Configuring Services to work with Keystone

Once Keystone is installed and running (see Configuring Keystone), services need to be configured to work with it. To do this, we primarily install and configure middleware for the OpenStack service to handle authentication tasks or otherwise interact with Keystone.

In general:

  • Clients making calls to the service will pass in an authentication token.
  • The Keystone middleware will look for and validate that token, taking the appropriate action.
  • It will also retrieve additional information from the token such as user name, id, tenant name, id, roles, etc...

The middleware will pass those data down to the service as headers. More details on the architecture of that setup is described in Middleware Architecture

Setting up credentials

Admin Token

For a default installation of Keystone, before you can use the REST API, you need to define an authorization token. This is configured in keystone.conf file under the section [DEFAULT]. In the sample file provided with the Keystone project, the line defining this token is:

[DEFAULT]
admin_token = ADMIN

A “shared secret” that can be used to bootstrap Keystone. This token does not represent a user, and carries no explicit authorization. To disable in production (highly recommended), remove AdminTokenAuthMiddleware from your paste application pipelines (for example, in keystone-paste.ini)

Setting up tenants, users, and roles

You need to minimally define a tenant, user, and role to link the tenant and user as the most basic set of details to get other services authenticating and authorizing with Keystone.

You will also want to create service users for nova, glance, swift, etc. to be able to use to authenticate users against Keystone. The auth_token middleware supports using either the shared secret described above as admin_token or users for each service.

See Configuring Keystone for a walk through on how to create tenants, users, and roles.

Setting up services

Creating Service Users

To configure the OpenStack services with service users, we need to create a tenant for all the services, and then users for each of the services. We then assign those service users an Admin role on the service tenant. This allows them to validate tokens - and authenticate and authorize other user requests.

Create a tenant for the services, typically named ‘service’ (however, the name can be whatever you choose):

keystone tenant-create --name=service

This returns a UUID of the tenant - keep that, you’ll need it when creating the users and specifying the roles.

Create service users for nova, glance, swift, and neutron (or whatever subset is relevant to your deployment):

keystone user-create --name=nova \
                     --pass=Sekr3tPass \
                     --tenant_id=[the uuid of the tenant] \
                     --email=nova@nothing.com

Repeat this for each service you want to enable. Email is a required field in keystone right now, but not used in relation to the service accounts. Each of these commands will also return a UUID of the user. Keep those to assign the Admin role.

For adding the Admin role to the service accounts, you’ll need to know the UUID of the role you want to add. If you don’t have them handy, you can look it up quickly with:

keystone role-list

Once you have it, assign the service users to the Admin role. This is all assuming that you’ve already created the basic roles and settings as described in Configuring Keystone:

keystone user-role-add –tenant_id=[uuid of the service tenant]
–user=[uuid of the service account] –role=[uuid of the Admin role]

Defining Services

Keystone also acts as a service catalog to let other OpenStack systems know where relevant API endpoints exist for OpenStack Services. The OpenStack Dashboard, in particular, uses this heavily - and this must be configured for the OpenStack Dashboard to properly function.

The endpoints for these services are defined in a template, an example of which is in the project as the file etc/default_catalog.templates.

Keystone supports two means of defining the services, one is the catalog template, as described above - in which case everything is detailed in that template.

The other is a SQL backend for the catalog service, in which case after Keystone is online, you need to add the services to the catalog:

keystone service-create --name=nova \
                               --type=compute \
                               --description="Nova Compute Service"
keystone service-create --name=ec2 \
                               --type=ec2 \
                               --description="EC2 Compatibility Layer"
keystone service-create --name=glance \
                               --type=image \
                               --description="Glance Image Service"
keystone service-create --name=keystone \
                               --type=identity \
                               --description="Keystone Identity Service"
keystone service-create --name=swift \
                               --type=object-store \
                               --description="Swift Service"

Setting Up Middleware

Keystone Auth-Token Middleware

The Keystone auth_token middleware is a WSGI component that can be inserted in the WSGI pipeline to handle authenticating tokens with Keystone. You can get more details of the middleware in Middleware Architecture.

Configuring Nova to use Keystone

When configuring Nova, it is important to create an admin service token for the service (from the Configuration step above) and include that as the key ‘admin_token’ in Nova’s api-paste.ini [filter:authtoken] section or in nova.conf [keystone_authtoken] section.

Configuring Swift to use Keystone

Similar to Nova, Swift can be configured to use Keystone for authentication rather than its built in ‘tempauth’. Refer to the overview_auth documentation in Swift.

Auth-Token Middleware with Username and Password

It is also possible to configure Keystone’s auth_token middleware using the ‘admin_user’ and ‘admin_password’ options. When using the ‘admin_user’ and ‘admin_password’ options the ‘admin_token’ parameter is optional. If ‘admin_token’ is specified it will be used only if the specified token is still valid.

Here is an example paste config filter that makes use of the ‘admin_user’ and ‘admin_password’ parameters:

[filter:authtoken]
paste.filter_factory = keystoneclient.middleware.auth_token:filter_factory
auth_port = 35357
auth_host = 127.0.0.1
auth_token = 012345SECRET99TOKEN012345
admin_user = admin
admin_password = keystone123

It should be noted that when using this option an admin tenant/role relationship is required. The admin user is granted access to the ‘Admin’ role to the ‘admin’ tenant.

The auth_token middleware can also be configured in nova.conf [keystone_authtoken] section to keep paste config clean of site-specific parameters:

[filter:authtoken]
paste.filter_factory = keystoneclient.middleware.auth_token:filter_factory

and in nova.conf:

[DEFAULT]
...
auth_strategy=keystone

[keystone_authtoken]
auth_port = 35357
auth_host = 127.0.0.1
admin_user = admin
admin_password = keystone123