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

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Updated at March 3, 2025

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

To create an infrastructure for your website with load balancing in three availability zones with an Application Load Balancer using Terraform:

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

Get your cloud ready

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 infrastructure support cost includes:

Fee for continuously running VMs (see Yandex Compute Cloud pricing ).
Fee for a dynamic public IP address (see Yandex Virtual Private Cloud pricing).
Fee for load balancing (see Application Load Balancer pricing).
Fee for public DNS queries and DNS zones if using Yandex Cloud DNS (see Cloud DNS pricing).

With Terraform, you can quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. These files store the infrastructure description written in HashiCorp Configuration Language (HCL). If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.

Terraform is distributed under the Business Source License. The Yandex Cloud provider for Terraform is distributed under the MPL-2.0 license.

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

To host a fault-tolerant website in a VM group with load balancing with Application Load Balancer 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 your infrastructure description files:

Ready-made configuration

Manually

Clone the repository with configuration files.

git clone https://github.com/yandex-cloud-examples/yc-website-high-availability-with-alb.git

Navigate to the repository directory. Make sure it contains the following files:
- application-load-balancer-website.tf: New infrastructure configuration.
- application-load-balancer-website.auto.tfvars: User data file.

Create a folder for configuration files.

In the folder, create:

application-load-balancer-website.tf: New infrastructure configuration file:

application-load-balancer-website.tf

# Declaring variables for confidential parameters

variable "folder_id" {
  type = string
}

variable "vm_user" {
  type = string
}

variable "ssh_key_path" {
  type      = string
  sensitive = true
}

variable "domain" {
  type      = string
}

# Adding other variables

locals {
  sa_name      = "ig-sa"
  network_name = "network1"
  subnet_name1 = "subnet-1"
  subnet_name2 = "subnet-2"
  subnet_name3 = "subnet-3"
}

# Configuring a provider

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

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

# Creating a service account and assigning permissions

resource "yandex_iam_service_account" "ig-sa" {
  name = local.sa_name
}

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

# Creating a cloud network and subnets

resource "yandex_vpc_network" "network-1" {
  name = local.network_name
}

resource "yandex_vpc_subnet" "subnet-1" {
  name           = local.subnet_name1
  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           = local.subnet_name2
  zone           = "ru-central1-b"
  network_id     = yandex_vpc_network.network-1.id
  v4_cidr_blocks = ["192.168.2.0/24"]
}

resource "yandex_vpc_subnet" "subnet-3" {
  name           = local.subnet_name3
  zone           = "ru-central1-d"
  network_id     = yandex_vpc_network.network-1.id
  v4_cidr_blocks = ["192.168.3.0/24"]
}

# Create security groups

resource "yandex_vpc_security_group" "alb-sg" {
  name        = "alb-sg"
  network_id  = yandex_vpc_network.network-1.id

  egress {
    protocol       = "ANY"
    description    = "any"
    v4_cidr_blocks = ["0.0.0.0/0"]
    from_port      = 1
    to_port        = 65535
  }

  ingress {
    protocol       = "TCP"
    description    = "ext-http"
    v4_cidr_blocks = ["0.0.0.0/0"]
    port           = 80
  }

  ingress {
    protocol       = "TCP"
    description    = "ext-https"
    v4_cidr_blocks = ["0.0.0.0/0"]
    port           = 443
  }

  ingress {
    protocol          = "TCP"
    description       = "healthchecks"
    predefined_target = "loadbalancer_healthchecks"
    port              = 30080
  }
}

resource "yandex_vpc_security_group" "alb-vm-sg" {
  name        = "alb-vm-sg"
  network_id  = yandex_vpc_network.network-1.id

  ingress {
    protocol          = "TCP"
    description       = "balancer"
    security_group_id = yandex_vpc_security_group.alb-sg.id
    port              = 80
  }

  ingress {
    protocol       = "TCP"
    description    = "ssh"
    v4_cidr_blocks = ["0.0.0.0/0"]
    port           = 22
  }
}

# Creating an instance group for a website

resource "yandex_compute_image" "lemp" {
  source_family = "lemp"
}

resource "yandex_compute_instance_group" "alb-vm-group" {
  name               = "alb-vm-group"
  folder_id          = var.folder_id
  service_account_id = yandex_iam_service_account.ig-sa.id
  instance_template {
    platform_id        = "standard-v2"
    service_account_id = yandex_iam_service_account.ig-sa.id
    resources {
      core_fraction = 5
      memory        = 1
      cores         = 2
    }

    boot_disk {
      mode = "READ_WRITE"
      initialize_params {
        image_id = yandex_compute_image.lemp.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,yandex_vpc_subnet.subnet-3.id]
      nat                = true
      security_group_ids = [yandex_vpc_security_group.alb-vm-sg.id]
    }

    metadata = {
      user-data = "#cloud-config\nusers:\n  - name: ${var.vm_user}\n    groups: sudo\n    shell: /bin/bash\n    sudo: ['ALL=(ALL) NOPASSWD:ALL']\n    ssh_authorized_keys:\n      - ${file("${var.ssh_key_path}")}"
    }
  }

  scale_policy {
    fixed_scale {
      size = 3
    }
  }

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

  deploy_policy {
    max_unavailable = 1
    max_expansion   = 0
  }

  application_load_balancer {
    target_group_name = "alb-tg"
  }
}

# Creating a backend group

resource "yandex_alb_backend_group" "alb-bg" {
  name                     = "alb-bg"
  http_backend {
    name                   = "backend-1"
    port                   = 80
    target_group_ids       = [yandex_compute_instance_group.alb-vm-group.application_load_balancer.0.target_group_id]
    healthcheck {
      timeout              = "10s"
      interval             = "2s"
      healthcheck_port     = 80
      http_healthcheck {
        path               = "/"
      }
    }
  }
}

# Creating an HTTP router and a virtual host

resource "yandex_alb_http_router" "alb-router" {
  name   = "alb-router"
}

resource "yandex_alb_virtual_host" "alb-host" {
  name           = "alb-host"
  http_router_id = yandex_alb_http_router.alb-router.id
  authority      = [var.domain, "www.${var.domain}"]
  route {
    name = "route-1"
    http_route {
      http_route_action {
        backend_group_id = yandex_alb_backend_group.alb-bg.id
      }
    }
  }
}

# Creating an L7 load balancer

resource "yandex_alb_load_balancer" "alb-1" {
  name               = "alb-1"
  network_id         = yandex_vpc_network.network-1.id
  security_group_ids = [yandex_vpc_security_group.alb-sg.id]

  allocation_policy {
    location {
      zone_id   = "ru-central1-a"
      subnet_id = yandex_vpc_subnet.subnet-1.id
    }

    location {
      zone_id   = "ru-central1-b"
      subnet_id = yandex_vpc_subnet.subnet-2.id
    }

    location {
      zone_id   = "ru-central1-d"
      subnet_id = yandex_vpc_subnet.subnet-3.id
    }
  }

  listener {
    name = "alb-listener"
    endpoint {
      address {
        external_ipv4_address {
        }
      }
      ports = [ 80 ]
    }
    http {
      handler {
        http_router_id = yandex_alb_http_router.alb-router.id
      }
    }
  }
}

# Creating a DNS zone

resource "yandex_dns_zone" "alb-zone" {
  name        = "alb-zone"
  description = "Public zone"
  zone        = "${var.domain}."
  public      = true
}

# Create resource records in a DNS zone

resource "yandex_dns_recordset" "rs-1" {
  zone_id = yandex_dns_zone.alb-zone.id
  name    = "${var.domain}."
  ttl     = 600
  type    = "A"
  data    = [yandex_alb_load_balancer.alb-1.listener[0].endpoint[0].address[0].external_ipv4_address[0].address]
}

resource "yandex_dns_recordset" "rs-2" {
  zone_id = yandex_dns_zone.alb-zone.id
  name    = "www"
  ttl     = 600
  type    = "CNAME"
  data    = [ var.domain ]
}

application-load-balancer-website.auto.tfvars: User data file:

application-load-balancer-website.auto.tfvars

folder_id    = "<folder_ID>"
vm_user      = "<instance_username>"
ssh_key_path = "<path_to_public_SSH_key>"
domain       = "<domain>"

For more information about the properties of Terraform resources, see these Terraform guides:

In the application-load-balancer-website.auto.tfvars file, set the following user-defined properties:
- folder_id: Folder ID.
- vm_user: VM username.
- ssh_key_path: Path to the public SSH key that is required to authenticate the user on the VM. For more information, see Creating an SSH key pair.
- domain: Domain name, e.g., alb-example.com.
Create the 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:

On the Virtual machines tab, click the VM name in the list.
Copy Public IPv4 address from the Network section.
Connect to the VM over 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.

Run a fault tolerance test

In the management console, select Compute Cloud.
Go to the page of the VM from the previously created group.
Copy Public IPv4 address from the Network section.
Connect to the VM over SSH.
Stop the web service to simulate a failure on the web server:
```
sudo service nginx stop
```
Open your website in a browser. The website should open, even though one of the web servers has failed.
After the check is complete, restart the web service:
```
sudo service nginx start
```

How to delete the resources you created

To stop paying for the resources you created:

Open the application-load-balancer-website.tf configuration file and delete the new infrastructure description 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 Application Load Balancer using Terraform

Get your cloud ready

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 Application Load Balancer using Terraform

Get your cloud readyGet your cloud ready

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?

Get your cloud ready

Required paid resources

Create an infrastructure

Upload the website files

Run a fault tolerance test

How to delete the resources you created

See also