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In this article:

    Building VMs with Terraform

    Terraform is an open source Infrastructure as code (IaC) or infrastructure as code software created by HashiCorp. It allows users to define and provide data center infrastructure using a declarative configuration language known as the HashiCorp configuration language, or optionally JSON.

    It is assumed that Terraform has already been prepared and configured according to the instructions .

    Attention

    At the time of this writing, the current version of Terraform is 0.12.24.

    Terraform cannot create a virtual machine with a disk type, as this is due to the versioning of the OpenStack API. The correct way is to create a disk, then create a virtual machine.

    Configuration creation

    First, you should describe the configuration of the virtual infrastructure. For this, the main.tf file is created in the directory with terraform configuration files, and the following data is added:

    Key pair description

    This code segment is responsible for the ssh key:

     resource "openstack_compute_keypair_v2" "ssh" {
      # Name of the ssh key,
      # This key will be displayed in the section
      # Cloud computing -> Key pairs
      name = "terraform_ssh_key"
      
    # Path to public key
    # In the example, it is in the same directory as main.tf
      public_key = file ("$ {path.module} /terraform.pem.pub")
    }

    Description of the security group

    Next, you should create a security group, which will be assigned to the VM being created, and allow traffic to be received on ports 22 and 80, and also allow icmp traffic from any source.

     resource "openstack_compute_secgroup_v2" "rules" {
      name = "terraform__security_group"
      description = "security group for terraform instance"
      rule {
        from_port = 22
        to_port = 22
        ip_protocol = "tcp"
        cidr = "0.0.0.0/0"
      }
      rule {
        from_port = 80
        to_port = 80
        ip_protocol = "tcp"
        cidr = "0.0.0.0/0"
      }
      rule {
        from_port = -1
        to_port = -1
        ip_protocol = "icmp"
        cidr = "0.0.0.0/0"
      }
    }

    Block device description

    This segment is responsible for creating a disc.

     resource "openstack_blockstorage_volume_v2" "volume" {
    # Disc name
      name = "storage"
      
    # Type of disk being created
      volume_type = "dp1"
      
    # Disk size
      size = "10"
    
      # uuid image indicator, example uses Ubuntu-18.04-201910
      image_id = "cd733849-4922-4104-a280-9ea2c3145417"
    }

    The available disk types can be viewed using the OpenStack CLI command:

     $ openstack volume type list

    At the time of this writing, the following are available:

    Description

    volume_type Description

    ko1-high-iops, dp1-high-iops

    high-IOPS-SSD drives in MS1 and DP1 zones, respectively

    ko1-ssd, dp1-ssd

    SSD disks in MS1 and DP1 zones respectively

    ssd

    geo-distributed SSD

    ms1, dp1

    hdd disks in MS1 and DP1 zones respectively
    ceph geo-distributed HDD

    Available images and their UUIDs can be viewed with the OpenStack CLI command:

     $ openstack image list

    Flavor description

     # What configuration should be used for the instance (vCPU and RAM size).
    flavor_name = "Basic-1-2-10"

    You can get a list of available configurations through the CLI, with the command

     $ openstack flavor list

    Final configuration view

    The assembled configuration will look like:

     resource "openstack_compute_instance_v2" "instance" {
    # Name of the created VM
      name = "terraform"
    
    # Name and uuid of the OS image
      image_name = "Ubuntu-18.04-201910"
      image_id = "cd733849-4922-4104-a280-9ea2c3145417"
      
    # Instance configuration
      flavor_name = "Basic-1-1-10"
    
    # Public key for access
      key_pair = openstack_compute_keypair_v2.ssh.name
    
    # Specify that when creating to use config drive
      # Without this option, the VM will not be created correctly in networks without DHCP
      config_drive = true
    
    # Assigned to security group for VM
      security_groups = [
       openstack_compute_secgroup_v2.rules.name
      ]
    
    # This example uses ext-net
      network {
        name = "ext-net"
      }
    
      # Block device
      block_device {
        uuid = openstack_blockstorage_volume_v2.volume.id
        boot_index = 0
        source_type = "volume"
        destination_type = "volume"
        delete_on_termination = true
      }
    }

    Additional options

    After creating a VM, it starts preparing it for use. This example shows remote connection and execution of cli commands.

     provisioner "remote-exec" {
    # First describes the connection
        connection {
    # This address can be obtained from the compute node when creating a VM
    # The address itself can be obtained from ext-net
          host = openstack_compute_instance_v2.instance.access_ip_v4
    
    # The user on whose behalf the SSH connection is started
          user = "ubuntu"
    
    # Private key to be used
    # In this example, it is in the same directory as main.tf
          private_key = file ("$ {path.module} /terraform.pem")
        }
    
    # cli commands to use
    # Do not forget that this is an array type and you must enter full text
        inline = [
          "sudo apt-get update",
          "sudo apt-get -y install nginx",
    ]

    You can also display artifacts, for example, the ext-net IP address that the VM received. To do this, add the following:

     output "instances" {
      value = "$ {openstack_compute_instance_v2.instance.access_ip_v4}"
    }

    Infrastructure deployment

    To make sure that the deployment configuration is correct, you should run the command:

     $ terraform plan

    There will be a test connection, checking for the availability of resources, checking the .tf syntax, and a list of changes (add, change, destroy) will be displayed.

    If the test connection is completed successfully, the command is used to deploy the configuration:

     $ terraform apply

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