Compute API Reference

Overview

The OpenStack Compute API provides programmatic control over virtual machine instances, flavors, keypairs, availability zones, server groups, and hypervisor resources. The API follows RESTful conventions with JSON request and response bodies.

Prerequisites

A valid project-scoped token from the Identity API
Base URL: https://api.<your-domain>/compute/v2.1
Minimum API microversion: 2.1

API Versioning (Microversions)

The Compute API uses microversions to add new capabilities without breaking existing clients. Specify the desired microversion in the X-OpenStack-Nova-Microversion header:

Request with specific microversion

curl -X GET https://api.<your-domain>/compute/v2.1/servers \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "X-OpenStack-Nova-Microversion: 2.79"

Query supported microversions

curl -X GET https://api.<your-domain>/compute \
  -H "X-Auth-Token: $OS_TOKEN"

Key Endpoints

Resource	Method	Endpoint	Description
List instances	GET	`/servers`	List all instances in the project
Instance detail	GET	`/servers/detail`	List instances with full details
Get instance	GET	`/servers/{id}`	Get a specific instance
Create instance	POST	`/servers`	Launch a new instance
Delete instance	DELETE	`/servers/{id}`	Delete an instance
Instance action	POST	`/servers/{id}/action`	Perform an action (reboot, resize, etc.)
List flavors	GET	`/flavors/detail`	List all available instance sizes
List images	GET	`/images`	List available images
List keypairs	GET	`/os-keypairs`	List SSH keypairs
Create keypair	POST	`/os-keypairs`	Register or generate an SSH keypair
List AZs	GET	`/os-availability-zone`	List availability zones
Server groups	GET	`/os-server-groups`	List server groups (affinity/anti-affinity)
Hypervisors	GET	`/os-hypervisors/detail`	List hypervisors (admin)
Quotas	GET	`/os-quota-sets/{project_id}`	Show project compute quotas

Create an Instance

string

required

Display name for the instance.

string

required

Flavor ID or URL. Determines vCPU, RAM, and disk allocation.

string

required

Image ID or URL to boot from. Omit when booting from volume.

array

required

List of network objects. Each must include uuid (network ID) or port (port ID).

string

SSH keypair name to inject into the instance for key-based authentication.

array

List of security group name objects. Defaults to the default group.

string

Base64-encoded cloud-init user data script executed at first boot.

string

Target availability zone. Omit to let the scheduler choose.

curl -X POST https://api.<your-domain>/compute/v2.1/servers \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "server": {
      "name": "web-server-01",
      "flavorRef": "m1.medium",
      "imageRef": "ubuntu-22.04-amd64",
      "networks": [{ "uuid": "a1b2c3d4-e5f6-..." }],
      "key_name": "my-keypair",
      "security_groups": [{ "name": "web-servers" }]
    }
  }'

import requests

token = "your-token"
server = {
    "server": {
        "name": "web-server-01",
        "flavorRef": "m1.medium",
        "imageRef": "ubuntu-22.04-amd64",
        "networks": [{"uuid": "a1b2c3d4-e5f6-..."}],
        "key_name": "my-keypair",
        "security_groups": [{"name": "web-servers"}]
    }
}
resp = requests.post(
    "https://api.<your-domain>/compute/v2.1/servers",
    json=server,
    headers={"X-Auth-Token": token, "Content-Type": "application/json"}
)
print(resp.json()["server"]["id"])

{
  "server": {
    "id": "b1c2d3e4-f5a6-7890-b1c2-d3e4f5a67890",
    "name": "web-server-01",
    "status": "BUILD",
    "links": [
      { "href": "https://api.<your-domain>/compute/v2.1/servers/b1c2d3e4...", "rel": "self" }
    ],
    "adminPass": "auto-generated-password",
    "OS-DCF:diskConfig": "MANUAL"
  }
}

Instance Actions

Perform operations on a running instance via the /action endpoint:

Reboot
Stop / Start
Resize
Snapshot

Soft reboot (graceful OS restart)

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "reboot": { "type": "SOFT" } }'

Hard reboot (power cycle)

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "reboot": { "type": "HARD" } }'

Stop instance (power off)

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "os-stop": null }'

Start stopped instance

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "os-start": null }'

Resize to a larger flavor

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "resize": { "flavorRef": "m1.large" } }'

Confirm the resize

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "confirmResize": null }'

Create instance snapshot (image)

curl -X POST https://api.<your-domain>/compute/v2.1/servers/{id}/action \
  -H "X-Auth-Token: $OS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "createImage": { "name": "web-server-01-snapshot", "metadata": {} } }'

List Instances with Filtering

List all running instances

curl -X GET "https://api.<your-domain>/compute/v2.1/servers?status=ACTIVE" \
  -H "X-Auth-Token: $OS_TOKEN"

List instances with full details

curl -X GET https://api.<your-domain>/compute/v2.1/servers/detail \
  -H "X-Auth-Token: $OS_TOKEN"

List instances across all projects (admin)

curl -X GET "https://api.<your-domain>/compute/v2.1/servers/detail?all_tenants=1" \
  -H "X-Auth-Token: $OS_TOKEN"

Common filter parameters:

Parameter	Description
`status`	Filter by instance status: `ACTIVE`, `SHUTOFF`, `BUILD`, `ERROR`
`name`	Filter by instance name (supports regex)
`flavor`	Filter by flavor ID
`image`	Filter by image ID
`all_tenants`	`1` to list across all projects (admin only)
`limit`	Maximum number of results per page
`marker`	Pagination cursor — last instance ID from previous page

Error Reference

HTTP Status	Error Code	Description
`400`	`badRequest`	Invalid request body or parameter
`401`	`unauthorized`	Token missing, invalid, or expired
`403`	`forbidden`	Insufficient permissions for this operation
`404`	`itemNotFound`	Instance or resource not found
`409`	`conflictingRequest`	Operation not valid in current instance state
`413`	`entityTooLarge`	Request exceeds quota limits
`429`	`overLimit`	Rate limit exceeded

Next Steps

Storage API

Attach volumes and manage snapshots via the Storage API

Networking API

Create networks and assign floating IPs for your instances

Authentication

Manage tokens and application credentials

Core Services

Other Services

Overview

API Versioning (Microversions)

Key Endpoints

Create an Instance

Instance Actions

List Instances with Filtering

Error Reference

Next Steps

Storage API

Networking API

Authentication

​Overview

​API Versioning (Microversions)

​Key Endpoints

​Create an Instance

​Instance Actions

​List Instances with Filtering

​Error Reference

​Next Steps

Storage API

Networking API

Authentication

Overview

API Versioning (Microversions)

Key Endpoints

Create an Instance

Instance Actions

List Instances with Filtering

Error Reference

Next Steps