Set up two or more VirtualBoxes using Ubuntu. See the Linux series for step-by-step instructions. Including setting up ssh key on ubu-main and copying it over to ubu-box-1 so we can freely ssh from ubu-main to ubu-box-1.

ubu-main at 192.168.56.2 will be the box we use for management.

ubu-box-1 at 192.168.56.11 will be one of the hosts we would like to manage.

Log in to ubu-main and install Ansible.

Enable Ansible

From now on every time you would like to run ansible you'll log in to ubu-main and you'll have to load the Python virtualenv. It can be done by a simple command:

$ source venv/bin/activate

You don't need to run any of the other command we ran earlier, as those installations are all in this virtual environment.

In order to improve your work-environment you could also add the above line to the end of the .bashrc file in your home directory.

Ping the host using ICMP

Given that we can already ssh into ubu-box-1 this a bit unnecessary, but for the methodology, let's use the command line ping program to see if the "remote" host is accessible on the IP level: (Stop with Ctrl-C)

$ ping 192.168.56.11
PING 192.168.56.11 (192.168.56.11) 56(84) bytes of data.
64 bytes from 192.168.56.11: icmp_seq=1 ttl=64 time=0.370 ms
64 bytes from 192.168.56.11: icmp_seq=2 ttl=64 time=0.991 ms
64 bytes from 192.168.56.11: icmp_seq=3 ttl=64 time=0.976 ms
^C
--- 192.168.56.11 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2026ms
rtt min/avg/max/mdev = 0.370/0.779/0.991/0.289 ms

Just to show you how does it look like when the remote machine is not reachable with the command line ping I tried to ping another IP that is not in use. Again Ctr-C stops it.

$ ping 192.168.56.12

PING 192.168.56.12 (192.168.56.12) 56(84) bytes of data.
From 192.168.56.2 icmp_seq=1 Destination Host Unreachable
From 192.168.56.2 icmp_seq=2 Destination Host Unreachable
From 192.168.56.2 icmp_seq=3 Destination Host Unreachable
^C
--- 192.168.56.12 ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3057ms
pipe 4

Ping the hosts using Ansible

Once we have Ansible installed, and we checked that it can be executed running

$ ansible --version

ansible 2.4.3.0
  config file = None
  configured module search path = ['/home/foo/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /home/foo/venv/lib/python3.6/site-packages/ansible
  executable location = /home/foo/venv/bin/ansible
  python version = 3.6.3 (default, Oct  3 2017, 21:45:48) [GCC 7.2.0]

the first thing to do is to check if we can reach the host(s) by Ansible.

We prepare a configuration file that will list our "inventory", the list of all the hosts we are managing.

inventory.cfg looks like this:

[all]
192.168.56.11

Now we can ping "all" the machines in our inventory by running:

$ ansible -i inventory.cfg all -m ping

192.168.56.11 | FAILED! => {
    "changed": false,
    "module_stderr": "Shared connection to 192.168.56.11 closed.\r\n",
    "module_stdout": "/bin/sh: 1: /usr/bin/python: not found\r\n",
    "msg": "MODULE FAILURE",
    "rc": 0
}

The ping module of Ansible is different from the ping command. It attempts to connect to the remote machines using ssh and then it tries to check if it will be able to execute code on the remote machines.

Our attempt failed because Ansible uses Python 2 to be installed on the remote machines in order to work and Ubuntu 17.04 comes with Python 3 only.

Tell Ansible to use Python 3

Starting from version 2.2.0 of Ansible you can ask it to use Python 3 on the remote machine.

You can do it on the command line, but then you'll have to do it every time you run ansible:

$ ansible -i inventory.cfg all -m ping -e 'ansible_python_interpreter=/usr/bin/python3'

You can do it per machine in the inventory file:

[all]
192.168.56.11 ansible_python_interpreter=/usr/bin/python3

or you can do it for a group of machines in the inventory file:

[all]
192.168.56.11

[all:vars]
ansible_python_interpreter=/usr/bin/python3

Install Python 2 on the hosts

Alternatively you could install Python 2 on each host and we could do it either manually or using Ansible. Here you can see how to do it manually, if that's what you'd like to do.

Install Python 2 on the remote host manually: ssh to remote host and then run sudo apt-get install -y python. This time I've included the full prompt to make it easier to see on which machine do I executed each command:

foo@ubu-main:~$ ssh foo@192.168.56.11
foo@ubu-box-1:~$ sudo apt-get install -y python
...
foo@ubu-box-1:~$ exit

If we try to ping now it should be successful:

$ ansible -i inventory.cfg all -m ping

192.168.56.11 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Remove Python 2

If you'd like to experiment with this, you can remove Python 2 manually with the following commands:

$ sudo apt-get remove --purge  python
$ sudo apt autoremove

You can check the availability of Python 2 by running:

$ python --version
-bash: /usr/bin/python: No such file or directory

as opposed to

$ python --version
Python 2.7.14

when Python 2 is installed.

Then you can see if your process installing Python 2 works.

Ping with Ansible successful

In any case, you need to be able to successfully ping the remote host(s) in order to start using Ansible.

$ ansible -i inventory.cfg all -m ping

192.168.56.11 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}