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal)
      changed_when: false

    - name: Gather facts after Python is definitely present.
      setup:

[goagex]

Hi!

I have found an issue installing pip via apt on Debian 10 (apt-get install python3-pip)
The issue is that you get a old version of pip3 (like all debian packages)
No wrong in that, but if you want to upgrade pip-installed packages later on this breaks, as pip3 is also upgraded.

A solution for this is to install your ansible node with only pip(3)-packages.
You install as few as possible via apt.

apt-get update
apt-get install python3-distutils curl sshpass

# Download and install pip the official pip way
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3 get-pip.py

# Install needed pip3 packages
pip3 install pynacl asn1crypto bcrypt httplib2 paramiko
pip3 install ansible

Upgrade of all pip-installed packages is now easy:

pip list --outdated --format=freeze | grep -v '^\-e' | cut -d = -f 1  | xargs -n1 pip install -U

Command taken from Stack Overflow: How to upgrade all Python packages with pip?

This way your ansible-server is installed with only python3, no python2 needed at all.

ansible 2.8.7
config file = /etc/ansible/ansible.cfg
configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
ansible python module location = /usr/local/lib/python3.7/dist-packages/ansible
executable location = /usr/local/bin/ansible
python version = 3.7.3 (default, Apr 3 2019, 05:39:12) [GCC 8.3.0]

When you install ansible via pip, you will not get the default ansible.cfg in /etc/ansible.
Just create the folders yourself, and add the default ansible.cfg

[geerlingguy]

Updating issue title, and also noting changes from closed PR #148.

[geerlingguy]

Through various other issues, I've actually updated almost everything to default to Python 3 now, especially after updating examples to use Debian 10 and Ubuntu 20.04 (both of which have Python 3 by default and make it slightly harder to use Python 2).

So I think I can confidently close out this issue after removing one more change that is not necessary anymore (see commit coming soon). There are still a few places in the book where Python 2 is used for CentOS 7 examples, but a couple of those have issues open for them or I'll work on updating them (e.g. switching to CentOS 8) at a later date.