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Scheduled scaling of instance groups

Written by
Updated at November 14, 2024

Create a Yandex Compute Cloud instance group and set up scheduled scaling for it. A Yandex Cloud Functions function triggered by a timer will manage the instance group size.

To set up scaling for your instance group using standard tools, such as the management console, CLI, or API:

  1. Prepare your cloud.
  2. Create auxiliary resources.
  3. Create an instance group.
  4. Create Cloud Functions resources.
  5. Test instance group scaling.

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

You can also deploy an infrastructure for scaling your instance group via Terraform using a ready-made configuration file.

Prepare your cloud

Sign up for Yandex Cloud and create a billing account:

  1. Go to the management console and log in to Yandex Cloud or create an account if you do not have one yet.
  2. 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.

We will use a folder named example-folder as an example.

The infrastructure cost includes:

Create auxiliary resources

Create a service account

The service account will be linked to the Compute Cloud instance group and Cloud Functions function.

  1. In the management console, select example-folder.
  2. In the list of services, select Identity and Access Management.
  3. Click Create service account.
  4. In the Name field, specify vm-scale-scheduled-sa.
  5. Click Add role and select the following roles:
    • compute.admin: To manage the instance group.
    • iam.serviceAccounts.user: To link the service account to instances in the group.
    • functions.functionInvoker: To call the Cloud Functions function.
  6. Click Create.

  1. Create a service account:

    yc iam service-account create --name vm-scale-scheduled-sa \
  --folder-name example-folder

    Result:

    id: ajeab0cnib1p********
folder_id: b0g12ga82bcv********
created_at: "2022-03-15T09:44:35.989446Z"
name: vm-scale-scheduled-sa

    For more information about the yc iam service-account create command, see the CLI reference.

  2. Assign the following roles to the service account:

    • compute.admin: To manage the instance group:

      yc resource-manager folder add-access-binding example-folder \
  --service-account-name vm-scale-scheduled-sa \
  --role compute.admin \
  --folder-name example-folder

    • iam.serviceAccounts.user: To link the service account to instances in the group:

      yc resource-manager folder add-access-binding example-folder \
  --service-account-name vm-scale-scheduled-sa \
  --role iam.serviceAccounts.user \
  --folder-name example-folder

    • functions.functionInvoker: To call the Cloud Functions function:

      yc resource-manager folder add-access-binding example-folder \
  --service-account-name vm-scale-scheduled-sa \
  --role functions.functionInvoker \
  --folder-name example-folder

    For more information about the yc resource-manager folder add-access-binding command, see the CLI reference.

  1. Create a service account named vm-scale-scheduled-sa. To do this, use the create REST API method for the ServiceAccount resource or the ServiceAccountService/Create gRPC API call.

  2. Assign the service account the following roles for the current folder:

    • compute.admin: To manage the instance group.
    • iam.serviceAccounts.user: To link the service account to instances in the group.
    • functions.functionInvoker: To call the Cloud Functions function.

    To do this, use the setAccessBindings REST API method for the Folder resource or the FolderService/SetAccessBindings gRPC API call.

Create a cloud network

The instance group will be hosted in the Yandex Virtual Private Cloud cloud network and its subnets.

  1. In the management console, select the example-folder folder.
  2. In the list of services, select Virtual Private Cloud.
  3. At the top right, click Create network.
  4. In the Name field, specify vm-scale-scheduled-network.
  5. Select Create subnets.
  6. Click Create network.

  1. Create a network named vm-scale-scheduled-network:

    yc vpc network create --name vm-scale-scheduled-network \
  --folder-name example-folder

    Result:

    id: enpabce123hd********
folder_id: b0g12ga82bcv********
created_at: "2022-03-15T09:55:50.004472Z"
name: vm-scale-scheduled-network

    For more information about the yc vpc network create command, see the CLI reference.

  2. Create a subnet named vm-scale-scheduled-subnet-a in the ru-central1-a availability zone:

    yc vpc subnet create --name vm-scale-scheduled-subnet-a \
  --folder-name example-folder \
  --network-name vm-scale-scheduled-network --range 192.168.1.0/24 \
  --zone ru-central1-a

    Result:

    id: e1lnabc23r1c********
folder_id: b0g12ga82bcv********
created_at: "2022-03-15T09:56:51.859345Z"
name: vm-scale-scheduled-subnet-a
network_id: enpabce123hd********
zone_id: ru-central1-a
v4_cidr_blocks:
- 192.168.1.0/24

    For more information about the yc vpc subnet create command, see the CLI reference.

  3. Create a subnet named vm-scale-scheduled-network-b in the ru-central1-b availability zone:

    yc vpc subnet create --name vm-scale-scheduled-subnet-b \
  --folder-name example-folder \
  --network-name vm-scale-scheduled-network --range 192.168.2.0/24 \
  --zone ru-central1-b

    Result:

    id: b1csa2b3clid********
folder_id: b0g12ga82bcv********
created_at: "2022-03-15T09:57:48.934429Z"
name: vm-scale-scheduled-subnet-b
network_id: enpabce123hd********
zone_id: ru-central1-b
v4_cidr_blocks:
- 192.168.2.0/24
  1. Create a network named vm-scale-scheduled-network using the create REST API method for the Network resource or the NetworkService/Create gRPC API call.
  2. Create a subnet named vm-scale-scheduled-subnet-a in the ru-central1-a availability zone and vm-scale-scheduled-subnet-b in the ru-central1-b availability zone using the create REST API method for the Subnet resource or the SubnetService/Create gRPC API call.

Create an instance group

An instance group will be created with manual scaling so that a Cloud Functions function can manage the group size.

  1. In the management console, select example-folder.
  2. In the list of services, select Compute Cloud.
  3. In the left-hand panel, select Instance groups.
  4. At the top right, click Create group of virtual machines.
  5. Under Basic parameters:
    • In the Name field, specify vm-scale-scheduled-ig.
    • Select Service account vm-scale-scheduled-sa.
  6. Under Allocation, select ru-central1-a and ru-central1-b in the Availability zone field.
  7. Under Instance template, click Define and do the following in the window that opens:
    • Under Boot disk image, select the Ubuntu 20.04 image.
    • Under Computing resources, specify the following configuration:
      • Platform: Intel Ice Lake.
      • vCPU: 2.
      • Guaranteed vCPU performance: 20%.
      • RAM: 2 GB
    • Under Network settings:
      • In the Network field, select vm-scale-scheduled-network.
      • In the Public address field, select No address.
    • Under Access:
      • In the Service account field, select vm-scale-scheduled-sa.
      • In the Login field, enter the name of the user to be created on the VM. You can come up with any username you like.
      • In the SSH key field, paste the contents of the public SSH key. You can create a key pair by following this guide.
    • Click Save.
  8. Under Allow when creating and updating, specify the following configuration:
    • Add above target value: 2.
    • Reduce below target value: 2.
    • Create simultaneously: 2.
    • Stop simultaneously: 2.
  9. Under Scaling:
    • In the Type field, select Fixed.
    • Specify Size 2.
  10. Click Create.

  1. Get the IDs of the resources you created at the previous steps:

    • vm-scale-scheduled-sa service account ID:

      yc iam service-account get vm-scale-scheduled-sa \
  --folder-name example-folder | grep "^id"

      Result:

      id: ajeab0cnib1p********

      For more information about the yc iam service-account get command, see the CLI reference.

    • vm-scale-scheduled-network network ID:

      yc vpc network get vm-scale-scheduled-network \
  --folder-name example-folder | grep "^id"

      Result:

      id: enpabce123hd********

      For more information about the yc vpc network get command, see the CLI reference.

    • vm-scale-scheduled-subnet-a subnet ID:

      yc vpc subnet get vm-scale-scheduled-subnet-a \
  --folder-name example-folder | grep "^id"

      Result:

      id: e1lnabc23r1c********

      For more information about the yc vpc subnet get command, see the CLI reference.

    • vm-scale-scheduled-subnet-b subnet ID:

      yc vpc subnet get vm-scale-scheduled-subnet-b \
  --folder-name example-folder | grep "^id"

      Result:

      id: b1csa2b3clid********

      For more information about the yc vpc subnet get command, see the CLI reference.

  2. Get the ID of the latest version of the Ubuntu 20.04 LTS public image:

    yc compute image get-latest-from-family ubuntu-2004-lts \
  --folder-id standard-images | grep "^id"

    Result:

    id: fd83n3uou8m0********

    For more information about the yc compute image get-latest-from-family command, see the CLI reference.

  3. Insert the obtained IDs in the specification.yaml file with the VM group specification:

    name: vm-scale-scheduled-ig
service_account_id: <service_ account_ID>
allocation_policy:
   zones:
     - zone_id: ru-central1-a
     - zone_id: ru-central1-b
instance_template:
  platform_id: standard-v3
  resources_spec:
    memory: 2G
    cores: 2
    core_fraction: 20
  boot_disk_spec:
    mode: READ_WRITE
    disk_spec:
      type_id: network-hdd
      size: 15G
      image_id: <ID_of_Ubuntu_20.04_LTS_latest_version>
  network_interface_specs:
   - network_id: <network_ID>
     subnet_ids:
       - <subnet_ID_in_ru-central1-a_zone>
       - <subnet_ID_in_ru-central1-b_zone>
     primary_v4_address_spec: {}
scale_policy:
  fixed_scale:
    size: 2
deploy_policy:
  max_unavailable: 2
  max_creating: 2
  max_expansion: 2
  max_deleting: 2

  4. Create an instance group named vm-scale-scheduled-ig based on specification.yaml:

    yc compute instance-group create --file specification.yaml \
  --folder-name example-folder

    Result:

    done (2m18s)
id: cl0kabcquk1g********
folder_id: b0g12ga82bcv********
...
service_account_id: ajeab0cnib1p********
status: ACTIVE

  1. Get the IDs of the resources you created at the previous steps:

  2. Get the ID of the latest version of the public Ubuntu 20.04 image in the standard-images family using the getLatestByFamily REST API method for the Image resource or the ImageService/GetLatestByFamily gRPC API call.

  3. Insert the obtained IDs in the specification.yaml file with the VM group specification:

    name: vm-scale-scheduled-ig
service_account_id: <service_ account_ID>
allocation_policy:
   zones:
     - zone_id: ru-central1-a
     - zone_id: ru-central1-b
instance_template:
  platform_id: standard-v3
  resources_spec:
    memory: 2G
    cores: 2
    core_fraction: 20
  boot_disk_spec:
    mode: READ_WRITE
    disk_spec:
      type_id: network-hdd
      size: 15G
      image_id: <ID_of_Ubuntu_20.04_LTS_latest_version>
  network_interface_specs:
   - network_id: <network_ID>
     subnet_ids:
       - <subnet_ID_in_ru-central1-a_zone>
       - <subnet_ID_in_ru-central1-b_zone>
     primary_v4_address_spec: {}
scale_policy:
  fixed_scale:
    size: 2
deploy_policy:
  max_unavailable: 2
  max_creating: 2
  max_expansion: 2
  max_deleting: 2

  4. Create an instance group named vm-scale-scheduled-ig based on specification.yaml. To do this, use the createFromYaml REST API method for the InstanceGroup resource or the InstanceGroupService/CreateFromYaml gRPC API call.

Create Cloud Functions resources

Create a function

The function will contain the code with the Yandex Cloud CLI commands that update the instance group.

  1. In the management console, select example-folder.

  2. Select Cloud Functions.

  3. At the top right, click Create function.

  4. In the Name field, specify vm-scale-scheduled-function.

  5. Click Create.

  6. Select the Bash runtime environment.

  7. Enable Add files with code examples.

  8. Click Continue.

  9. Under Editor, select the handler.sh file.

  10. Replace the file contents with the code below:

    # Get ID and current size of the instance group
IG_SPEC=$(yc compute instance-group get --name $IG_NAME --folder-id $FOLDER_ID --format json)
IG_ID=$(jq -r ".id" <<< $IG_SPEC)
IG_SIZE=$(jq -r ".scale_policy.fixed_scale.size" <<< $IG_SPEC)

# Calculate new size for the instance group
if [ $IG_SIZE = $IG_BASE_SIZE ]; then
    IG_SIZE="$(($IG_BASE_SIZE + 1))"
else
    IG_SIZE=$IG_BASE_SIZE
fi

# Update the instance group
yc compute instance-group update --id $IG_ID --scale-policy-fixed-scale-size $IG_SIZE

  11. Under Parameters:

    • Set the Timeout, sec field value to 60.
    • In the Service account field, select vm-scale-scheduled-sa.
    • Under Environment variables, add the following variables:
      • IG_NAME = vm-scale-scheduled-ig.
      • IG_BASE_SIZE = 2.
      • FOLDER_ID = Folder ID. You can get the ID by following this guide.

  12. In the top-right corner, click Save changes.

  1. Create a file named config.pkr.hcl with the following code:

    # Get ID and current size of the instance group
IG_SPEC=$(yc compute instance-group get --name $IG_NAME --folder-id $FOLDER_ID --format json)
IG_ID=$(jq -r ".id" <<< $IG_SPEC)
IG_SIZE=$(jq -r ".scale_policy.fixed_scale.size" <<< $IG_SPEC)

# Calculate new size for the instance group
if [ $IG_SIZE = $IG_BASE_SIZE ]; then
    IG_SIZE="$(($IG_BASE_SIZE + 1))"
else
    IG_SIZE=$IG_BASE_SIZE
fi

# Update the instance group
yc compute instance-group update --id $IG_ID --scale-policy-fixed-scale-size $IG_SIZE

  2. Create a function:

    yc serverless function create vm-scale-scheduled-function \
  --folder-name example-folder

    Result:

    done (1s)
id: d4e7d67ikvmq********
folder_id: b1g9hv2loamq********
...
log_group_id: ckgij6l0845h********
http_invoke_url: https://functions.yandexcloud.net/d4e7d67ikvmq********
status: ACTIVE

  3. Create a function version:

    yc serverless function version create --folder-name example-folder \
  --function-name vm-scale-scheduled-function --runtime bash \
  --source-path ./handler.sh --entrypoint "handler.sh" \
  --execution-timeout 60s \
  --service-account-id <service_account_ID> \
  --environment \
    IG_NAME=vm-scale-scheduled-ig,IG_BASE_SIZE=2,FOLDER_ID=<folder_ID>

    Where:

    • --service-account-id: vm-scale-schedule-sa service account ID. To get the ID, follow the Create a VM group step on the CLI tab.
    • FOLDER_ID in --environment: Folder ID. You can get the ID by following this guide.

    Result:

    done (1s)
id: d4efmv9n3qf1********
function_id: d4e7d67ikvmq********
...
  FOLDER_ID: b1g9hv2loamq********
  IG_BASE_SIZE: "2"
  IG_NAME: vm-scale-scheduled-ig

  1. Create a function named vm-scale-scheduled-function using the create REST API method for the Function resource or the FunctionService/Create gRPC API call. You can find the ID of the created function in the output.

  2. Create a function version using the createVersion REST API method for the Function resource or the FunctionService/CreateVersion gRPC API call. The function version should have the following code:

    # Get ID and current size of the instance group
IG_SPEC=$(yc compute instance-group get --name $IG_NAME --folder-id $FOLDER_ID --format json)
IG_ID=$(jq -r ".id" <<< $IG_SPEC)
IG_SIZE=$(jq -r ".scale_policy.fixed_scale.size" <<< $IG_SPEC)

# Calculate new size for the instance group
if [ $IG_SIZE = $IG_BASE_SIZE ]; then
    IG_SIZE="$(($IG_BASE_SIZE + 1))"
else
    IG_SIZE=$IG_BASE_SIZE
fi

# Update the instance group
yc compute instance-group update --id $IG_ID --scale-policy-fixed-scale-size $IG_SIZE

Create a trigger

A trigger sets conditions for running a function. For scheduled function calls, use a timer trigger.

  1. In the management console, select example-folder.
  2. Select Cloud Functions.
  3. In the left-hand panel, select Triggers.
  4. At the top right, click Create trigger.
  5. Under Basic settings:
    • In the Name field, specify vm-scale-scheduled-trigger.
    • In the Type field, select Timer.
    • In the Launched resource field, select Function.
  6. Under Timer settings, in the Cron expression field, specify */2 * * * ? *. The trigger will fire every two minutes, e.g., at 09:58, 10:00, 10:02, 10:04, etc.
  7. Under Function settings:
    • In the Function field, specify vm-scale-scheduled-function.
    • In the Function version tag field, select $latest.
    • Select Service account vm-scale-scheduled-sa.
  8. Under Dead Letter Queue settings, reset the Service account (Not selected) field.
  9. Click Create trigger.

Run the following command:

yc serverless trigger create timer --folder-name example-folder \
  --name vm-scale-scheduled-trigger \
  --cron-expression "*/2 * * * ? *" \
  --invoke-function-name vm-scale-scheduled-function \
  --invoke-function-tag '$latest' \
  --invoke-function-service-account-name vm-scale-scheduled-sa

Result:

id: a1s22pb0v5i4********
folder_id: b1g9hv2loamq********
created_at: "2022-04-06T14:56:54.253709098Z"
...
      function_tag: $latest
      service_account_id: aje9s4pud13h********
status: ACTIVE

Use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call to create a trigger of the timer type with the */2 * * * ? * cron expression. This trigger will be linked with the vm-scale-scheduled-function function of the $latest version and the vm-scale-scheduled-sa service account.

Test instance group scaling

  1. In the management console, select example-folder.
  2. In the list of services, select Compute Cloud.
  3. In the left-hand panel, select Instance groups.
  4. Select the vm-scale-scheduled-ig group.
  5. Under VM states, make sure the number of instances changes every two minutes: increases from 2 to 3, then decreases from 3 to 2, etc. You can also check if the instance group has been updated by opening the Operations tab.

Run the following command several times:

yc compute instance-group get vm-scale-scheduled-ig \
  --folder-name example-folder

Result:

id: cl1l0ljqbmkp********
folder_id: b1g9hv2loamq********
created_at: "2022-03-28T13:24:20.693Z"
...
managed_instances_state:
  target_size: "2"
  running_actual_count: "2"
...

The value of the target_size field for the group should change from 2 to 3 and back.

Get information about the vm-scale-scheduled-ig instance group multiple times using the get REST API method for the InstanceGroup resource or the InstanceGroupService/Get gRPC API call. The value of the target_size field for the group should change from 2 to 3 and back.

How to delete the resources you created

To stop paying for the resources you created:

  1. Delete the vm-scale-scheduled-trigger trigger.
  2. Delete the vm-scale-scheduled-function function.
  3. Delete the vm-scale-scheduled-ig instance group.

How to create an infrastructure using Terraform

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 set up scaling for your instance group using Terraform:

  1. Install Terraform and specify the source for installing the Yandex Cloud provider (see Configure a provider, step 1).

  2. Prepare files with the infrastructure description:

    1. Create a folder for files.
    2. Download the archive (2 KB).
    3. Unpack the archive to the directory. As a result, it should contain the vm-scale-scheduled.tf configuration file and the vm-scale-scheduled-function.zip archive with the Cloud Functions function code.

    1. Create a folder for files.

    2. In the folder, create:

      • vm-scale-scheduled.tf configuration file

        vm-scale-scheduled.tf
        locals {
  token            = "<OAuth_or_IAM_token>"
  cloud_id         = "<cloud_ID>"
  folder_id        = "<folder_ID>"
  username         = "<VM_user_name>"
  ssh_key_path     = "<path_to_public_SSH_key>"
}

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

provider "yandex" {
  token     = local.token
  cloud_id  = local.cloud_id
  folder_id = local.folder_id
}

resource "yandex_iam_service_account" "vm-scale-scheduled-sa" {
  name      = "vm-scale-scheduled-sa"
}

resource "yandex_resourcemanager_folder_iam_member" "vm-scale-scheduled-sa-role-compute" {
  folder_id = "<folder_ID>"
  role      = "compute.admin"
  member    = "serviceAccount:${yandex_iam_service_account.vm-scale-scheduled-sa.id}"
}

resource "yandex_resourcemanager_folder_iam_member" "vm-scale-scheduled-sa-role-iam" {
  folder_id = "<folder_ID>"
  role      = "iam.serviceAccounts.user"
  member    = "serviceAccount:${yandex_iam_service_account.vm-scale-scheduled-sa.id}"
}

resource "yandex_resourcemanager_folder_iam_member" "vm-scale-scheduled-sa-role-functions" {
  folder_id = "<folder_ID>"
  role      = "functions.functionInvoker"
  member    = "serviceAccount:${yandex_iam_service_account.vm-scale-scheduled-sa.id}"
}

resource "yandex_vpc_network" "vm-scale-scheduled-network" {
  name = "vm-scale-scheduled-network"
}

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

resource "yandex_vpc_subnet" "vm-scale-scheduled-subnet-b" {
  name           = "vm-scale-scheduled-subnet-b"
  zone           = "ru-central1-b"
  v4_cidr_blocks = ["192.168.2.0/24"]
  network_id     = yandex_vpc_network.vm-scale-scheduled-network.id
}

resource "yandex_compute_image" "vm-scale-scheduled-image" {
  source_family = "ubuntu-2004-lts"
}

resource "yandex_compute_instance_group" "vm-scale-scheduled-ig" {
  name               = "vm-scale-scheduled-ig"
  service_account_id = yandex_iam_service_account.vm-scale-scheduled-sa.id

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

  instance_template {
    boot_disk {
      mode = "READ_WRITE"
      initialize_params {
        image_id = yandex_compute_image.vm-scale-scheduled-image.id
        size     = 15
      }
    }

    platform_id = "standard-v3"
    resources {
      cores         = 2
      core_fraction = 20
      memory        = 2
    }

    network_interface {
      network_id = yandex_vpc_network.vm-scale-scheduled-network.id
      subnet_ids = [
        yandex_vpc_subnet.vm-scale-scheduled-subnet-a.id,
        yandex_vpc_subnet.vm-scale-scheduled-subnet-b.id
      ]
    }

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

  scale_policy {
    fixed_scale {
      size = 2
    }
  }

  deploy_policy {
    max_unavailable = 2
    max_creating    = 2
    max_expansion   = 2
    max_deleting    = 2
  }

  depends_on = [
    yandex_resourcemanager_folder_iam_member.vm-scale-scheduled-sa-role-compute,
    yandex_resourcemanager_folder_iam_member.vm-scale-scheduled-sa-role-iam
  ]
}

resource "yandex_function" "vm-scale-scheduled-function" {
  name               = "vm-scale-scheduled-function"
  runtime            = "bash"

  user_hash          = "function-v1"
  entrypoint         = "handler.sh"
  content {
    zip_filename = "vm-scale-scheduled-function.zip"
  }

  execution_timeout  = "60"
  memory             = "128"
  service_account_id = yandex_iam_service_account.vm-scale-scheduled-sa.id

  environment = {
    IG_NAME      = yandex_compute_instance_group.vm-scale-scheduled-ig.name
    IG_BASE_SIZE = "2"
    FOLDER_ID    = local.folder_id
  }

  depends_on = [
    yandex_resourcemanager_folder_iam_member.vm-scale-scheduled-sa-role-functions
  ]
}

resource "yandex_function_trigger" "vm-scale-scheduled-trigger" {
  name = "vm-scale-scheduled-trigger"
  timer {
    cron_expression = "*/2 * * * ? *"
  }
  function {
    id                 = yandex_function.vm-scale-scheduled-function.id
    tag                = "$latest"
    service_account_id = yandex_iam_service_account.vm-scale-scheduled-sa.id
  }

  depends_on = [
    yandex_resourcemanager_folder_iam_member.vm-scale-scheduled-sa-role-functions
  ]
}

      • handler.sh file with the Cloud Functions function code:

        handler.sh

        Warning

        If you are creating a file in Windows, make sure that newline characters are in \n Unix format rather than \r\n. You can replace line breaks in a text editor, such as Notepad++, or with such tools as dos2unix or Tofrodos.

        # Get ID and current size of the instance group
IG_SPEC=$(yc compute instance-group get --name $IG_NAME --folder-id $FOLDER_ID --format json)
IG_ID=$(jq -r ".id" <<< $IG_SPEC)
IG_SIZE=$(jq -r ".scale_policy.fixed_scale.size" <<< $IG_SPEC)

# Calculate new size for the instance group
if [ $IG_SIZE = $IG_BASE_SIZE ]; then
    IG_SIZE="$(($IG_BASE_SIZE + 1))"
else
    IG_SIZE=$IG_BASE_SIZE
fi

# Update the instance group
yc compute instance-group update --id $IG_ID --scale-policy-fixed-scale-size $IG_SIZE

    3. In the folder, create the vm-scale-scheduled-function.zip archive that contains the handler.sh file. Next, delete the handler.sh file outside the archive.

  3. Under vm-scale-scheduled.tf, insert the following values in the locals section:

    • token: OAuth token (if you are using a Yandex account) or Yandex Identity and Access Management token (if you are using a Yandex account or federated account) to access Yandex Cloud. The Identity and Access Management token is valid for up to 12 hours but cannot exceed the federation cookie lifetime.
    • cloud_id: ID of the cloud to create the resources in.
    • folder_id: ID of the folder to create the resources in.
    • username: Name of the user to create in the VM. You can come up with any username you like.
    • ssh_key_path: Path to the file with a public SSH key to authenticate the user on the VM. You can create a key pair by following this guide.

  4. 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.

  5. Test instance group scaling.

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Terraform
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Autoscaling a group of VMs to process messages from a queue