Google Cloud Platform Guide¶

Introduction¶

Ansible contains modules for managing Google Compute Engine resources, including creating instances, controlling network access, working with persistent disks, and managing load balancers. Additionally, there is an inventory plugin that can automatically suck down all of your GCE instances into Ansible dynamic inventory, and create groups by tag and other properties.

The GCE modules all require the apache-libcloud module, which you can install from pip:

$ pip install apache-libcloud

Credentials¶

To work with the GCE modules, you’ll first need to get some credentials. You can create new one from the console by going to the “APIs and Auth” section and choosing to create a new client ID for a service account. Once you’ve created a new client ID and downloaded (you must click Generate new P12 Key) the generated private key (in the pkcs12 format), you’ll need to convert the key by running the following command:

$ openssl pkcs12 -in pkey.pkcs12 -passin pass:notasecret -nodes -nocerts | openssl rsa -out pkey.pem

There are two different ways to provide credentials to Ansible so that it can talk with Google Cloud for provisioning and configuration actions:

• by providing to the modules directly
• by populating a secrets.py file

- name: Create instance(s)
  hosts: localhost
  connection: local
  gather_facts: no

  vars:
    service_account_email: unique-id@developer.gserviceaccount.com
    pem_file: /path/to/project.pem
    project_id: project-id
    machine_type: n1-standard-1
    image: debian-7

  tasks:

   - name: Launch instances
     gce:
         instance_names: dev
         machine_type: "{{ machine_type }}"
         image: "{{ image }}"
         service_account_email: "{{ service_account_email }}"
         pem_file: "{{ pem_file }}"
         project_id: "{{ project_id }}"

GCE_PARAMS = ('i...@project.googleusercontent.com', '/path/to/project.pem')
GCE_KEYWORD_PARAMS = {'project': 'project_id'}

GCE Dynamic Inventory¶

The best way to interact with your hosts is to use the gce inventory plugin, which dynamically queries GCE and tells Ansible what nodes can be managed.

Note that when using the inventory script gce.py, you also need to populate the gce.ini file that you can find in the contrib/inventory directory of the ansible checkout.

To use the GCE dynamic inventory script, copy gce.py from contrib/inventory into your inventory directory and make it executable. You can specify credentials for gce.py using the GCE_INI_PATH environment variable – the default is to look for gce.ini in the same directory as the inventory script.

Let’s see if inventory is working:

$ ./gce.py --list

You should see output describing the hosts you have, if any, running in Google Compute Engine.

Now let’s see if we can use the inventory script to talk to Google.

$ GCE_INI_PATH=~/.gce.ini ansible all -i gce.py -m setup
hostname | success >> {
  "ansible_facts": {
    "ansible_all_ipv4_addresses": [
      "x.x.x.x"
    ],

As with all dynamic inventory scripts in Ansible, you can configure the inventory path in ansible.cfg. The recommended way to use the inventory is to create an inventory directory, and place both the gce.py script and a file containing localhost in it. This can allow for cloud inventory to be used alongside local inventory (such as a physical datacenter) or machines running in different providers.

Executing ansible or ansible-playbook and specifying the inventory directory instead of an individual file will cause ansible to evaluate each file in that directory for inventory.

Let’s once again use our inventory script to see if it can talk to Google Cloud:

$ ansible all -i inventory/ -m setup
hostname | success >> {
  "ansible_facts": {
    "ansible_all_ipv4_addresses": [
        "x.x.x.x"
    ],

The output should be similar to the previous command. If you’re wanting less output and just want to check for SSH connectivity, use “-m” ping instead.

Use Cases¶

For the following use case, let’s use this small shell script as a wrapper.

#!/usr/bin/env bash
PLAYBOOK="$1"

if [[ -z $PLAYBOOK ]]; then
  echo "You need to pass a playbook as argument to this script."
  exit 1
fi

export SSL_CERT_FILE=$(pwd)/cacert.cer
export ANSIBLE_HOST_KEY_CHECKING=False

if [[ ! -f "$SSL_CERT_FILE" ]]; then
  curl -O http://curl.haxx.se/ca/cacert.pem
fi

ansible-playbook -v -i inventory/ "$PLAYBOOK"

- name: Create instance(s)
  hosts: localhost
  gather_facts: no
  connection: local

  vars:
    machine_type: n1-standard-1 # default
    image: debian-7
    service_account_email: unique-id@developer.gserviceaccount.com
    pem_file: /path/to/project.pem
    project_id: project-id

  tasks:
    - name: Launch instances
      gce:
          instance_names: dev
          machine_type: "{{ machine_type }}"
          image: "{{ image }}"
          service_account_email: "{{ service_account_email }}"
          pem_file: "{{ pem_file }}"
          project_id: "{{ project_id }}"
          tags: webserver
      register: gce

    - name: Wait for SSH to come up
      wait_for: host={{ item.public_ip }} port=22 delay=10 timeout=60
      with_items: gce.instance_data

    - name: Add host to groupname
      add_host: hostname={{ item.public_ip }} groupname=new_instances
      with_items: gce.instance_data

- name: Manage new instances
  hosts: new_instances
  connection: ssh
  sudo: True
  roles:
    - base_configuration
    - production_server

- name: Setup web servers
  hosts: tag_webserver
  gather_facts: no

  vars:
    machine_type: n1-standard-1 # default
    image: debian-7
    service_account_email: unique-id@developer.gserviceaccount.com
    pem_file: /path/to/project.pem
    project_id: project-id

  roles:

    - name: Install lighttpd
      apt: pkg=lighttpd state=installed
      sudo: True

    - name: Allow HTTP
      local_action: gce_net
      args:
        fwname: "all-http"
        name: "default"
        allowed: "tcp:80"
        state: "present"
        service_account_email: "{{ service_account_email }}"
        pem_file: "{{ pem_file }}"
        project_id: "{{ project_id }}"