CUTTING EDGE

Clicking in Horizon and entering CLI commands are two main ways of using an OpenStack system. They are well suited to interactively executing one command at a time but do not scale up easily. A tool such as Terraform, by HashiCorp corporation, provides an alternative to manual ways of introducing cascading changes. Here is how you could, say, create several instances at once:

• Define parameters for the creation of one instance
• save them in a Terraform configuration file and
• let Terraform automatically repeat it the prescribed number of times.

The plan is to install Terraform, get OpenStack token, enter it into the configuration file and execute. You will then be able to effectively use Terraform within the Creodias cloud. For instance, with Terraform you can

• automate creation of a multitude of virtual machines, each with their own floating IPs, DNS and network functions or
• automate creation of Kubernetes clusters

and so on.

What We Are Going To Do

• Install Terraform as a root user
• Reconnect to the cloud
• Download OpenStack token
• Set up the configuration file and initialize Terraform
• Create Terraform code
• Explain the meaning of the variables used
• Execute the Terraform script

Prerequisites

No. 1 Account

You need a Creodias hosting account with access to the Horizon interface: https://horizon.cloudferro.com/auth/login/?next=/. In particular, you will need the password for the account so have it ready in advance.

No. 2 Installed version of Linux

You can use your current Linux installation, however, in this article we shall start with a clean slate. Create a new VM with Ubuntu as defined in this article:

How to create a Linux VM and access it from Linux command line on Creodias.

No. 3 Installed OpenStackClient for Linux

To get token from the cloud, you will first need to enable access from the Ubuntu VM you just created:

How to install OpenStackClient for Linux on Creodias

That article consists of two parts:

Part 1: Install Python and its virtual environment

In the article, you will have executed the following two commands:

python3 -m venv openstack_cli # Create virtual environment openstack_cli

source openstack_cli/bin/activate # Activate it

Part 2: Download the so-called “openrc.sh” file

which will prompt you for the account password and then enable connecting to the cloud.

The exact name of the “openrc” file will depend on the server domain you have. If, for example, the domain is “cloud_00123_1”, the file will be called “cloud_00123_1-openrc.sh”. Additionally, if you have been downloading that same file for a couple of times, your operating system may append numbers such as “cloud_00123_1-openrc-1.sh” or similar.

You will use both the Python virtual environment and the downloaded “openrc” file after Terraform has been installed.

Step 1 Install Terraform as a root user

Install the required dependencies using the following command:

sudo apt-get install wget curl unzip software-properties-common gnupg2 -y

Download and add the HashiCorp signed gpg keys to your system. To perform this action, first enter root mode:

sudo su # Enter root mode

curl -fsSL https://apt.releases.hashicorp.com/gpg | apt-key add -

Add the HashiCorp repository to the APT:

sudo apt-add-repository "deb [arch=$(dpkg --print-architecture)] https://apt.releases.hashicorp.com $(lsb_release -cs) main"

The following commands will update Ubuntu, install Terraform and check its version:

apt-get update -y #update Ubuntu

apt-get install terraform -y # install Terraform

terraform -v # check the version

Now exit root mode and become the standard eouser again.

su eouser # Exit root mode

Step 2 Reconnect to the cloud

Working through Prerequisites Nos. 2 and 3, you ended up being connected up to the cloud. That connection is now lost because you have switched to the root user and back again, to the normal eouser for the Creodias cloud. So

1. activate the same virtual environment with a command

source openstack_cli/bin/activate

2. activate connection to the cloud with the command

. cloud_xxxxx_1-openrc.sh

3. enter the account password

4. test to see all flavors available in the system:

openstack flavor list

You are now ready to receive token from the cloud you are working with. The “token” is actually a very long string of characters which serves as kind of password for your code.

Step 3 Download OpenStack token

Get token with the following command:

openstack token issue -f shell -c id

This is the result:

id="gAAAAABj1VTWP_CFhfKv4zWVH7avFUnHYf5J4TvuKG_Md1EdSpBIBZqTVErqVNWCnO-kYq9D7fi33aRCABadsp23-e-lrDFwyZGkfv-d83UkOTsoIuWogupmwx-3gr4wPcsikBvkAMMBD0-XMIkUONAPst6C35QnztSzZmVSeuXOJ33DaGr6yWbY-tNAOpNsk0C9c13U6ROI"

Value of variable id is the token you need. Copy and save it so that you can enter it into the configuration file for Terraform.

Step 4 Set up the configuration file and initialize Terraform

Create new directory where your Terraform files will be stored and switch to it:

mkdir terraform-dir # Name it as you want

cd terraform-dir

Create configuration file, yourconffile.tf, and open it in text editor. Here we use nano:

sudo nano yourconffile.tf # Name it as you want

Paste the following into the file:

# Configure the OpenStack Provider

     terraform {

       required_providers {

            openstack = {

              source = "terraform-provider-openstack/openstack"

            }

        }

      }

Save the file (for Nano, use Ctrl-X and Y).

These commands inform Terraform it will work with OpenStack.

Use the following command to initialize Terraform:

terraform init

Terraform will read yourconffile.tf file from the current folder. The actual name does not matter as long as it is the only .tf file in the folder.

You can, of course, use many other .tf files such as

,

• main.tf for the main Terraform program
• variable.tf to define variables

and so on.

The screen after initialization would look like this:

Terraform has been initialized and is working properly with your OpenStack cloud. Now add code to perform some useful tasks.

Step 5 Create Terraform code

Append code to the contents of the yourconffile.tf. It will generate four virtual machines as specified in the value of variable count. The entire file yourconffile.tf should now look like this:

# Configure the OpenStack Provider

terraform {

  required_providers {

    openstack = {

      source = "terraform-provider-openstack/openstack"

    }

   }

  }

provider "openstack" {

          user_name = "absdefr@xxyyzz23.com"

          tenant_name = "cloud_00aaa_1"

          auth_url = "https://keystone.cloudferro.com:5000/v3"

          domain_name = "cloud_00aaa_1"

          token = "gAAAAABj1VYdoyiFeJV6_paeAWRd1U9ljgTeNPIQ8NfC2EIzaR-CkAG8AFuBVlj6UoSTbm2jEcjjYk-ShqUTRHNKBNYgSpzJ2CqJT1hgBfZdh3BUKXASOa-PIKSO5dxTOL_DvN0NN2YGHZH49LJS513NxssGDAvSkWOuZ_iIAHq3gHo2omgktq0JrM7KLMkyJ_THrvLmn7xC"

          }

resource "openstack_compute_instance_v2" "test-terra" {

count = 4

name = "test-instance-${count.index}"

image_id = "d7ba6aa0-d5d8-41ed-b29b-3f5336d87340"

flavor_id = "eo2.medium"

security_groups = [

"default", "allow_ping_ssh_icmp_rdp" ]

network {

name = "eodata_00aaa_3"

}

network {

name = "cloud_00aaa_3"

}

}

The meaning of the variables used

The meaning of the variables used is as follows:

user_name

    User name with which you log in into the Creodias account. You can use email address here as well.

tenant_name

    Starts with cloud_00. You can see it in the upper left corner of the Horizon window.

domain_name

    If you have only one project in the domain, this will be identical to the tenant_name from above.

token

    The id value you got from command openstack token issue.

count

    How many times to repeat the operation (in this case, four new virtual machines to create)

name

    The name of each VM; here it is differentiated by adding an ordinal number at the end of the name, for example, test-instance-1, test-instance-0, test-instance-2, test-instance-3.

image_id

    The name or ID code for an operating systems image you get with command Compute -> Images. For example, if you choose Ubuntu 20.04 LTS image, its ID is d7ba6aa0-d5d8-41ed-b29b-3f5336d87340.

flavor_id

    Name of the flavor that each M will have. You get these names from command openstack flavor list.

security_groups

    Here, it is an array of two security groups – default and allow_ping_ssh_icmp_rdp. These are the basic security groups that should be used as a start for all VMs.

network

    Name of the network to use. In this case, we include network eodata_00aaa_3 for eodata and cloud_00aaa_3 for general communication within the cloud.

Step 6 Execute the Terraform script

Here is how Terraform will create four instances of Ubuntu 20.04 LTS. Command apply will execute the script; when asked for confirmation to proceed, type yes to start the operation:

terraform apply

Type

yes

It will create four VMs as defined by variable count.

You should see output similar to this:

This is how you would see those virtual machines in Horizon:

If you wanted to revert the actions, that is, delete the VMs you have just created, the command would be:

terraform destroy

Again, type yes to start the operations.

What To Do Next

Of particular interest would be the following CLI commands for Terraform:

plan

    Shows what changes Terraform is going to apply for you to approve.

validate

    Check whether the configuration is valid.

show

    Show the current state or a saved plan.

Use command

terraform -help

to learn other commands Terraform can offer.