Use Terraform to manage OpenStack clusters

After having an OpenStack production environment and home lab for a while, I can say with certainty that provisioning workloads and management from both an admin and tenant perspective It is very important.

Terraform is an open source Infrastructure as Code (IaC) software tool for provisioning networks, servers, cloud platforms, etc. Terraform is a declarative language that serves as a blueprint for the infrastructure you are building. You can use Git to manage it, which has a powerful ​GitOps​​ usage scenario.

This article introduces the basics of using Terraform to manage OpenStack clusters. I recreated the OpenStack demo project using Terraform.

Installing Terraform

I use CentOS as a springboard to run Terraform. According to the official documentation, the first step is to add the Hashicorp repository:

$ sudo dnf config-manager --add-repo https://rpm.releases.hashicorp.com/RHEL/hashicorp.repo

Next, install Terraform:

$ sudo dnf install terraform -y

Verify the installation:

$ terraform –version

If you see the version number returned , then you have Terraform installed.

Create a Terraform script for the OpenStack provider

In Terraform, you need a provider, which is a converter that Terraform calls your ​​.tf ​​ Converts to an API call to the platform you are coordinating.

There are three types of providers: official, partner and community:

• Official providers are maintained by Hashicorp.
• Partner providers are maintained by technology companies that work with Hashicorp.
• Community providers are maintained by open source community members.

There is a good community provider of OpenStack in this ​​link​​​. To use this provider, create a ​​.tf​​​ file and name it ​​main.tf​​.

$ vi main.tf

Add the following content in ​​main.tf​​:

terraform {
required_version = ">= 0.14.0"
required_providers {
openstack = {
source= "terraform-provider-openstack/openstack"
version = "1.49.0"
}
}
}
provider "openstack" {
user_name = “OS_USERNAME”
tenant_name = “OS_TENANT”
password= “OS_PASSWORD”
auth_url= “OS_AUTH_URL”
region= “OS_REGION”
}

You need to modify ​​OS_USERNAME​​, ​OS_TENANT​​​, ​​OS_PASSWORD​​​, ​​OS_AUTH_URL​​​ and ​​OS_REGION​​ variables To work.

Create a Terraform management file

The focus of the OpenStack management file is to provision external networks, routes, users, images, tenant profiles, and quotas.

This example provides styles, routes to external networks, test images, tenant profiles and users.

First, create an ​​AdminTF​​ directory for provisioning resources:

$ mkdir AdminTF
$ cd AdminTF

In ​​main.tf​​, add The following:

terraform {
required_version = ">= 0.14.0"
required_providers {
openstack = {
source= "terraform-provider-openstack/openstack"
version = "1.49.0"
}
}
}
provider "openstack" {
user_name = “OS_USERNAME”
tenant_name = “admin”
password= “OS_PASSWORD”
auth_url= “OS_AUTH_URL”
region= “OS_REGION”
}
resource "openstack_compute_flavor_v2" "small-flavor" {
name= "small"
ram = "4096"
vcpus = "1"
disk= "0"
flavor_id = "1"
is_public = "true"
}
resource "openstack_compute_flavor_v2" "medium-flavor" {
name= "medium"
ram = "8192"
vcpus = "2"
disk= "0"
flavor_id = "2"
is_public = "true"
}
resource "openstack_compute_flavor_v2" "large-flavor" {
name= "large"
ram = "16384"
vcpus = "4"
disk= "0"
flavor_id = "3"
is_public = "true"
}
resource "openstack_compute_flavor_v2" "xlarge-flavor" {
name= "xlarge"
ram = "32768"
vcpus = "8"
disk= "0"
flavor_id = "4"
is_public = "true"
}
resource "openstack_networking_network_v2" "external-network" {
name = "external-network"
admin_state_up = "true"
external = "true"
segments {
network_type = "flat"
physical_network = "physnet1"
}
}
resource "openstack_networking_subnet_v2" "external-subnet" {
name= "external-subnet"
network_id= openstack_networking_network_v2.external-network.id
cidr= "10.0.0.0/8"
gateway_ip= "10.0.0.1"
dns_nameservers = ["10.0.0.254", "10.0.0.253"]
allocation_pool {
start = "10.0.0.1"
end = "10.0.254.254"
}
}
resource "openstack_networking_router_v2" "external-router" {
name= "external-router"
admin_state_up= true
external_network_id = openstack_networking_network_v2.external-network.id
}
resource "openstack_images_image_v2" "cirros" {
name = "cirros"
image_source_url = "https://download.cirros-cloud.net/0.6.1/cirros-0.6.1-x86_64-disk.img"
container_format = "bare"
disk_format= "qcow2"
properties = {
key = "value"
}
}
resource "openstack_identity_project_v3" "demo-project" {
name = "Demo"
}
resource "openstack_identity_user_v3" "demo-user" {
name = "demo-user"
default_project_id = openstack_identity_project_v3.demo-project.id
password = "demo"
}

Creating a Tenant Terraform File

As a Tenant, you would typically create virtual machines. You also create network and security groups for these virtual machines.

This example uses the user created by the Admin file above.

First, create a ​​TenantTF​​ directory for tenant-related provisioning:

$ mkdir TenantTF
$ cd TenantTF

在 ​​main.tf​​ 中，添加以下内容：

terraform {
required_version = ">= 0.14.0"
required_providers {
openstack = {
source= "terraform-provider-openstack/openstack"
version = "1.49.0"
}
}
}
provider "openstack" {
user_name = “demo-user”
tenant_name = “demo”
password= “demo”
auth_url= “OS_AUTH_URL”
region= “OS_REGION”
}
resource "openstack_compute_keypair_v2" "demo-keypair" {
name = "demo-key"
public_key = "ssh-rsa ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ"
}
resource "openstack_networking_network_v2" "demo-network" {
name = "demo-network"
admin_state_up = "true"
}
resource "openstack_networking_subnet_v2" "demo-subnet" {
network_id = openstack_networking_network_v2.demo-network.id
name = "demo-subnet"
cidr = "192.168.26.0/24"
}
resource "openstack_networking_router_interface_v2" "demo-router-interface" {
router_id = “XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX”
subnet_id = openstack_networking_subnet_v2.demo-subnet.id
}
resource "openstack_compute_instance_v2" "demo-instance" {
name= "demo"
image_id= "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY"
flavor_id = "3"
key_pair= "demo-key"
security_groups = ["default"]
metadata = {
this = "that"
}
network {
name = "demo-network"
}
}

初始化你的 Terraform

创建 Terraform 文件后，你需要初始化 Terraform。

对于管理员：

$ cd AdminTF
$ terraform init
$ terraform fmt

对于租户：

$ cd TenantTF
$ terraform init
$ terraform fmt

命令解释：

• ​​terraform init​​ 从镜像源下载提供者用于置备此项目。
• ​​terraform fmt​​ 格式化文件，以便在仓库中使用。

创建一个 Terraform 计划

接下来，为你创建一个 计划plan，看看将创建哪些资源。

对于管理员：

$ cd AdminTF
$ terraform validate
$ terraform plan

对于租户：

$ cd TenantTF
$ terraform validate
$ terraform plan

命令解释：

• ​​terraform validate​​​ 验证 ​​.tf​​ 语法是否正确。
• ​​terraform plan​​ 在缓存中创建一个计划文件，所有管理的资源在创建和销毁时都可以被跟踪。

应用你的第一个 TF

要部署资源，使用 ​​terraform apply​​ 命令。该命令应用计划文件中的所有资源状态。

对于管理员：

$ cd AdminTF
$ terraform apply

对于租户：

$ cd TenantTF
$ terraform apply

接下来的步骤

之前，我写了一篇关于在树莓派上部署最小 OpenStack 集群的 ​​文章​​​。你可以找到更详细的 ​​Terraform 和 Ansible​​ 配置，并通过 GitLab 实现一些 CI/CD。

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