Cannot install Ansible

Question

So I am creating a packer template for docker with the image php:7.0-apache. I added a shell provisioner where I try to install ansible so I can provision the image:

{
            "type": "shell",
            "inline": [
                "apt-get -y update",
                "apt-get install -y software-properties-common",
                "apt-add-repository ppa:ansible/ansible",
                "apt-get -y update",

                "apt-get install -y sudo",
                "apt-get install -y ansible"
            ]
        },

However, I get this error. Why is that?

EDIT: After installing the gnupg package, there still seems to be issues that result in the building process to fail:

Answer 1

This is how I managed to test your scenario manually against the php:7.0-apache docker image. Note that this image is based on debian:stretch. In your question, you are following the install guide for ubuntu which will fail anyway in debian stretch.

I'm using the correct scenario below. See the ansible install documentation for more details. I also kept the install of sudo which was in your initial provisioning script.

apt-get update
apt-get install -y gnupg sudo
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 93C4A3FD7BB9C367
echo deb http://ppa.launchpad.net/ansible/ansible/ubuntu trusty main >> /etc/apt/sources.list
apt-get update
apt-get install -y ansible
apt-get clean

After playing this, result:

root@18ab6da8ac92:/var/www/html# ansible --version              
ansible 2.9.4
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.13 (default, Sep 26 2018, 18:42:22) [GCC 6.3.0 20170516]

Now, the above is installing ansible from deb packages that will run in python 2.7 that has been obsoleted. I much rather prefer the following scenario using pip that will install ansible as well but in python3 and does not need to add a supplementary apt repo neither requires to install gnupg

apt-get update
apt-get install -y python3-pip
pip3 install --upgrade pip
pip install ansible
apt-get clean

And the result

root@e6b73a5f1d59:/var/www/html# ansible --version
ansible 2.9.4
  config file = None
  configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.5/dist-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.5.3 (default, Sep 27 2018, 17:25:39) [GCC 6.3.0 20170516]

Answer 2

As it says, No such file or directory: 'gpg', so you probably need to install gnupg before adding the PPA repository:

apt-get install gnupg