Create a fixed-size instance group

You can create a group with a fixed number of instances. The group size is set manually. For more information, see Manually scaled groups.

Warning

When creating a group, keep the limits in mind. Not to disrupt the component Instance Groups, do not update or delete manually created resources: target group Load Balancer, virtual machines and disks. To do this, update or delete the instance group.

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.

To create a fixed-size instance group:

Management console

CLI

API

In the management console, select the folder where you want to create an instance group.
Select Compute Cloud.
On the Virtual machines page, go to the Instance groups tab.
Click Create group.
In the Basic parameters section, enter:
- A group name in the Name field. The group name must be unique within the cloud.
  
  The name must be unique within the folder. The name may contain lowercase Latin letters, numbers, and hyphens. The first character must be a letter. The last character can't be a hyphen. The maximum length of the name is 63 characters.
- A group description in the Description field.
In the Allocation section, select availability zones. Cluster VMs may reside in different availability zones and regions. Learn more about the Cloud geography.
In the Instance template section, click Add:
- Select the required public image.
- In the Disks section:
  - Select the disk type (HDD or NVME).
  - Specify the disk size.
    
    To add more disks, click Add disk.
- In the Computing resources section:
  - Select the platform.
  - Specify the necessary number of vCPUs and amount of RAM.
- In the Network settings section:
  - Select the cloud network.
  - Specify if a public IP address is required.
- In the Access section, specify data required for accessing the VM:
  - Enter the username in the Login field.
  - In the SSH key field, paste the contents of the public key file.
    
    You need to create a key pair for SSH connection yourself. To generate keys, use third-party tools, such as ssh-keygen utilities on Linux and macOS or PuTTygen on Windows.
- Click Add.
In the Deployment section, specify:
- Expansion of group size for scaling up.
- Reduction of group size for scaling down.
- Maximum number of instances when creating a group.
- Maximum number of instances when deleting a group.
  
  For more information, see Deployment policy.
In the Scalability section:
- Select the scale type.
- Specify the required number of instances.
Click Create.

If you don't have the Yandex.Cloud command line interface yet, install 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 flag.

See the description of the CLI's create instance group command:
```
$ yc compute instance-group create --help
```
Check whether there are networks in the folder:
```
$ yc vpc network list
```
If there aren't any, create the necessary networks in VPC.

Select one of the public images (for example, CentOS 7).

To get a list of available images, run the following command:

$ yc compute image list --folder-id standard-images
+----------------------+-------------------------------------+--------------------------+----------------------+--------+
|          ID          |                NAME                 |          FAMILY          |     PRODUCT IDS      | STATUS |
+----------------------+-------------------------------------+--------------------------+----------------------+--------+
...
| fdvk34al8k5nltb58shr | centos-7-1549279494                 | centos-7                 | dqni65lfhvv2den5gtv9 | READY  |
| fdv7ooobjfl3ts9gqp0q | windows-2016-gvlk-1548913814        | windows-2016-gvlk        | dqnnc72gj2ist3ktjj1p | READY  |
| fdv4f5kv5cvf3ohu4flt | ubuntu-1604-lts-1549457823          | ubuntu-1604-lts          | dqnnb6dc7640c5i968ro | READY  |
...
+----------------------+-------------------------------------+--------------------------+----------------------+--------+

Create a YAML file with any name (for example, specification.yaml).

In the created file, indicate the following:

General information about the group:

name: first-fixed-group
service_account_id: <ID>
description: "This instance group was created from YAML config"

Keys:

Key	Value
`name`	A name for the instance group. The name must be unique within the folder. The name may contain lowercase Latin letters, numbers, and hyphens. The first character must be a letter. The last character can't be a hyphen. The maximum length of the name is 63 characters.
`service_account_id`	ID of the service account.
`description`	A description of the instance group.

Instance template:

instance_template:
    platform_id: standard-v1
    resources_spec:
        memory: 4g
        cores: 1
    boot_disk_spec:
        mode: READ_WRITE
        disk_spec:
            image_id: fdvk34al8k5nltb58shr
            type_id: network-hdd
            size: 32g
    network_interface_specs:
        - network_id: c64mknqgnd8avp6edhbt
          primary_v4_address_spec: {}

The disk size is specified in bytes by default. You can specify a different unit of measurement using the applicable suffix.

Name	Example of a YAML file entry:
Kilobyte	1073741824k
Megabyte	1048576m
Gigabyte	1024g
Terabyte	1t

Keys (the table contains the keys that directly define the instance parameters):

Key	Value
`platform_id`	Platform ID.
`memory`	Amount of memory (RAM).
`cores`	Number of processor cores (vCPUs).
`mode`	Disk access mode. - `READ_ONLY`: read-only access. - `READ_WRITE`: read/write access.
`image_id`	CentOS 7 public image ID.
`type_id`	Disk type.
`size`	Disk size.
`network_id`	The `default-net` ID.
`primary_v4_address_spec`	IPv4 specification. Only IPv4 is currently available. You can allow public access to group instances by specifying the IP version for the public IP address. For more information, see Template description in a YAML file.

The policies:

deploy_policy:
    max_unavailable: 1
    max_expansion: 0
scale_policy:
    fixed_scale:
        size: 3
allocation_policy:
    zones:
        - zone_id: ru-central1-a

Keys:

Key	Value
`deploy_policy`	Deployment policy for instances in the group.
`scale_policy`	Scaling policy for instances in the group.
`allocation_policy`	Policy for allocating instances across zones and regions.

Full code for the specification.yaml file:

name: first-fixed-group
service_account_id: ajed6ilf11qg839dcl1e
description: "This instance group was created from YAML config"
instance_template:
    platform_id: standard-v1
    resources_spec:
        memory: 4g
        cores: 1
    boot_disk_spec:
        mode: READ_WRITE
        disk_spec:
            image_id: fdvk34al8k5nltb58shr
            type_id: network-hdd
            size: 32g
    network_interface_specs:
        - network_id: c64mknqgnd8avp6edhbt
          primary_v4_address_spec: {}
deploy_policy:
    max_unavailable: 1
    max_expansion: 0
scale_policy:
    fixed_scale:
        size: 3
allocation_policy:
    zones:
        - zone_id: ru-central1-a

Create an instance group in the default folder:
```
$ yc compute instance-group create --file specification.yaml
```
This command creates a group of three similar instances with the following characteristics:
- Named first-fixed-group.
- Running CentOS 7.
- In the default-net network.
- In the ru-central1-a availability zone.
- With a single core and 4 GB RAM.
- With a 32 GB network HDD.

Use the create API method.