API endpoint configuration recommendations

Internal API communications

OpenStack provides both public facing and private API endpoints. By default, OpenStack components use the publicly defined endpoints. The recommendation is to configure these components to use the API endpoint within the proper security domain.

Services select their respective API endpoints based on the OpenStack service catalog. These services might not obey the listed public or internal API end point values. This can lead to internal management traffic being routed to external API endpoints.

Configure internal URLs in the Identity service catalog

The Identity service catalog should be aware of your internal URLs. While this feature is not utilized by default, it may be leveraged through configuration. Additionally, it should be forward-compatible with expectant changes once this behavior becomes the default.

To register an internal URL for an endpoint:

$ openstack endpoint create identity \
  --region RegionOne internal \

Replace MANAGEMENT_IP with the management IP address of your controller node.

Configure applications for internal URLs

You can force some services to use specific API endpoints. Therefore, it is recommended that each OpenStack service communicating to the API of another service must be explicitly configured to access the proper internal API endpoint.

Each project may present an inconsistent way of defining target API endpoints. Future releases of OpenStack seek to resolve these inconsistencies through consistent use of the Identity service catalog.

Configuration example #1: nova


Configuration example #2: cinder

glance_host = 'https://glance-server'

Paste and middleware

Most API endpoints and other HTTP services in OpenStack use the Python Paste Deploy library. From a security perspective, this library enables manipulation of the request filter pipeline through the application’s configuration. Each element in this chain is referred to as middleware. Changing the order of filters in the pipeline or adding additional middleware might have unpredictable security impact.

Commonly, implementers add middleware to extend OpenStack’s base functionality. We recommend implementers make careful consideration of the potential exposure introduced by the addition of non-standard software components to their HTTP request pipeline.

For more information about Paste Deploy, see Python Paste Deployment documentation.

API endpoint process isolation and policy

You should isolate API endpoint processes, especially those that reside within the public security domain should be isolated as much as possible. Where deployments allow, API endpoints should be deployed on separate hosts for increased isolation.


Many operating systems now provide compartmentalization support. Linux supports namespaces to assign processes into independent domains. Other parts of this guide cover system compartmentalization in more detail.

Network policy

Because API endpoints typically bridge multiple security domains, you must pay particular attention to the compartmentalization of the API processes. See Bridging security domains for additional information in this area.

With careful modeling, you can use network ACLs and IDS technologies to enforce explicit point to point communication between network services. As a critical cross domain service, this type of explicit enforcement works well for OpenStack’s message queue service.

To enforce policies, you can configure services, host-based firewalls (such as iptables), local policy (SELinux or AppArmor), and optionally global network policy.

Mandatory access controls

You should isolate API endpoint processes from each other and other processes on a machine. The configuration for those processes should be restricted to those processes not only by Discretionary Access Controls, but through Mandatory Access Controls. The goal of these enhanced access controls is to aid in the containment and escalation of API endpoint security breaches. With mandatory access controls, such breaches severely limit access to resources and provide earlier alerting on such events.

API endpoint rate-limiting

Rate Limiting is a means to control the frequency of events received by a network based application. When robust rate limiting is not present, it can result in an application being susceptible to various denial of service attacks. This is especially true for APIs, which by their nature are designed to accept a high frequency of similar request types and operations.

Within OpenStack, it is recommended that all endpoints, especially public, are provided with an extra layer of protection, by means of either a rate-limiting proxy or web application firewall.

It is key that the operator carefully plans and considers the individual performance needs of users and services within their OpenStack cloud when configuring and implementing any rate limiting functionality.

Common solutions for providing rate-limiting are Nginx, HAProxy, OpenRepose, or Apache Modules such as mod_ratelimit, mod_qos, or mod_security.