Fault-tolerant website with load balancing via Yandex Network Load Balancer using Terraform

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Yandex Cloud

Updated at October 2, 2024

Prepare your cloud
- Required paid resources
Create an infrastructure
Upload the website files
Run a fault tolerance test
How to delete the resources you created

To create a fault-tolerant site with load balancing via Yandex Network Load Balancer using Terraform:

If you no longer need the resources you created, delete them.

Prepare your cloud

Go to the management console and log in to Yandex Cloud or create an account if you do not have one yet.
On the Yandex Cloud Billing page, make sure you have a billing account linked and it has the ACTIVE or TRIAL_ACTIVE status. If you do not have a billing account, create one.

If you have an active billing account, you can go to the cloud page to create or select a folder for your infrastructure to operate in.

Learn more about clouds and folders.

Required paid resources

The cost of hosting a website includes:

Fee for disks and continuously running VMs (see Yandex Compute Cloud pricing).
Fee for using dynamic or static public IP addresses (see Yandex Virtual Private Cloud pricing).
Fee for a network load balancer and traffic balancing (see Network Load Balancer pricing).

Terraform allows you to quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. Configuration files store the infrastructure description in the HashiCorp Configuration Language (HCL). Terraform and its providers are distributed under the Business Source License.

For more information about the provider resources, see the documentation on the Terraform website or the mirror.

If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.

To create an infrastructure using Terraform:

Install Terraform, get the authentication credentials, and specify the source for installing the Yandex Cloud provider (see Configure a provider, Step 1).

Prepare files with the infrastructure description:

Ready-made configuration

Manually

Clone the repository with configuration files:

git clone https://github.com/yandex-cloud-examples/yc-nlb-fault-tolerant-site.git

Go to the directory with the repository. It should now contain the load-balancer.tf file with the new infrastructure configuration.

Create a folder for files.

In the directory, create a configuration file named load-balancer.tf:

load-balancer.tf

terraform {
  required_providers {
    yandex = {
      source  = "yandex-cloud/yandex"
      version = ">= 0.47.0"
    }
  }
}

provider "yandex" {
  zone = "ru-central1-a"
}

variable "folder_id" {
  description = "Yandex Cloud Folder ID where resources will be created"
  default     = "<folder_ID>"
}

resource "yandex_iam_service_account" "ig-sa" {
  name        = "ig-sa"
}

resource "yandex_resourcemanager_folder_iam_member" "editor" {
  folder_id = var.folder_id
  role      = "editor"
  member    = "serviceAccount:${yandex_iam_service_account.ig-sa.id}"
}

resource "yandex_compute_instance_group" "ig-1" {
  name               = "nlb-vm-group"
  folder_id          = var.folder_id
  service_account_id = "${yandex_iam_service_account.ig-sa.id}"
  instance_template {
    platform_id = "standard-v3"
    resources {
      core_fraction = 20
      memory        = 1
      cores         = 2
    }

    boot_disk {
      mode = "READ_WRITE"
      initialize_params {
        image_id = "<image_ID>"
        type     = "network-hdd"
        size     = 3
      }
    }

    network_interface {
      network_id = "${yandex_vpc_network.network-1.id}"
      subnet_ids = ["${yandex_vpc_subnet.subnet-1.id}","${yandex_vpc_subnet.subnet-2.id}" ]
      nat        = true
    }

    metadata = {
      user-data = "#cloud-config\nusers:\n  - name: <username>\n    groups: sudo\n    shell: /bin/bash\n    sudo: 'ALL=(ALL) NOPASSWD:ALL'\n    ssh-authorized-keys:\n      - ${file("<path_to_public_SSH_key>")}"
    }
  }

  scale_policy {
    fixed_scale {
      size = 2
    }
  }

  allocation_policy {
    zones = ["ru-central1-a", "ru-central1-b"]
  }

  deploy_policy {
    max_unavailable = 1
    max_expansion   = 0
  }

  load_balancer {
    target_group_name = "nlb-tg"
  }
}

resource "yandex_lb_network_load_balancer" "foo" {
  name = "nlb-1"
  listener {
    name = "nlb-listener"
    port = 80
  }
  attached_target_group {
    target_group_id = "${yandex_compute_instance_group.ig-1.load_balancer.0.target_group_id}"
    healthcheck {
      name                = "health-check-1"
      unhealthy_threshold = 5
      healthy_threshold   = 5
      http_options {
        port = 80
      }
    }
  }
}

resource "yandex_vpc_network" "network-1" {
  name = "network1"
}

resource "yandex_vpc_subnet" "subnet-1" {
  name           = "subnet1"
  zone           = "ru-central1-a"
  network_id     = "${yandex_vpc_network.network-1.id}"
  v4_cidr_blocks = ["192.168.1.0/24"]
}

resource "yandex_vpc_subnet" "subnet-2" {
  name           = "subnet2"
  zone           = "ru-central1-b"
  network_id     = "${yandex_vpc_network.network-1.id}"
  v4_cidr_blocks = ["192.168.2.0/24"]
}

For more information about the parameters of resources used in Terraform, see the provider documentation:

Under variable, specify folder_id, i.e., the ID of the folder the resources are created in.
Under metadata, specify the metadata for creating a VM and the contents of the SSH key. Use this format for the key: <any_name>:<SSH_key_contents>. Regardless of the username specified, the key is assigned to the user set in the LAMP (LEMP) image configuration. Such users vary depending on an image. For more information, see Keys processed in public images.

You need to create an SSH key pair youself.
Under boot_disk, specify the ID of a VM image with relevant components:
- LAMP (Linux, Apache, MySQL®, PHP).
- LEMP (Linux, Nginx, MySQL®, PHP).
Create resources:
1. In the terminal, change to the folder where you edited the configuration file.
2. Make sure the configuration file is correct using the command:
```
terraform validate
```
  If the configuration is correct, the following message is returned:
```
Success! The configuration is valid.
```
3. Run the command:
```
terraform plan
```
  The terminal will display a list of resources with parameters. No changes are made at this step. If the configuration contains errors, Terraform will point them out.
4. Apply the configuration changes:
```
terraform apply
```
5. Confirm the changes: type yes in the terminal and press Enter.

After creating the infrastructure, upload the website files.

Upload the website files

To test the web server, upload the website files to each VM. You can use the index.html file from this archive as an example.

For each VM in the created group, do the following:

Get the VM public IP address.
Connect to the VM via SSH.
Grant your user write permissions for the /var/www/html directory:
```
sudo chown -R "$USER":www-data /var/www/html
```
Upload the website files to the VM via SCP.
Linux/macOS

Windows
Use the scp command-line utility:
```
scp -r <path_to_directory_with_files> <VM_user_name>@<VM_IP_address>:/var/www/html
```
Use WinSCP to copy the local file directory to /var/www/html on the VM.

Once you upload all files, run a fault tolerance test.

Run a fault tolerance test

Get the public IP address of any VM from the group you created.
Connect to the VM via SSH.
Stop the web service to simulate a failure on the web server:
LAMP

LEMP
```
sudo service apache2 stop
```
```
sudo service nginx stop
```
Get the listener IP address.
Open the website in the browser using the listener address.

The connection should be successful, even though one of the web servers has failed.
When the check is complete, start the web service again:
LAMP

LEMP
```
sudo service apache2 start
```
```
sudo service nginx start
```

How to delete the resources you created

To shut down the website and stop paying for the resources you created:

Open the load-balancer.tf configuration file and delete the description of the new infrastructure from it.
Apply the changes:
1. In the terminal, change to the folder where you edited the configuration file.
2. Make sure the configuration file is correct using the command:
```
terraform validate
```
  If the configuration is correct, the following message is returned:
```
Success! The configuration is valid.
```
3. Run the command:
```
terraform plan
```
  The terminal will display a list of resources with parameters. No changes are made at this step. If the configuration contains errors, Terraform will point them out.
4. Apply the configuration changes:
```
terraform apply
```
5. Confirm the changes: type yes in the terminal and press Enter.

Fault-tolerant website with load balancing via Yandex Network Load Balancer using Terraform

Prepare your cloud

Required paid resources

Create an infrastructure

Upload the website files

Run a fault tolerance test

How to delete the resources you created

See also

Was the article helpful?

Fault-tolerant website with load balancing via Yandex Network Load Balancer using Terraform

Prepare your cloudPrepare your cloud

Required paid resourcesRequired paid resources

Create an infrastructureCreate an infrastructure

Upload the website filesUpload the website files

Run a fault tolerance testRun a fault tolerance test

How to delete the resources you createdHow to delete the resources you created

See alsoSee also

Was the article helpful?

Prepare your cloud

Required paid resources

Create an infrastructure

Upload the website files

Run a fault tolerance test

How to delete the resources you created

See also