[#]: subject: "Use Terraform to manage an OpenStack cluster"
[#]: via: "https://opensource.com/article/23/1/terraform-manage-openstack-cluster"
[#]: author: "AJ Canlas https://opensource.com/users/ajscanlas"
[#]: collector: "lkxed"
[#]: translator: " "
[#]: reviewer: " "
[#]: publisher: " "
[#]: url: " "

Use Terraform to manage an OpenStack cluster
======

After having an OpenStack production and home lab for a while, I can definitively say that provisioning a workload and managing it from an Admin and Tenant perspective is important.

Terraform is an open source Infrastructure-as-Code (IaC) software tool used for provisioning networks, servers, cloud platforms, and more. Terraform is a declarative language that can act as a blueprint of the infrastructure you're working on. You can manage it with Git, and it has a strong [GitOps][1] use case.

This article covers the basics of managing an OpenStack cluster using Terraform. I recreate the OpenStack Demo project using Terraform.

### Install Terraform

I use CentOS as a jump host, where I run Terraform. Based on 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 a version number in return, you have installed Terraform.

### Create a Terraform script for the OpenStack provider

In Terraform, you need a provider. A provider is a converter that Terraform calls to convert your `.tf` into API calls to the platform you are orchestrating.

There are three types of providers: Official, Partner, and Community:

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

There is a good Community provider for OpenStack in this [link][2]. To use this provider, create a `.tf` file and call it `main.tf`.

```
$ vi main.tf
```

Add the following content to `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 change the **OS_USERNAME**, **OS_TENANT**, **OS_PASSWORD**, **OS_AUTH_URL**, and **OS_REGION** variables for it to work.

### Create an Admin Terraform file

OpenStack Admin files focus on provisioning external networks, routers, users, images, tenant profiles, and quotas.

This example provisions flavors, a router connected to an external network, a test image, a tenant profile, and a user.

First, create an `AdminTF` directory for the provisioning resources:

```
$ mkdir AdminTF

$ cd AdminTF
```

In the `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"
}
```

### Create a Tenant Terraform file

As a Tenant, you usually create VMs. You also create network and security groups for the VMs.

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

First, create a `TenantTF` directory for Tenant-related provisioning:

```
$ mkdir TenantTF
$ cd TenantTF
```

In the `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   = “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"
  }
}
```

### Initialize your Terraform

After creating the Terraform files, you need to initialize Terraform.

For Admin:

```
$ cd AdminTF

$ terraform init

$ terraform fmt
```

For Tenants:

```
$ cd TenantTF

$ terraform init

$ terraform fmt
```

Command explanation:

- `terraform init` downloads the provider from the registry to use in provisioning this project.
- `terraform fmt` formats the files for use in repositories.

### Create a Terraform plan

Next, create a plan for you to see what resources will be created.

For Admin:

```
$ cd AdminTF

$ terraform validate

$ terraform plan
```

For Tenants:

```
$ cd TenantTF

$ terraform validate

$ terraform plan
```

Command explanation:

- `terraform validate` validates whether the `.tf` syntax is correct.
- `terraform plan` creates a plan file in the cache where all managed resources can be tracked in creation and destroy.

### Apply your first TF

To deploy the resources, use the `terraform apply` command. This command applies all resource states in the plan file.

For Admin:

```
$ cd AdminTF

$ terraform apply
```

For Tenants:

```
$ cd TenantTF

$ terraform apply
```

### Next steps

Previously, I wrote an [article][3] on deploying a minimal OpenStack cluster on a Raspberry Pi. You can discover how to have more detailed [Terraform and Ansible][4] configurations and implement some CI/CD with GitLab.

--------------------------------------------------------------------------------

via: https://opensource.com/article/23/1/terraform-manage-openstack-cluster

作者：[AJ Canlas][a]
选题：[lkxed][b]
译者：[译者ID](https://github.com/译者ID)
校对：[校对者ID](https://github.com/校对者ID)

本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出

[a]: https://opensource.com/users/ajscanlas
[b]: https://github.com/lkxed
[1]: https://opensource.com/article/21/3/gitops
[2]: https://registry.terraform.io/providers/terraform-provider-openstack/openstack/1.49.0
[3]: https://opensource.com/article/20/12/openstack-raspberry-pi
[4]: https://www.ansible.com/blog/ansible-vs.-terraform-demystified?intcmp=7013a000002qLH8AAM