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Creating an instance group connected to a file storage

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Updated at October 17, 2024

One of the ways to handle stateful workloads is saving the application state to a file storage independent of the instance group.

To create an instance group that will automatically connect a common file storage to each of its instances:

  1. By default, all operations in Instance Groups are performed on behalf of a service account. If you don't have a service account, create one.

  2. If you do not have a file storage, create one.

  3. Create an instance group:

    If you do not have the Yandex Cloud command line interface yet, install and initialize it.

    The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

    1. View the description of the CLI command to create an instance group:

      yc compute instance-group create --help

    2. Check if there are any networks in the folder:

      yc vpc network list

      If there are none, create a network.

    3. Select one of the Yandex Cloud Marketplace public images, e.g., Ubuntu 22.04 LTS.

      To get a list of available images using the CLI, run this command:

      yc compute image list --folder-id standard-images

      Result:

      +----------------------+-------------------------------------+--------------------------+----------------------+--------+
|          ID          |                NAME                 |          FAMILY          |     PRODUCT IDS      | STATUS |
+----------------------+-------------------------------------+--------------------------+----------------------+--------+
...
| fdvk34al8k5n******** | centos-7-1549279494                 | centos-7                 | dqni65lfhvv2******** | READY  |
| fdv7ooobjfl3******** | windows-2016-gvlk-1548913814        | windows-2016-gvlk        | dqnnc72gj2is******** | READY  |
| fdv4f5kv5cvf******** | ubuntu-1604-lts-1549457823          | ubuntu-1604-lts          | dqnnb6dc7640******** | READY  |
...
+----------------------+-------------------------------------+--------------------------+----------------------+--------+

    4. Prepare a file with the YAML specification of the instance group and give it a name, e.g., specification.yaml.

      To connect the file storage to VMs in the instance group, add the following to the specification:

      • In the instance_template field, a nested filesystem_specs field containing the description of the file storage:

        instance_template:
  ...
  filesystem_specs:
    - mode: READ_WRITE
      device_name: <VM_device_name>
      filesystem_id: <file_storage_ID>

        Where:

        • mode: File storage access mode, which must be READ_WRITE for both reading and writing.
        • device_name: Device name for connecting the file storage to the VM, e.g., sample-fs. The name may contain lowercase Latin letters, numbers, and hyphens. The first character must be a letter. The last character cannot be a hyphen. The name may be up to 63 characters long.
        • filesystem_id: ID of the file storage. You can view the ID in the management console or using the yc compute filesystem list CLI command.

      • In the #cloud-config section of the instance_template.metadata.user-data field, commands for mounting the file storage to the instance:

        instance_template:
  ...
  metadata:
    user-data: |-
      #cloud-config
      ...
      runcmd:
        - mkdir <VM_mount_point>
        - mount -t virtiofs <VM_device_name> <VM_mount_point>
        - echo "test-fs <VM_mount_point> virtiofs    rw    0   0" | tee -a /etc/fstab

        Where:

        • <VM_mount_point>: Directory on the VM to mount the connected file storage to, e.g., /mnt/vfs0.
        • <VM_device_name>: Device name for connecting the file storage to the VM. The value must match the one specified earlier in the instance_template.filesystem_specs.device_name field.

      YAML specification example:

      name: my-vm-group-with-fs
service_account_id: ajegtlf2q28a********
description: "This instance group was created from YAML config."
instance_template:
  platform_id: standard-v3
  resources_spec:
    memory: 2g
    cores: 2
  boot_disk_spec:
    mode: READ_WRITE
    disk_spec:
      image_id: fd8dlvgiatiqd8tt2qke
      type_id: network-hdd
      size: 32g
  network_interface_specs:
    - network_id: enp9mji1m7b3********
      primary_v4_address_spec: {
        one_to_one_nat_spec: {
          ip_version: IPV4
        }
      }
      security_group_ids:
        - enpuatgvejtn********
  filesystem_specs:
    - mode: READ_WRITE
      device_name: sample-fs
      filesystem_id: epdccsrlalon********
  metadata:
    user-data: |-
      #cloud-config
      datasource:
       Ec2:
        strict_id: false
      ssh_pwauth: no
      users:
      - name: my-user
        sudo: ALL=(ALL) NOPASSWD:ALL
        shell: /bin/bash
        ssh-authorized-keys:
        - <public_SSH_key>
      runcmd:
      - mkdir /mnt/vfs0
      - mount -t virtiofs sample-fs /mnt/vfs0
      - echo "sample-fs /mnt/vfs0 virtiofs    rw    0   0" | tee -a /etc/fstab
deploy_policy:
  max_unavailable: 1
  max_expansion: 0
scale_policy:
  fixed_scale:
    size: 2
allocation_policy:
  zones:
    - zone_id: ru-central1-a
      instance_tags_pool:
      - first
      - second

      This example shows a specification for creating a fixed-size instance group with a file storage connected to the instances.

      For more information about the instance group specification parameters, see Specification of an instance group in YAML format.

    5. Create an instance group in the default folder:

      yc compute instance-group create --file specification.yaml

      This command creates a group of two similar instances with the following configuration:

      • Name: my-vm-group-with-fs.
      • OS: Ubuntu 22.04 LTS.
      • Availability zone: ru-central1-a.
      • vCPUs: 2; RAM: 2 GB.
      • Network HDD: 32 GB.
      • Connected to a file storage. The file storage will be mounted to the /mnt/vfs0 directory of the VMS in the instance group.

      • Each VM of the group will have а public IP address assigned. This way, you can easily connect to the group VM over SSH when checking the result.

        If you create an instance group without public IP addresses, you can still connect to a group VM over SSH by specifying its internal IP address or FQDN instead of the public IP address. However, you can only make such a connection from another virtual machine that has a public IP address and is located in the same Yandex Cloud cloud network as the group VM.

    If you don't have Terraform, install it and configure the Yandex Cloud provider.

    1. In the configuration file, describe the parameters of the resources you want to create:

      resource "yandex_iam_service_account" "ig-sa" {
  name        = "ig-sa"
  description = "Service account for managing the instance group."
}

resource "yandex_resourcemanager_folder_iam_member" "editor" {
  folder_id  = "<folder_ID>"
  role       = "editor"
  member     = "serviceAccount:${yandex_iam_service_account.ig-sa.id}"
  depends_on = [
    yandex_iam_service_account.ig-sa,
  ]
}

resource "yandex_compute_instance_group" "ig-1" {
  name                = "fixed-ig"
  folder_id           = "<folder_ID>"
  service_account_id  = "${yandex_iam_service_account.ig-sa.id}"
  deletion_protection = "<deletion_protection>"
  depends_on          = [yandex_resourcemanager_folder_iam_member.editor]
  instance_template {
    platform_id = "standard-v3"
    resources {
      memory = <GB_of_RAM>
      cores  = <number_of_vCPU_cores>
    }

    boot_disk {
      mode = "READ_WRITE"
      initialize_params {
        image_id = "<image_ID>"
      }
    }

    filesystem {
      mode = "READ_WRITE"
      device_name = "<VM_device_name>"
      filesystem_id = "<file_storage_ID>"
    }

    network_interface {
      network_id         = "${yandex_vpc_network.network-1.id}"
      subnet_ids         = ["${yandex_vpc_subnet.subnet-1.id}"]
      security_group_ids = ["<list_of_security_group_IDs>"]
      nat                = true
    }

    metadata = {
      user-data = "#cloud-config\n  datasource:\n   Ec2:\n    strict_id: false\n  ssh_pwauth: no\n  users:\n  - name: <VM_user_name>\n    sudo: ALL=(ALL) NOPASSWD:ALL\n    shell: /bin/bash\n    ssh-authorized-keys:\n    - <public_SSH_key>\n  runcmd:\n    - mkdir <VM_mount_point>\n    - mount -t virtiofs <VM_device_name> <VM_mount_point>\n    - echo \"sample-fs <VM_mount_point> virtiofs    rw    0   0\" | tee -a /etc/fstab"
    }
  }

  scale_policy {
    fixed_scale {
      size = <number_of_VMs_in_the_group>
    }
  }

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

  deploy_policy {
    max_unavailable = 1
    max_expansion   = 0
  }
}

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 = ["192.168.10.0/24"]
}

      Where:

      • yandex_iam_service_account: Description of the service account. All operations in Instance Groups are performed on behalf of the service account.

        You cannot delete a service account while it is linked to an instance group.

      • yandex_resourcemanager_folder_iam_member: Description of access permissions to the folder the service account belongs to. To be able to create, update, and delete instances in the instance group, assign the editor role to the service account.

      • yandex_compute_instance_group: Description of the instance group:

        • General information about the instance group:
          • name: Name of the instance group.
          • folder_id: Folder ID.
          • service_account_id: Service account ID.
          • deletion_protection: Instance group deletion protection, true or false. You cannot delete an instance group with this option enabled. The default value is false.
        • Instance template:

          • platform_id: Platform.

          • resources: Number of vCPU cores and the amount of RAM available to the VM. The values must match the selected platform.

          • boot_disk: Boot disk settings.

            • mode: Disk access mode, which is either READ_ONLY for reading only or READ_WRITE for both reading and writing.
            • image_id: Selected image ID. You can get the image ID from the list of public images.

          • filesystem: File storage settings.

            • mode: File storage access mode, which must be READ_WRITE for both reading and writing.
            • device_name: Device name for connecting the file storage to the VM, e.g., sample-fs. The name may contain lowercase Latin letters, numbers, and hyphens. The first character must be a letter. The last character cannot be a hyphen. The name may be up to 63 characters long.
            • filesystem_id: ID of the file storage. You can view the ID in the management console or using the yc compute filesystem list CLI command.

          • network_interface: Network settings. Specify the IDs of your network, subnet, and security groups.

          • metadata: You need to provide the following in the metadata:

            • VM user name and public key to enable this user to access the VM via SSH.
            • VM mount point for the file storage, i.e., a directory on the VM to mount the connected file storage to, e.g., /mnt/vfs0.
            • VM device name, i.e., a device name for attaching the file storage to the VM. The value must match the one specified earlier in the device_name field under filesystem.

            For more information, see VM metadata.

        • Policies:

      • yandex_vpc_network: Description of the cloud network.

      • yandex_vpc_subnet: Description of the subnet the instance group will connect to.

        Note

        If you already have suitable resources, such as a service account, cloud network, and subnet, you do not need to describe them again. Use their names and IDs in the appropriate parameters.

      For more information about the resources you can create with Terraform, see the provider documentation.

    2. 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.

      All the resources you need will then be created in the specified folder. You can check the new resources and their configuration using the management console.

      Each VM of the group will have а public IP address assigned. This way, you can easily connect to the group VM over SSH when checking the result.

      If you create an instance group without public IP addresses, you can still connect to a group VM over SSH by specifying its internal IP address or FQDN instead of the public IP address. However, you can only make such a connection from another virtual machine that has a public IP address and is located in the same Yandex Cloud cloud network as the group VM.

    Use the create REST API method for the InstanceGroup resource or the InstanceGroupService/Create gRPC API call.

Make sure the file storage is connected to VMs in the instance group. To do so, connect to a VM via SSH and navigate to the directory that you specified as the mount point.

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Creating a VM group connected to Object Storage