Creating an instance group with a Container Optimized Image

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To run multiple instances of the service in Docker containers, you can create an instance group from a Container Optimized Image. In such groups, you can update Docker containers with VM metadata using the COI or Docker Compose specification.

Alert

When creating instance groups, keep the limits in mind. Not to disrupt the component Instance Groups, do not update or delete manually created resources: target group Network Load Balancer, VMs, and disks. Instead of this, change or delete the entire 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 an instance group based on a Container Optimized Image:

If you don't 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.
View a description of the CLI command to create an instance group:
CLI
```
yc compute instance-group create --help
```
Check whether there are networks in the folder:
CLI
```
yc vpc network list
```
If there aren't any, create one.
Create a YAML file with a name like specification.yaml.
Find out the ID of the latest version of the public Container Optimized Image.

The Container Optimized Image in the Yandex Container Registry can be updated and changed according to releases. This will not automatically update the VM image to the latest version. To create an instance group with the latest Container Optimized Image version, you need to check whether it's available yourself:
CLI

Marketplace
```
yc compute image get-latest-from-family container-optimized-image --folder-id standard-images
```
Result:
```
id: <ID of latest COI version>
folder_id: standard-images
...
```
1. Go to the page Cloud Marketplace and select the image with the desired configuration:
  - Container Optimized Image.
  - Container Optimized Image GPU.
2. Under Product IDs, copy the value of image_id.

In the specification.yaml file you created, specify the following:

General information about the group:
```
name: container-optimized-group
service_account_id: aje3932acd8avp6edhbt
description: "This instance group was created from YAML config."
```
Where:
- name: An arbitrary name of 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: Service account ID.
- description: A description of the instance group.

Instance template:

instance_template:
  platform_id: standard-v3
  resources_spec:
    memory: 2G
    cores: 2
  boot_disk_spec:
    mode: READ_WRITE
    disk_spec:
      image_id: <ID of latest COI version>
      type_id: network-hdd
      size: 32G
  network_interface_specs:
    - network_id: c64mknqgnd8avp6edhbt
      primary_v4_address_spec: {}
  metadata:
    docker-container-declaration: |-
      spec:
        containers:
          - name: nginx
            image: cr.yandex/mirror/nginx:1.17.4-alpine
            securityContext:
              privileged: false
            tty: false
            stdin: false

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

Suffix	Prefix and multiplier	Example
`k`	kilo- (2¹⁰)	`640k` = 640 × 2¹⁰ = `655360`
`m`	mega- (2²⁰)	`48m` = 48 × 2²⁰ = `50331648`
`g`	giga- (2³⁰)	`10g` = 10 × 2³⁰ = `10737418240`
`t`	tera- (2⁴⁰)	`4t` = 4 × 2⁴⁰ = `4398046511104`
`p`	peta- (2⁵⁰)	`2p` = 2 × 2⁵⁰ = `2251799813685248`

Where:

platform_id: Platform ID.
memory: Amount of RAM.
cores: Number of processor cores (vCPUs).
mode: Disk access mode:
- READ_ONLY: Read-only access.
- READ_WRITE: Read/write access.
image_id: ID of the public Container Optimized Image.
type_id: Disk type.
size: Disk size.
network_id: ID of default-net.
primary_v4_address_spec: IPv4 specification. Only IPv4 is currently available. You can grant public access to the group's instances by specifying the IP version for a public IP address.
metadata: Values to pass to the VM metadata.
docker-container-declaration: Key in the VM metadata that is used with the COI specification of the Docker container. In the metadata, you can use the Docker Compose specification. To do this, specify the docker-compose key instead of the docker-container-declaration key.

Policies:

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

Where:

deploy_policy: Deployment policy for instances in the group.
scale_policy: Scaling policy for instances in the group.
allocation_policy: Allocation policy of the instances by zone and region.

Full code for the specification.yaml file:

name: container-optimized-group
service_account_id: aje3932acd8avp6edhbt
description: "This instance group was created from YAML config."
instance_template:
  service_account_id: aje3932acd8avp6edhbt # ID of the service account to access private Docker images.
  platform_id: standard-v3
  resources_spec:
    memory: 2G
    cores: 2
  boot_disk_spec:
    mode: READ_WRITE
    disk_spec:
      image_id: <ID of latest COI version>
      type_id: network-hdd
      size: 32G
  network_interface_specs:
    - network_id: c64mknqgnd8avp6edhbt
      primary_v4_address_spec: {}
  metadata:
    docker-container-declaration: |-
      spec:
        containers:
          - name: nginx
            image: cr.yandex/mirror/nginx:1.17.4-alpine
            securityContext:
              privileged: false
            tty: false
            stdin: false
deploy_policy:
  max_unavailable: 1
  max_expansion: 0
scale_policy:
  fixed_scale:
    size: 3
allocation_policy:
  zones:
    - zone_id: ru-central1-a

Note

To use in specification.yaml the Docker Compose specification, specify the docker-compose key instead of the docker-container-declaration key.

Create an instance group in the default folder:
CLI
```
yc compute instance-group create --file specification.yaml
```
This command creates a group of three similar instances with the following characteristics:
- Named container-optimized-group.
- From the latest version of the public Container Optimized Image.
- With a running Docker container based on cr.yandex/mirror/nginx:1.17.4-alpine.
- In the default-net network.
- In the ru-central1-a availability zone.
- With 2 vCPUs and 2 GB of RAM.
- With a 32 GB network HDD.

Creating an instance group with a Container Optimized Image

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