Ansible for GCP : How to setup and access remote inventory Hosts

Setting Ansible on Google Cloud Platform for the first time requires some steps to follow. There may be several ways but i followed the below steps:

Assuming that you have couple of Virtual compute nodes created on your google cloud platform, i will be following the below names for sample references

My virtual instances on GCP are:

my-vmgroup-control-1 : This i am using as a control node. 
my-vmgroup-app-instancegroup-1-lmlv : This is my traget inventory node 1 
my-vmgroup-app-instancegroup-1-nxmr: This is my traget inventory node 2

Lets setup the ansible to work with the inventory nodes and perform our tasks.

1) Setup the ssh key 

2) Add public key to the meta data on GCP cloud at project level.

3) setup the ansible environment

Setup the ssh key

Open the Google cloud platform and go to Virtual instances page.

Select the control node that you have setup and click on SSH button on the right. You can also use gloud command to make a connection and open the terminal.

After you logged in to you machine, run the below command.

ssh-keygen -t rsa -f ~/.ssh/<username> -C <choose the service account name here>

Assuming myserviceuser is the user you would connect to the remote instances which has got all privileges 

Ex:  ssh-keygen -t rsa -f ~/.ssh/myserviceuser -C myserviceuser

 - note: Here i used -C mytestmethod which is going to act like a user which later on you need to use

This will create mytestmethod and mytestmethod.pub files under .ssh folder where the first will be your private key and the later one (.pub extention) will be your public key.

cat ~/.ssh/mytestmethod.pub

-- copy the text above

Add public key to the GCP meta data

Go to GCP console and type metadata in the search.

Select Metadata Compute Engine

click on SSH Keys and click Edit on the top

Click Add ITEM and the empty box place the public key that you copied in the previous step.

Save and see you will have new entry added with name mytestmethod and its key

-- note: This impacts all instances under your project.

Setup the Ansible for accessing the remote hosts

Let us assume that you have ansible installed.

Configure ansible.cfg in your home directory 

$ vi ansible.cfg

[defaults]
host_key_checking=False
inventory=./hosts
ask_become_user=True

Create inventory file

$ vi hosts

[myhostgroup]
my-vmgroup-app-instancegroup-1-lmlv   
my-vmgroup-app-instancegroup-1-nxmr  

Alternately, if the user you chose to connect is a different one other than what you used to login on the control node, then you can add ansible_user to specifically redirect ansible to connect to remote host as the specific user like below

$ vi hosts

[myhostgroup]

my-vmgroup-app-instancegroup-1-lmlv   ansible_user = <specific user>

my-vmgroup-app-instancegroup-1-nxmr  ansible_user = <specific user>

--Note: make sure to have the specific user has all the required privileges so that you can still run your play book.

create a sample yaml to run your task

$ vi play.yml

---

#test payblook

- hosts: "{{group}}"

  gather_facts: False

  serial: 1

  tasks:

   - name: test

     shell: ls -ltr 

     register : a

   - debug: var=a.stdout_lines

Execute the Ansible on control node using the private key:

ansible-playbook play.yml --extra-vars "group=myhostgroup" --key-file ~/.ssh/myserviceuser

-- the above command uses the private key of the control node and connects to the remote host through the public key of the service account defined in meta data.

Hope this article is useful for you. Thank you and appreciate any feedback.