OpenStack Identity (Keystone)
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Configuring Keystone

man/keystone-manage man/keystone-all

Once Keystone is installed, it is configured via a primary configuration file (etc/keystone.conf), a PasteDeploy configuration file (etc/keystone-paste.ini), possibly a separate logging configuration file, and initializing data into Keystone using the command line client.

By default, Keystone starts a service on IANA-assigned port 35357. This may overlap with your system's ephemeral port range, so another process may already be using this port without being explicitly configured to do so. To prevent this scenario from occurring, it's recommended that you explicitly exclude port 35357 from the available ephemeral port range. On a Linux system, this would be accomplished by:

$ sysctl -w ''

To make the above change persistent, net.ipv4.ip_local_reserved_ports = 35357 should be added to /etc/sysctl.conf or to /etc/sysctl.d/keystone.conf.

Starting and Stopping Keystone

Start Keystone services using the command:

$ keystone-all

Invoking this command starts up two wsgi.Server instances, admin (the administration API) and main (the primary/public API interface). Both services are configured to run in a single process.

Stop the process using Control-C.


If you have not already configured Keystone, it may not start as expected.

Configuration Files

The Keystone configuration files are an ini file format based on Paste, a common system used to configure Python WSGI based applications. The PasteDeploy configuration entries (WSGI pipeline definitions) can be provided in a separate keystone-paste.ini file, while general and driver-specific configuration parameters are in the primary configuration file keystone.conf. The primary configuration file is organized into the following sections:

  • [DEFAULT] - General configuration
  • [assignment] - Assignment system driver configuration
  • [auth] - Authentication plugin configuration
  • [cache] - Caching layer configuration
  • [catalog] - Service catalog driver configuration
  • [credential] - Credential system driver configuration
  • [ec2] - Amazon EC2 authentication driver configuration
  • [endpoint_filter] - Endpoint filtering extension configuration
  • [endpoint_policy] - Endpoint policy extension configuration
  • [federation] - Federation driver configuration
  • [identity] - Identity system driver configuration
  • [identity_mapping] - Identity mapping system driver configuration
  • [kvs] - KVS storage backend configuration
  • [ldap] - LDAP configuration options
  • [memcache] - Memcache configuration options
  • [oauth1] - OAuth 1.0a system driver configuration
  • [os_inherit] - Inherited role assignment extension
  • [paste_deploy] - Pointer to the PasteDeploy configuration file
  • [policy] - Policy system driver configuration for RBAC
  • [revoke] - Revocation system driver configuration
  • [saml] - SAML configuration options
  • [signing] - Cryptographic signatures for PKI based tokens
  • [ssl] - SSL configuration
  • [stats] - Stats system driver configuration
  • [token] - Token driver & token provider configuration
  • [trust] - Trust extension configuration

The Keystone primary configuration file is expected to be named keystone.conf. When starting Keystone, you can specify a different configuration file to use with --config-file. If you do not specify a configuration file, Keystone will look in the following directories for a configuration file, in order:

  • ~/.keystone/
  • ~/
  • /etc/keystone/
  • /etc/

PasteDeploy configuration file is specified by the config_file parameter in [paste_deploy] section of the primary configuration file. If the parameter is not an absolute path, then Keystone looks for it in the same directories as above. If not specified, WSGI pipeline definitions are loaded from the primary configuration file.

Domain-specific Drivers


This functionality is new in Juno.

Keystone supports the option (disabled by default) to specify identity driver configurations on a domain by domain basis, allowing, for example, a specific domain to have its own LDAP or SQL server. This is configured by specifying the following options:

domain_specific_drivers_enabled = True
domain_config_dir = /etc/keystone/domains

Setting domain_specific_drivers_enabled to True will enable this feature, causing Keystone to look in the domain_config_dir for config files of the form:


Options given in the domain specific configuration file will override those in the primary configuration file for the specified domain only. Domains without a specific configuration file will continue to use the options from the primary configuration file.


Keystone does not support moving the contents of a domain (i.e. "it's" users and groups) from one backend to another, nor group membership across backend boundaries.


Although Keystone supports multiple LDAP backends via domain specific configuration files, it currently only supports one SQL backend. This could be either the default driver or a single domain-specific backend, perhaps for storing service users in a predominantly LDAP installation.

Due to the need for user and group IDs to be unique across an OpenStack installation and for Keystone to be able to deduce which domain and backend to use from just a user or group ID, it dynamically builds a persistent identity mapping table from a public ID to the actual domain, local ID (within that backend) and entity type. The public ID is automatically generated by Keystone when it first encounters the entity. If the local ID of the entity is from a backend that does not guarantee to generate UUIDs, a hash algorithm will generate a public ID for that entity, which is what will be exposed by Keystone.

The use of a hash will ensure that if the public ID needs to be regenerated then the same public ID will be created. This is useful if you are running multiple keystones and want to ensure the same ID would be generated whichever server you hit.

While Keystone will dynamically maintain the identity mapping, including removing entries when entities are deleted via the Keystone, for those entities in backends that are managed outside of Keystone (e.g. a Read Only LDAP), Keystone will not know if entities have been deleted and hence will continue to carry stale identity mappings in its table. While benign, keystone provides an ability for operators to purge the mapping table of such stale entries using the keystone-manage command, for example:

$ keystone-manage mapping_purge --domain-name DOMAINA --local-id

A typical usage would be for an operator to obtain a list of those entries in an external backend that had been deleted out-of-band to Keystone, and then call keystone-manage to purge those entries by specifying the domain and local-id. The type of the entity (i.e. user or group) may also be specified if this is needed to uniquely identify the mapping.

Since public IDs are be regeneratable with the correct generator implementation, then, if the details of those entries that have been deleted are not available, then it is safe to simply bulk purge identity mappings periodically, for example:

$ keystone-manage mapping_purge --domain-name DOMAINA

will purge all the mappings for DOMAINA. The entire mapping table can be purged with the following command:

$ keystone-manage mapping_purge --all

Public ID Generators

Keystone supports a customizable public ID generator and it is specified in the [identity_mapping] section of the configuration file. Keystone provides a sha256 generator as default, which produces regeneratable public IDs. The generator algorithm for public IDs is a balance between key size (i.e. the length of the public ID), the probability of collision and, in some circumstances, the security of the public ID. The maximum length of public ID supported by Keystone is 64 characters, and the default generator (sha256) uses this full capability. Since the public ID is what is exposed externally by Keystone and potentially stored in external systems, some installations may wish to make use of other generator algorithms that have a different trade-off of attributes. A different generator can be installed by configuring the following property:

  • generator - identity mapping generator. Defaults to keystone.identity.generators.sha256.Generator


Changing the generator may cause all existing public IDs to be become invalid, so typically the generator selection should be considered immutable for a given installation.

Authentication Plugins


This feature is only supported by Keystone for the Identity API v3 clients.

Keystone supports authentication plugins and they are specified in the [auth] section of the configuration file. However, an authentication plugin may also have its own section in the configuration file. It is up to the plugin to register its own configuration options.

  • methods - comma-delimited list of authentication plugin names
  • <plugin name> - specify the class which handles to authentication method, in the same manner as one would specify a backend driver.

Keystone provides three authentication methods by default. password handles password authentication and token handles token authentication. external is used in conjunction with authentication performed by a container web server that sets the REMOTE_USER environment variable. For more details, refer to External Authentication <external-auth>.

How to Implement an Authentication Plugin

All authentication plugins must extend the keystone.auth.core.AuthMethodHandler class and implement the authenticate() method. The authenticate() method expects the following parameters.

  • context - Keystone's request context
  • auth_payload - the content of the authentication for a given method
  • auth_context - user authentication context, a dictionary shared by all plugins. It contains method_names and extras by default. method_names is a list and extras is a dictionary.

If successful, the authenticate() method must provide a valid user_id in auth_context and return None. method_name is used to convey any additional authentication methods in case authentication is for re-scoping. For example, if the authentication is for re-scoping, a plugin must append the previous method names into method_names. Also, a plugin may add any additional information into extras. Anything in extras will be conveyed in the token's extras field.

If authentication requires multiple steps, the authenticate() method must return the payload in the form of a dictionary for the next authentication step.

If authentication is unsuccessful, the authenticate() method must raise a keystone.exception.Unauthorized exception.

Simply add the new plugin name to the methods list along with your plugin class configuration in the [auth] sections of the configuration file to deploy it.

If the plugin require addition configurations, it may register its own section in the configuration file.

Plugins are invoked in the order in which they are specified in the methods attribute of the authentication request body. If multiple plugins are invoked, all plugins must succeed in order to for the entire authentication to be successful. Furthermore, all the plugins invoked must agree on the user_id in the auth_context.

The REMOTE_USER environment variable is only set from a containing webserver. However, to ensure that a user must go through other authentication mechanisms, even if this variable is set, remove external from the list of plugins specified in methods. This effectively disables external authentication. For more details, refer to ExternalAuthentication <external-auth>.

Token Persistence Driver

Keystone supports customizable token persistence drivers. These can be specified in the [token] section of the configuration file. Keystone provides three non-test persistence backends. These can be set with the [token]\driver configuration option.

The drivers Keystone provides are:

  • keystone.token.persistence.backends.memcache_pool.Token - The pooled memcached token persistence engine. This backend supports the concept of pooled memcache client object (allowing for the re-use of the client objects). This backend has a number of extra tunable options in the [memcache] section of the config.
  • keystone.token.persistence.backends.sql.Token - The SQL-based (default) token persistence engine.
  • keystone.token.persistence.backends.memcache.Token - The memcached based token persistence backend. This backend relies on dogpile.cache and stores the token data in a set of memcached servers. The servers URLs are specified in the [memcache]\servers configuration option in the Keystone config.


It is recommended you use the keystone.token.persistence.backend.memcache_pool.Token backend instead of keystone.token.persistence.backend.memcache.Token as the token persistence driver if you are deploying Keystone under eventlet instead of Apache + mod_wsgi. This recommendation is due to known issues with the use of thread.local under eventlet that can allow the leaking of memcache client objects and consumption of extra sockets.

Token Provider

Keystone supports customizable token provider and it is specified in the [token] section of the configuration file. Keystone provides both UUID and PKI token providers. However, users may register their own token provider by configuring the following property.

  • provider - token provider driver. Defaults to keystone.token.providers.uuid.Provider

Note that token_format in the [signing] section is deprecated but still being supported for backward compatibility. Therefore, if provider is set to keystone.token.providers.pki.Provider, token_format must be PKI. Conversely, if provider is keystone.token.providers.uuid.Provider, token_format must be UUID.

For a customized provider, token_format must not set to PKI or UUID.


UUID-based tokens are randomly generated opaque strings that are issued and validated by the identity service. They must be persisted by the identity service in order to be later validated, and revoking them is simply a matter of deleting them from the token persistence backend.

PKI-based tokens are Cryptographic Message Syntax (CMS) strings that can be verified offline using keystone's public signing key. The only reason for them to be persisted by the identity service is to later build token revocation lists (explicit lists of tokens that have been revoked), otherwise they are theoretically ephemeral. PKI tokens should therefore have much better scaling characteristics (decentralized validation). They are base-64 encoded (and are therefore not URL-friendly without encoding) and may be too long to fit in either headers or URLs if they contain extensive service catalogs or other additional attributes.


Both UUID and PKI-based tokens are bearer tokens, meaning that they must be protected from unnecessary disclosure to prevent unauthorized access.

The current architectural approaches for both UUID and PKI-based tokens have pain points exposed by environments under heavy load (search bugs and blueprints for the latest details and potential solutions).

Caching Layer

Keystone supports a caching layer that is above the configurable subsystems (e.g. token, identity, etc). Keystone uses the dogpile.cache library which allows for flexible cache backends. The majority of the caching configuration options are set in the [cache] section. However, each section that has the capability to be cached usually has a caching boolean value that will toggle caching for that specific section. The current default behavior is that subsystem caching is enabled, but the global toggle is set to disabled.

[cache] configuration section:

  • enabled - enables/disables caching across all of keystone

  • debug_cache_backend - enables more in-depth logging from the cache backend (get, set, delete, etc)

  • backend - the caching backend module to use e.g. dogpile.cache.memcached


    A given backend must be registered with dogpile.cache before it can be used. The default backend is the Keystone no-op backend (keystone.common.cache.noop). If caching is desired a different backend will need to be specified. Current functional backends are:

    • dogpile.cache.memcached - Memcached backend using the standard python-memcached library
    • dogpile.cache.pylibmc - Memcached backend using the pylibmc library
    • dogpile.cache.bmemcached - Memcached using python-binary-memcached library.
    • dogpile.cache.redis - Redis backend
    • dogpile.cache.dbm - local DBM file backend
    • dogpile.cache.memory - in-memory cache
    • keystone.cache.mongo - MongoDB as caching backend
    • keystone.cache.memcache_pool - An eventlet safe implementation of dogpile.cache.memcached.

      This implementation also provides client connection re-use.


      dogpile.cache.memory is not suitable for use outside of unit testing as it does not cleanup it's internal cache on cache expiration, does not provide isolation to the cached data (values in the store can be inadvertently changed without extra layers of data protection added), and does not share cache between processes. This means that caching and cache invalidation will not be consistent or reliable when using Keystone and the dogpile.cache.memory backend under any real workload.


      Do not use dogpile.cache.memcached backend if you are deploying Keystone under eventlet. There are known issues with the use of thread.local under eventlet that can allow the leaking of memcache client objects and consumption of extra sockets.

  • expiration_time - int, the default length of time to cache a specific value. A value of 0

    indicates to not cache anything. It is recommended that the enabled option be used to disable cache instead of setting this to 0.

  • backend_argument - an argument passed to the backend when instantiated

    backend_argument should be specified once per argument to be passed to the back end and in the format of <argument name>:<argument value>. e.g.: backend_argument = host:localhost

  • proxies - comma delimited list of ProxyBackends e.g. my.example.Proxy, my.example.Proxy2

Current Keystone systems that have caching capabilities:
  • token

    The token system has a separate cache_time configuration option, that can be set to a value above or below the global expiration_time default, allowing for different caching behavior from the other systems in Keystone. This option is set in the [token] section of the configuration file.

    The Token Revocation List cache time is handled by the configuration option revocation_cache_time in the [token] section. The revocation list is refreshed whenever a token is revoked. It typically sees significantly more requests than specific token retrievals or token validation calls.

  • assignment

    The assignment system has a separate cache_time configuration option, that can be set to a value above or below the global expiration_time default, allowing for different caching behavior from the other systems in Keystone. This option is set in the [assignment] section of the configuration file.

    Currently assignment has caching for project, domain, and role specific requests (primarily around the CRUD actions). Caching is currently not implemented on grants. The list (list_projects, list_domains, etc) methods are not subject to caching.


    Be aware that if a read-only assignment backend is in use, the cache will not immediately reflect changes on the back end. Any given change may take up to the cache_time (if set in the [assignment] section of the configuration) or the global expiration_time (set in the [cache] section of the configuration) before it is reflected. If this type of delay (when using a read-only assignment backend) is an issue, it is recommended that caching be disabled on assignment. To disable caching specifically on assignment, in the [assignment] section of the configuration set caching to False.

For more information about the different backends (and configuration options):

Certificates for PKI

PKI stands for Public Key Infrastructure. Tokens are documents, cryptographically signed using the X509 standard. In order to work correctly token generation requires a public/private key pair. The public key must be signed in an X509 certificate, and the certificate used to sign it must be available as Certificate Authority (CA) certificate. These files can be generated either using the keystone-manage utility, or externally generated.

keystone-manage pki_setup is a development tool. We recommend that you do not use keystone-manage pki_setup in a production environment. In production, an external CA should be used instead. This is because the CA secret key should generally be kept apart from the token signing secret keys so that a compromise of a node does not lead to an attacker being able to generate valid signed Keystone tokens. This is a low probability attack vector, as compromise of a Keystone service machine's filesystem security almost certainly means the attacker will be able to gain direct access to the token backend.

The files need to be in the locations specified by the top level Keystone configuration file as specified in the above section. Additionally, the private key should only be readable by the system user that will run Keystone. The values that specify where to read the certificates are under the [signing] section of the configuration file. The configuration values are:

  • token_format - Determines the algorithm used to generate tokens. Can be either UUID or PKI. Defaults to PKI. This option must be used in conjunction with provider configuration in the [token] section.
  • certfile - Location of certificate used to verify tokens. Default is /etc/keystone/ssl/certs/signing_cert.pem
  • keyfile - Location of private key used to sign tokens. Default is /etc/keystone/ssl/private/signing_key.pem
  • ca_certs - Location of certificate for the authority that issued the above certificate. Default is /etc/keystone/ssl/certs/ca.pem
  • ca_key - Default is /etc/keystone/ssl/private/cakey.pem
  • key_size - Default is 2048
  • valid_days - Default is 3650

Signing Certificate Issued by External CA

You may use a signing certificate issued by an external CA instead of generated by keystone-manage. However, certificate issued by external CA must satisfy the following conditions:

  • all certificate and key files must be in Privacy Enhanced Mail (PEM) format
  • private key files must not be protected by a password

When using signing certificate issued by an external CA, you do not need to specify key_size, valid_days and ca_key as they will be ignored.

The basic workflow for using a signing certificate issued by an external CA involves:

  1. Request Signing Certificate from External CA
  2. Convert certificate and private key to PEM if needed
  3. Install External Signing Certificate

Request Signing Certificate from External CA

One way to request a signing certificate from an external CA is to first generate a PKCS #10 Certificate Request Syntax (CRS) using OpenSSL CLI.

First create a certificate request configuration file (e.g. cert_req.conf):

[ req ]
default_bits            = 2048
default_keyfile         = keystonekey.pem
default_md              = default

prompt                  = no
distinguished_name      = distinguished_name

[ distinguished_name ]
countryName             = US
stateOrProvinceName     = CA
localityName            = Sunnyvale
organizationName        = OpenStack
organizationalUnitName  = Keystone
commonName              = Keystone Signing
emailAddress            =

Then generate a CRS with OpenSSL CLI. Do not encrypt the generated private key. Must use the -nodes option.

For example:

$ openssl req -newkey rsa:2048 -keyout signing_key.pem -keyform PEM -out signing_cert_req.pem -outform PEM -config cert_req.conf -nodes

If everything is successfully, you should end up with signing_cert_req.pem and signing_key.pem. Send signing_cert_req.pem to your CA to request a token signing certificate and make sure to ask the certificate to be in PEM format. Also, make sure your trusted CA certificate chain is also in PEM format.

Install External Signing Certificate

Assuming you have the following already:

  • signing_cert.pem - (Keystone token) signing certificate in PEM format
  • signing_key.pem - corresponding (non-encrypted) private key in PEM format
  • cacert.pem - trust CA certificate chain in PEM format

Copy the above to your certificate directory. For example:

$ mkdir -p /etc/keystone/ssl/certs
$ cp signing_cert.pem /etc/keystone/ssl/certs/
$ cp signing_key.pem /etc/keystone/ssl/certs/
$ cp cacert.pem /etc/keystone/ssl/certs/
$ chmod -R 700 /etc/keystone/ssl/certs

Make sure the certificate directory is root-protected.

If your certificate directory path is different from the default /etc/keystone/ssl/certs, make sure it is reflected in the [signing] section of the configuration file.

Service Catalog

Keystone provides two configuration options for your service catalog.

SQL-based Service Catalog (sql.Catalog)

A dynamic database-backed driver fully supporting persistent configuration.

keystone.conf example:

driver = keystone.catalog.backends.sql.Catalog


A template_file does not need to be defined for the sql.Catalog driver.

To build your service catalog using this driver, see the built-in help:

$ keystone
$ keystone help service-create
$ keystone help endpoint-create

You can also refer to an example in Keystone (tools/

File-based Service Catalog (templated.Catalog)

The templated catalog is an in-memory backend initialized from a read-only template_file. Choose this option only if you know that your service catalog will not change very much over time.


Attempting to manage your service catalog using keystoneclient commands (e.g. keystone endpoint-create) against this driver will result in HTTP 501 Not Implemented errors. This is the expected behavior. If you want to use these commands, you must instead use the SQL-based Service Catalog driver.

keystone.conf example:

driver = keystone.catalog.backends.templated.Catalog
template_file = /opt/stack/keystone/etc/default_catalog.templates

The value of template_file is expected to be an absolute path to your service catalog configuration. An example template_file is included in Keystone, however you should create your own to reflect your deployment.

Another such example is available in devstack (files/default_catalog.templates).


Logging is configured externally to the rest of Keystone. Configure the path to your logging configuration file using the [DEFAULT] log_config option of keystone.conf. If you wish to route all your logging through syslog, set the [DEFAULT] use_syslog option.

A sample log_config file is included with the project at etc/logging.conf.sample. Like other OpenStack projects, Keystone uses the Python logging module, which includes extensive configuration options for choosing the output levels and formats.


Keystone provides some basic request/response monitoring statistics out of the box.

Enable data collection by defining a stats_monitoring filter and including it at the beginning of any desired WSGI pipelines:

paste.filter_factory = keystone.contrib.stats:StatsMiddleware.factory

pipeline = stats_monitoring [...] public_service

Enable the reporting of collected data by defining a stats_reporting filter and including it near the end of your admin_api WSGI pipeline (After *_body middleware and before *_extension filters is recommended):

paste.filter_factory = keystone.contrib.stats:StatsExtension.factory

pipeline = [...] json_body stats_reporting ec2_extension [...] admin_service

Query the admin API for statistics using:

$ curl -H 'X-Auth-Token: ADMIN' http://localhost:35357/v2.0/OS-STATS/stats

Reset collected data using:

$ curl -H 'X-Auth-Token: ADMIN' -X DELETE http://localhost:35357/v2.0/OS-STATS/stats


Keystone may be configured to support SSL and 2-way SSL out-of-the-box. The X509 certificates used by Keystone can be generated by keystone-manage or obtained externally and configured for use with Keystone as described in this section. Here is the description of each of them and their purpose:

Types of certificates

  • cacert.pem: Certificate Authority chain to validate against.
  • ssl_cert.pem: Public certificate for Keystone server.
  • middleware.pem: Public and private certificate for Keystone middleware/client.
  • cakey.pem: Private key for the CA.
  • ssl_key.pem: Private key for the Keystone server.

Note that you may choose whatever names you want for these certificates, or combine the public/private keys in the same file if you wish. These certificates are just provided as an example.


To enable SSL modify the etc/keystone.conf file accordingly under the [ssl] section. SSL configuration example using the included sample certificates:

enable = True
certfile = <path to keystone.pem>
keyfile = <path to keystonekey.pem>
ca_certs = <path to ca.pem>
ca_key = <path to cakey.pem>
cert_required = False
  • enable: True enables SSL. Defaults to False.
  • certfile: Path to Keystone public certificate file.
  • keyfile: Path to Keystone private certificate file. If the private key is included in the certfile, the keyfile maybe omitted.
  • ca_certs: Path to CA trust chain.
  • cert_required: Requires client certificate. Defaults to False.

When generating SSL certificates the following values are read

  • key_size: Key size to create. Defaults to 1024.
  • valid_days: How long the certificate is valid for. Defaults to 3650 (10 years).
  • ca_key: The private key for the CA. Defaults to /etc/keystone/ssl/certs/cakey.pem.
  • cert_subject: The subject to set in the certificate. Defaults to /C=US/ST=Unset/L=Unset/O=Unset/CN=localhost. When setting the subject it is important to set CN to be the address of the server so client validation will succeed. This generally means having the subject be at least /CN=<keystone ip>

Generating SSL certificates

Certificates for secure HTTP communication can be generated by:

$ keystone-manage ssl_setup

This will create a private key, a public key and a certificate that will be used to encrypt communications with keystone. In the event that a Certificate Authority is not given a testing one will be created.

It is likely in a production environment that these certificates will be created and provided externally. Note that ssl_setup is a development tool and is only recommended for developments environment. We do not recommend using ssl_setup for production environments.


Keystone provides a user CRUD filter that can be added to the public_api pipeline. This user crud filter allows users to use a HTTP PATCH to change their own password. To enable this extension you should define a user_crud_extension filter, insert it after the *_body middleware and before the public_service app in the public_api WSGI pipeline in keystone-paste.ini e.g.:

paste.filter_factory = keystone.contrib.user_crud:CrudExtension.factory

pipeline = stats_monitoring url_normalize token_auth admin_token_auth xml_body json_body debug ec2_extension user_crud_extension public_service

Each user can then change their own password with a HTTP PATCH :

$ curl -X PATCH http://localhost:5000/v2.0/OS-KSCRUD/users/<userid> -H "Content-type: application/json"  \
-H "X_Auth_Token: <authtokenid>" -d '{"user": {"password": "ABCD", "original_password": "DCBA"}}'

In addition to changing their password all of the users current tokens will be deleted (if the backend used is SQL)

Inherited Role Assignment Extension

Keystone provides an optional extension that adds the capability to assign roles to a domain that, rather than affect the domain itself, are instead inherited to all projects owned by that domain. This extension is disabled by default, but can be enabled by including the following in keystone.conf:

enabled = True

Token Binding

Token binding refers to the practice of embedding information from external authentication providers (like a company's Kerberos server) inside the token such that a client may enforce that the token only be used in conjunction with that specified authentication. This is an additional security mechanism as it means that if a token is stolen it will not be usable without also providing the external authentication.

To activate token binding you must specify the types of authentication that token binding should be used for in keystone.conf e.g.:

bind = kerberos

Currently only kerberos is supported.

To enforce checking of token binding the enforce_token_bind parameter should be set to one of the following modes:

  • disabled disable token bind checking

  • permissive enable bind checking, if a token is bound to a mechanism that is unknown to the server then ignore it. This is the default.

  • strict enable bind checking, if a token is bound to a mechanism that is unknown to the server then this token should be rejected.

  • required enable bind checking and require that at least 1 bind mechanism is used for tokens.

  • named enable bind checking and require that the specified authentication mechanism is used. e.g.:

    enforce_token_bind = kerberos

    Do not set enforce_token_bind = named as there is not an authentication mechanism called named.

Limiting the number of entities returned in a collection

Keystone provides a method of setting a limit to the number of entities returned in a collection, which is useful to prevent overly long response times for list queries that have not specified a sufficiently narrow filter. This limit can be set globally by setting list_limit in the default section of keystone.conf, with no limit set by default. Individual driver sections may override this global value with a specific limit, for example:

list_limit = 100

If a response to list_{entity} call has been truncated, then the response status code will still be 200 (OK), but the truncated attribute in the collection will be set to true.

Sample Configuration Files

The etc/ folder distributed with Keystone contains example configuration files for each Server application.

  • etc/keystone.conf.sample
  • etc/keystone-paste.ini
  • etc/logging.conf.sample
  • etc/default_catalog.templates

Keystone API protection with Role Based Access Control (RBAC)

Like most OpenStack projects, Keystone supports the protection of its APIs by defining policy rules based on an RBAC approach. These are stored in a JSON policy file, the name and location of which is set in the main Keystone configuration file.

Each Keystone v3 API has a line in the policy file which dictates what level of protection is applied to it, where each line is of the form:

<api name>: <rule statement> or <match statement>


<rule statement> can contain <rule statement> or <match statement>

<match statement> is a set of identifiers that must match between the token provided by the caller of the API and the parameters or target entities of the API call in question. For example:

"identity:create_user": [["role:admin", "domain_id:%(user.domain_id)s"]]

Indicates that to create a user you must have the admin role in your token and in addition the domain_id in your token (which implies this must be a domain scoped token) must match the domain_id in the user object you are trying to create. In other words, you must have the admin role on the domain in which you are creating the user, and the token you are using must be scoped to that domain.

Each component of a match statement is of the form:

<attribute from token>:<constant> or <attribute related to API call>

The following attributes are available

  • Attributes from token: user_id, the domain_id or project_id depending on the scope, and the list of roles you have within that scope

  • Attributes related to API call: Any parameters that are passed into the API call are available, along with any filters specified in the query string. Attributes of objects passed can be referenced using an object.attribute syntax (e.g. user.domain_id). The target objects of an API are also available using a target.object.attribute syntax. For instance:

    "identity:delete_user": [["role:admin", "domain_id:%(target.user.domain_id)s"]]

    would ensure that the user object that is being deleted is in the same domain as the token provided.

Every target object has an id and a name available as target.<object>.id and target.<object>.name. Other attributes are retrieved from the database and vary between object types. Moreover, some database fields are filtered out (e.g. user passwords).

List of object attributes:

  • role:
  • user:
    • target.user.default_project_id
    • target.user.description
    • target.user.domain_id
    • target.user.enabled
  • group:
  • domain:
    • target.domain.enabled
  • project:
    • target.project.description
    • target.project.domain_id
    • target.project.enabled

The default policy.json file supplied provides a somewhat basic example of API protection, and does not assume any particular use of domains. For multi-domain configuration installations where, for example, a cloud provider wishes to allow administration of the contents of a domain to be delegated, it is recommended that the supplied policy.v3cloudsample.json is used as a basis for creating a suitable production policy file. This example policy file also shows the use of an admin_domain to allow a cloud provider to enable cloud administrators to have wider access across the APIs.

A clean installation would need to perhaps start with the standard policy file, to allow creation of the admin_domain with the first users within it. The domain_id of the admin domain would then be obtained and could be pasted into a modified version of policy.v3cloudsample.json which could then be enabled as the main policy file.

Preparing your deployment

Step 1: Configure keystone.conf

Ensure that your keystone.conf is configured to use a SQL driver:

driver = keystone.identity.backends.sql.Identity

You may also want to configure your [sql] settings to better reflect your environment:

connection = sqlite:///keystone.db
idle_timeout = 200


It is important that the database that you specify be different from the one containing your existing install.

Step 2: Sync your new, empty database

You should now be ready to initialize your new database without error, using:

$ keystone-manage db_sync

To test this, you should now be able to start keystone-all and use the Keystone Client to list your tenants (which should successfully return an empty list from your new database):

$ keystone --os-token ADMIN --os-endpoint tenant-list
| id | name | enabled |


We're providing the default OS_SERVICE_TOKEN and OS_SERVICE_ENDPOINT values from keystone.conf to connect to the Keystone service. If you changed those values, or deployed Keystone to a different endpoint, you will need to change the provided command accordingly.

Initializing Keystone

keystone-manage is designed to execute commands that cannot be administered through the normal REST API. At the moment, the following calls are supported:

  • db_sync: Sync the database.
  • db_version: Print the current migration version of the database.
  • mapping_purge: Purge the identity mapping table.
  • pki_setup: Initialize the certificates used to sign tokens.
  • saml_idp_metadata: Generate identity provider metadata.
  • ssl_setup: Generate certificates for SSL.
  • token_flush: Purge expired tokens

Invoking keystone-manage by itself will give you additional usage information.

The private key used for token signing can only be read by its owner. This prevents unauthorized users from spuriously signing tokens. keystone-manage pki_setup Should be run as the same system user that will be running the Keystone service to ensure proper ownership for the private key file and the associated certificates.

Adding Users, Tenants, and Roles with python-keystoneclient

Users, tenants, and roles must be administered using admin credentials. There are two ways to configure python-keystoneclient to use admin credentials, using the either an existing token or password credentials.

Authenticating with a Token


If your Keystone deployment is brand new, you will need to use this authentication method, along with your [DEFAULT] admin_token.

To use Keystone with a token, set the following flags:

  • --os-endpoint OS_SERVICE_ENDPOINT: allows you to specify the Keystone endpoint to communicate with. The default endpoint is http://localhost:35357/v2.0
  • --os-token OS_SERVICE_TOKEN: your service token

To administer a Keystone endpoint, your token should be either belong to a user with the admin role, or, if you haven't created one yet, should be equal to the value defined by [DEFAULT] admin_token in your keystone.conf.

You can also set these variables in your environment so that they do not need to be passed as arguments each time:

$ export OS_SERVICE_ENDPOINT=http://localhost:35357/v2.0

Authenticating with a Password

To administer a Keystone endpoint, the following user referenced below should be granted the admin role.

  • --os_username OS_USERNAME: Name of your user
  • --os_password OS_PASSWORD: Password for your user
  • --os_tenant_name OS_TENANT_NAME: Name of your tenant
  • --os_auth_url OS_AUTH_URL: URL of your Keystone auth server, e.g. http://localhost:35357/v2.0

You can also set these variables in your environment so that they do not need to be passed as arguments each time:

$ export OS_USERNAME=my_username
$ export OS_PASSWORD=my_password
$ export OS_TENANT_NAME=my_tenant

Example usage

keystone is set up to expect commands in the general form of keystone command argument, followed by flag-like keyword arguments to provide additional (often optional) information. For example, the command user-list and tenant-create can be invoked as follows:

# Using token auth env variables
$ export OS_SERVICE_TOKEN=secrete_token
$ keystone user-list
$ keystone tenant-create --name=demo

# Using token auth flags
$ keystone --os-token=secrete --os-endpoint= user-list
$ keystone --os-token=secrete --os-endpoint= tenant-create --name=demo

# Using user + password + tenant_name env variables
$ export OS_USERNAME=admin
$ export OS_PASSWORD=secrete
$ export OS_TENANT_NAME=admin
$ keystone user-list
$ keystone tenant-create --name=demo

# Using user + password + tenant_name flags
$ keystone --os_username=admin --os_password=secrete --os_tenant_name=admin user-list
$ keystone --os_username=admin --os_password=secrete --os_tenant_name=admin tenant-create --name=demo

For additional examples refer to CLI Examples.

Removing Expired Tokens

In the SQL backend expired tokens are not automatically removed. These tokens can be removed with:

$ keystone-manage token_flush

The memcache backend automatically discards expired tokens and so flushing is unnecessary and if attempted will fail with a NotImplemented error.

Configuring the LDAP Identity Provider

As an alternative to the SQL Database backing store, Keystone can use a directory server to provide the Identity service. An example Schema for OpenStack would look like this:

dn: dc=openstack,dc=org
dc: openstack
objectClass: dcObject
objectClass: organizationalUnit
ou: openstack

dn: ou=Projects,dc=openstack,dc=org
objectClass: top
objectClass: organizationalUnit
ou: groups

dn: ou=Users,dc=openstack,dc=org
objectClass: top
objectClass: organizationalUnit
ou: users

dn: ou=Roles,dc=openstack,dc=org
objectClass: top
objectClass: organizationalUnit
ou: roles

The corresponding entries in the Keystone configuration file are:

url = ldap://localhost
user = dc=Manager,dc=openstack,dc=org
password = badpassword
suffix = dc=openstack,dc=org
use_dumb_member = False
allow_subtree_delete = False

user_tree_dn = ou=Users,dc=openstack,dc=org
user_objectclass = inetOrgPerson

project_tree_dn = ou=Projects,dc=openstack,dc=org
project_objectclass = groupOfNames

role_tree_dn = ou=Roles,dc=openstack,dc=org
role_objectclass = organizationalRole

The default object classes and attributes are intentionally simplistic. They reflect the common standard objects according to the LDAP RFCs. However, in a live deployment, the correct attributes can be overridden to support a preexisting, more complex schema. For example, in the user object, the objectClass posixAccount from RFC2307 is very common. If this is the underlying objectclass, then the uid field should probably be uidNumber and username field either uid or cn. To change these two fields, the corresponding entries in the Keystone configuration file are:

user_id_attribute = uidNumber
user_name_attribute = cn

There is a set of allowed actions per object type that you can modify depending on your specific deployment. For example, the users are managed by another tool and you have only read access, in such case the configuration is:

user_allow_create = False
user_allow_update = False
user_allow_delete = False

project_allow_create = True
project_allow_update = True
project_allow_delete = True

role_allow_create = True
role_allow_update = True
role_allow_delete = True

There are some configuration options for filtering users, tenants and roles, if the backend is providing too much output, in such case the configuration will look like:

user_filter = (memberof=CN=openstack-users,OU=workgroups,DC=openstack,DC=org)
project_filter =
role_filter =

In case that the directory server does not have an attribute enabled of type boolean for the user, there is several configuration parameters that can be used to extract the value from an integer attribute like in Active Directory:

user_enabled_attribute = userAccountControl
user_enabled_mask      = 2
user_enabled_default   = 512

In this case the attribute is an integer and the enabled attribute is listed in bit 1, so the if the mask configured user_enabled_mask is different from 0, it gets the value from the field user_enabled_attribute and it makes an ADD operation with the value indicated on user_enabled_mask and if the value matches the mask then the account is disabled.

It also saves the value without mask to the user identity in the attribute enabled_nomask. This is needed in order to set it back in case that we need to change it to enable/disable a user because it contains more information than the status like password expiration. Last setting user_enabled_mask is needed in order to create a default value on the integer attribute (512 = NORMAL ACCOUNT on AD)

In case of Active Directory the classes and attributes could not match the specified classes in the LDAP module so you can configure them like:

user_objectclass          = person
user_id_attribute         = cn
user_name_attribute       = cn
user_mail_attribute       = mail
user_enabled_attribute    = userAccountControl
user_enabled_mask         = 2
user_enabled_default      = 512
user_attribute_ignore     = tenant_id,tenants
project_objectclass       = groupOfNames
project_id_attribute      = cn
project_member_attribute  = member
project_name_attribute    = ou
project_desc_attribute    = description
project_enabled_attribute = extensionName
project_attribute_ignore  =
role_objectclass          = organizationalRole
role_id_attribute         = cn
role_name_attribute       = ou
role_member_attribute     = roleOccupant
role_attribute_ignore     =

Debugging LDAP

For additional information on LDAP connections, performance (such as slow response time), or field mappings, setting debug_level in the [ldap] section is used to enable debugging:

debug_level = 4095

This setting in turn sets OPT_DEBUG_LEVEL in the underlying python library. This field is a bit mask (integer), and the possible flags are documented in the OpenLDAP manpages. Commonly used values include 255 and 4095, with 4095 being more verbose.


Enabling debug_level will negatively impact performance.

Enabled Emulation

Some directory servers do not provide any enabled attribute. For these servers, the user_enabled_emulation and project_enabled_emulation attributes have been created. They are enabled by setting their respective flags to True. Then the attributes user_enabled_emulation_dn and project_enabled_emulation_dn may be set to specify how the enabled users and projects (tenants) are selected. These attributes work by using a groupOfNames and adding whichever users or projects (tenants) that you want enabled to the respective group. For example, this will mark any user who is a member of enabled_users as enabled:

user_enabled_emulation = True
user_enabled_emulation_dn = cn=enabled_users,cn=groups,dc=openstack,dc=org

The default values for user and project (tenant) enabled emulation DN is cn=enabled_users,$user_tree_dn and cn=enabled_tenants,$project_tree_dn respectively.

Secure Connection

If you are using a directory server to provide the Identity service, it is strongly recommended that you utilize a secure connection from Keystone to the directory server. In addition to supporting ldaps, Keystone also provides Transport Layer Security (TLS) support. There are some basic configuration options for enabling TLS, identifying a single file or directory that contains certificates for all the Certificate Authorities that the Keystone LDAP client will recognize, and declaring what checks the client should perform on server certificates. This functionality can easily be configured as follows:

use_tls = True
tls_cacertfile = /etc/keystone/ssl/certs/cacert.pem
tls_cacertdir = /etc/keystone/ssl/certs/
tls_req_cert = demand

A few points worth mentioning regarding the above options. If both tls_cacertfile and tls_cacertdir are set then tls_cacertfile will be used and tls_cacertdir is ignored. Furthermore, valid options for tls_req_cert are demand, never, and allow. These correspond to the standard options permitted by the TLS_REQCERT TLS option.

Read Only LDAP

Many environments typically have user and group information in directories that are accessible by LDAP. This information is for read-only use in a wide array of applications. Prior to the Havana release, we could not deploy Keystone with read-only directories as backends because Keystone also needed to store information such as projects, roles, domains and role assignments into the directories in conjunction with reading user and group information.

Keystone now provides an option whereby these read-only directories can be easily integrated as it now enables its identity entities (which comprises users, groups, and group memberships) to be served out of directories while assignments (which comprises projects, roles, role assignments, and domains) are to be served from a different Keystone backend (i.e. SQL). To enable this option, you must have the following keystone.conf options set:

driver = keystone.identity.backends.ldap.Identity

driver = keystone.assignment.backends.sql.Assignment

With the above configuration, Keystone will only lookup identity related information such users, groups, and group membership from the directory, while assignment related information will be provided by the SQL backend. Also note that if there is an LDAP Identity, and no assignment backend is specified, the assignment backend will default to LDAP. Although this may seem counterintuitive, it is provided for backwards compatibility. Nonetheless, the explicit option will always override the implicit option, so specifying the options as shown above will always be correct. Finally, it is also worth noting that whether or not the LDAP accessible directory is to be considered read only is still configured as described in a previous section above by setting values such as the following in the [ldap] configuration section:

user_allow_create = False
user_allow_update = False
user_allow_delete = False

Connection Pooling

Various LDAP backends in Keystone use a common LDAP module to interact with LDAP data. By default, a new connection is established for LDAP operations. This can become highly expensive when TLS support is enabled which is a likely configuraton in enterprise setup. Re-using of connectors from a connection pool drastically reduces overhead of initiating a new connection for every LDAP operation.

Keystone now provides connection pool support via configuration. This change will keep LDAP connectors alive and re-use for subsequent LDAP operations. A connection lifespan is going to be configurable with other pooling specific attributes. The change is made in LDAP handler layer logic which is primarily responsible for LDAP connection and shared common operations.

In LDAP identity driver, Keystone authenticates end user by LDAP bind with user DN and provided password. These kind of auth binds can fill up the pool pretty quickly so a separate pool is provided for those end user auth bind calls. If a deployment does not want to use pool for those binds, then it can disable pooling selectively by use_auth_pool as false. If a deployment wants to use pool for those auth binds, then use_auth_pool needs to be true. For auth pool, a different pool size (auth_pool_size) and connection lifetime (auth_pool_connection_lifetime) can be specified. With enabled auth pool, its connection lifetime should be kept short so that pool frequently re-binds the connection with provided creds and works reliably in end user password change case. When use_pool is false (disabled), then auth pool configuration is also not used.

Connection pool configuration is added in [ldap] configuration section:

# Enable LDAP connection pooling. (boolean value)

# Connection pool size. (integer value)

# Maximum count of reconnect trials. (integer value)

# Time span in seconds to wait between two reconnect trials.
# (floating point value)

# Connector timeout in seconds. Value -1 indicates indefinite wait for
# response. (integer value)

# Connection lifetime in seconds.  (integer value)

# Enable LDAP connection pooling for end user authentication. If use_pool
# is disabled, then this setting is meaningless and is not used at all.
# (boolean value)

# End user auth connection pool size. (integer value)

# End user auth connection lifetime in seconds. (integer value)