---
id: "openstack-blazar"
type: "component"
kind: "coordination-service"
provider: "openstack"
category: "ops"
aliases: "Resource Reservation service"
docs: "https://docs.openstack.org/blazar/latest/"
url: "https://localhost:3000/catalogue/components/openstack-blazar"
---

# OpenStack Blazar

Reservation service that leases virtual instances, physical hosts, floating IPs and flavor-based instances for a future time window.

| | |
|---|---|
| Provider | [openstack](https://localhost:3000/catalogue?provider=openstack) |
| Kind | [Coordination service](https://localhost:3000/catalogue/kinds/coordination-service) |
| Category | Operations |
| Official docs | [https://docs.openstack.org/blazar/latest/](https://docs.openstack.org/blazar/latest/) |
| Also known as | Resource Reservation service |

## Properties

| property | type | values | required | kind default | this component |
|---|---|---|---|---|---|
| `consensus` | enum | `none`, `raft`, `paxos`, `zab` | no | "none" | inherited |
| `leaseBased` | boolean | — | no | true | inherited |
| `managed` | boolean | — | no | false | **false** |
| `nodes` | integer | — | no | — | inherited |
| `replicated` | boolean | — | no | false | inherited |
| `reservationType` | enum | `virtual-instance`, `physical-host`, `floating-ip`, `flavor-instance` | no | — | inherited |
| `role` | enum | `metadata`, `lock`, `discovery`, `placement`, `sharding`, `leader-election`, `config` | yes | — | **"placement"** |

Bold values are the ones this component pins.

## Rules that apply · 2

### Shared dependency without redundancy `shared-dependency-without-redundancy` (error)

- Page: https://localhost:3000/catalogue/rules/shared-dependency-without-redundancy.md
- Why: The design requires redundant discovery, but this DNS or coordination service, which everything depends on, runs on a single provider or a single replica. Its failure is the whole system's failure.
- Applies to: every node of kind dns or coordination-service
- Message: Shared dependency '{{node.id}}' is not redundant, but the design requires redundant discovery.

It fires when:

- all of these hold:
  - the design requirement `availability.discoveryRedundant` is true
  - any of these hold:
    - the node's `redundantProviders` is false
    - the node's `replicated` is false

### Stateful engine pinned to a single zone `stateful-engine-pinned-to-single-zone` (error)

- Page: https://localhost:3000/catalogue/rules/stateful-engine-pinned-to-single-zone.md
- Why: A matching engine, coordination service or event store living in exactly one availability zone, with no failover and no replication, is lost with that zone. Everything that depends on it stops with it.
- Applies to: every node of kind matching-engine, coordination-service or event-store
- Message: '{{node.id}}' is pinned to a single availability zone with no failover or replication.

It fires when:

- all of these hold:
  - the node sits inside exactly 1 availability-zone group
  - any of these hold:
    - the node's `failover` is "none"
    - the node's `replicated` is false
    - the node's `replication` is "none"

## Other products of the same kind · 17

- [Microservices Engine](https://localhost:3000/catalogue/components/alibaba-mse.md) `alibaba-mse` — alibabacloud
- [AWS Cloud Map](https://localhost:3000/catalogue/components/aws-cloud-map.md) `aws-cloud-map` — aws
- [Azure Arc](https://localhost:3000/catalogue/components/azure-arc.md) `azure-arc` — azure
- [Azure Device Registry](https://localhost:3000/catalogue/components/azure-device-registry.md) `azure-device-registry` — azure
- [Durable Objects](https://localhost:3000/catalogue/components/cloudflare-durable-objects.md) `cloudflare-durable-objects` — cloudflare
- [Apache Helix](https://localhost:3000/catalogue/components/apache-helix.md) `apache-helix` — default
- [Consul](https://localhost:3000/catalogue/components/consul.md) `consul` — default
- [Generic coordination service](https://localhost:3000/catalogue/components/coordination-service.md) `coordination-service` — default
- [etcd](https://localhost:3000/catalogue/components/etcd.md) `etcd` — default
- [Eureka](https://localhost:3000/catalogue/components/eureka.md) `eureka` — default
- [Nacos](https://localhost:3000/catalogue/components/nacos.md) `nacos` — default
- [Oxia](https://localhost:3000/catalogue/components/oxia.md) `oxia` — default
- [Apache ZooKeeper](https://localhost:3000/catalogue/components/zookeeper.md) `zookeeper` — default
- [Service Directory](https://localhost:3000/catalogue/components/google-service-directory.md) `google-service-directory` — gcp
- [Endpoints](https://localhost:3000/catalogue/components/k8s-endpoints.md) `k8s-endpoints` — k8s
- [OpenStack Cyborg](https://localhost:3000/catalogue/components/openstack-cyborg.md) `openstack-cyborg` — openstack
- [OpenStack Placement](https://localhost:3000/catalogue/components/openstack-placement.md) `openstack-placement` — openstack

## Use it in a design

```yaml
nodes:
  - { id: "openstack-blazar", component: "openstack-blazar" }
```

## Source (`component` YAML, verbatim)

```yaml
# yaml-language-server: $schema=../../schema/component.schema.json
# OpenStack Blazar: resource reservation service. Per "Blazar, the OpenStack Reservation Service" users lease
# cloud capacity in advance - virtual instance, physical host, floating IP and flavor-based instance
# reservations - so Blazar decides where and when reserved resources are placed. It holds leases, not consensus
# state, so no replication or quorum behaviour is claimed.
schemaVersion: "1"
type: "component"
id: "openstack-blazar"
kind: "coordination-service"
provider: "openstack"
docs: "https://docs.openstack.org/blazar/latest/"
aliases: ["Resource Reservation service"]
defaults:
  role: "placement"
  managed: false
properties:
  reservationType:
    type: "enum"
    values: ["virtual-instance", "physical-host", "floating-ip", "flavor-instance"]
  leaseBased:
    type: "boolean"
    default: true
```

Human page: https://localhost:3000/catalogue/components/openstack-blazar