OAuth2.0 Client Credentials Grant Flow

Overview

OAuth2.0 Client Credentials Grant based on RFC6749 is implemented as an extension of Keystone. This extension uses the application credentials as its back-end because they have some similar features. Users can use application_credentials_id and application_credentials_secret as client credentials to obtain the OAuth2.0 access token. The access token can then be used to access the protected resources of the OpenStack API, which uses Keystone middleware supporting the OAuth2.0 Client Credentials Grant. See the Identity API reference for more information on generating OAuth2.0 access token.

Guide

Enable Keystone identity server to support OAuth2.0 Client Credentials Grant by the following steps in this guide. In this example, keystone.host is the domain name used by the Keystone identity server.

Enable Keystone HTTPS Service

The following part describes steps to enable both HTTP and HTTPS with a self-signed certificate.

Warning

According to RFC6749 , HTTPS must be enabled in the authorization server since requests include sensitive information, e.g., a client secret, in plain text. Note that you might have to enable both HTTP and HTTPS as some other OpenStack services or third-party applications don’t use OAuth2.0 and need HTTP for the authentication with the Keystone identity server.

  1. Generate an RSA private key.

stack@oauth2-0-server:/$ openssl genrsa -out keystone.key 2048
Generating RSA private key, 2048 bit long modulus (2 primes)
.........................................+++++
.........................+++++
e is 65537 (0x010001)

  1. Create a certificate signing request.

stack@oauth2-0-server:/$ openssl req -new -key keystone.key -out keystone.csr
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:keystone.host
Email Address []:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

  1. Generate a self-signed certificate.

stack@oauth2-0-server:/$ openssl x509 -req -days 365 -in keystone.csr \
-signkey keystone.key -out keystone.host.crt
Signature ok
subject=C = , ST = , L = , O = , OU = , CN = keystone.host, emailAddress =
Getting Private key

  1. Append the configuration file for setting the HTTPS port service under the directory /etc/apache2/sites-enabled/.

stack@oauth2-0-server:/$ sudo ln -s \
/etc/apache2/sites-available/000-default.conf \
/etc/apache2/sites-enabled/000-default.conf

  1. Modify the apache configuration file and add proxy rules to implement HTTPS support for the Keystone service.

stack@oauth2-0-server:/$ vi 000-default.conf
<VirtualHost *:443>
DocumentRoot /var/www/html
SSLCertificateFile /etc/ssl/certs/keystone.host.crt
SSLCertificateKeyFile /etc/ssl/certs/keystone.key
SSLEngine on
SSLProtocol  all -SSLv2 -SSLv3
SSLCipherSuite ECDH:AESGCM:HIGH:!RC4:!DH:!MD5:!aNULL:!eNULL
SSLHonorCipherOrder on
ProxyPass "/identity" "unix:/var/run/uwsgi/keystone-wsgi-public.socket|uwsgi://uwsgi-uds-keystone-wsgi-public" retry=0
</VirtualHost>

  1. Restart apache service so that the modified configuration information takes effect.

stack@oauth2-0-server:/$ systemctl restart apache2.service
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to restart 'apache2.service'.
Authenticating as: Ubuntu (ubuntu)
Password:
==== AUTHENTICATION COMPLETE ===

Enable application credentials authentication

Due to the design of the current implementation, the application credentials must be enabled in Keystone as it is used for the management of OAuth2.0 client credentials.

  1. Modify keystone.conf to support application credentials authentication.

stack@oauth2-0-server:/$ vi /etc/keystone/keystone.conf
[auth]
methods = external,password,token,application_credential

  1. Restart Keystone service so that the modified configuration information takes effect.

stack@oauth2-0-server:/$ sudo systemctl restart devstack@keystone.service

Try to access the Keystone APIs

At last, try to access the Keystone APIs to confirm that the server is working properly.

  1. Through the HTTP protocol, access the Keystone token API to confirm that the X-Auth-Token can be obtained normally.

stack@oauth2-0-server:/$ curl -si -X POST http://keystone.host/identity/v3/auth/tokens?nocatalog \
-d '{"auth":{"identity":{"methods":["password"],"password": {"user":{"domain":{"name":"Default"},"name":"username","password":"test_pwd"}}},"scope":{"project":{"domain":{"name":"Default"},"name":"admin"}}}}' \
-H 'Content-type:application/json'

HTTP/1.1 201 CREATED
Date: Mon, 28 Feb 2022 08:50:31 GMT
Server: Apache/2.4.41 (Ubuntu)
Content-Type: application/json
Content-Length: 648
X-Subject-Token: $x_auth_token
Vary: X-Auth-Token
x-openstack-request-id: req-e84d2387-10c7-4bb9-942e-61190e9186d9
Connection: close

{"token": {"methods": ["password"], "user": {"domain": {"id": "default", "name": "Default"}, "id": "eb98b8bbb2174aa5acd6cf57b0bf64c6", "name": "admin", "password_expires_at": null}, "audit_ids": ["RkU3ZQXuR7uKF2tEwgtkYg"], "expires_at": "2022-02-28T09:50:31.000000Z", "issued_at": "2022-02-28T08:50:31.000000Z", "project": {"domain": {"id": "default", "name": "Default"}, "id": "83808bea957a4ce1aa612aef63b24d1c", "name": "admin"}, "is_domain": false, "roles": [{"id": "c30201abb78848a6919f582d0cd74f84", "name": "admin"}, {"id": "459dcf48c6794731b700fc6aa1cad669", "name": "member"}, {"id": "54ee344bb009472c8223d4d76d9b1246", "name": "reader"}]}}

  1. Through the HTTPS protocol, access the Keystone token API to confirm that the X-Auth-Token can be obtained normally.

stack@oauth2-0-server:/$ curl -sik -X POST https://keystone.host/identity/v3/auth/tokens?nocatalog \
-d '{"auth":{"identity":{"methods":["password"],"password": {"user":{"domain":{"name":"Default"},"name":"username","password":"test_pwd"}}},"scope":{"project":{"domain":{"name":"Default"},"name":"admin"}}}}' \
-H 'Content-type:application/json'

HTTP/1.1 201 CREATED
Date: Tue, 01 Mar 2022 00:38:48 GMT
Server: Apache/2.4.41 (Ubuntu)
Content-Type: application/json
Content-Length: 648
X-Subject-Token: $x_auth_token
Vary: X-Auth-Token
x-openstack-request-id: req-324f20e2-16d6-4f26-aefc-e2913b76e36f
Connection: close

{"token": {"methods": ["password"], "user": {"domain": {"id": "default", "name": "Default"}, "id": "eb98b8bbb2174aa5acd6cf57b0bf64c6", "name": "admin", "password_expires_at": null}, "audit_ids": ["XFEM4-V4QQiA9v3JVLUeWw"], "expires_at": "2022-03-01T01:38:48.000000Z", "issued_at": "2022-03-01T00:38:48.000000Z", "project": {"domain": {"id": "default", "name": "Default"}, "id": "83808bea957a4ce1aa612aef63b24d1c", "name": "admin"}, "is_domain": false, "roles": [{"id": "c30201abb78848a6919f582d0cd74f84", "name": "admin"}, {"id": "459dcf48c6794731b700fc6aa1cad669", "name": "member"}, {"id": "54ee344bb009472c8223d4d76d9b1246", "name": "reader"}]}}

  1. Create OAuth2.0 client credentials through the application credentials API.

stack@oauth2-0-server:/$ curl -sik -X POST https://keystone.host/identity/v3/users/eb98b8bbb2174aa5acd6cf57b0bf64c6/application_credentials \
-H "X-Auth-Token: $x_auth_token" \
-H "Content-Type: application/json" \
-d '{"application_credential": {"name": "sample_001"}}'

HTTP/1.1 201 CREATED
Date: Tue, 01 Mar 2022 00:55:25 GMT
Server: Apache/2.4.41 (Ubuntu)
Content-Type: application/json
Content-Length: 890
Vary: X-Auth-Token
x-openstack-request-id: req-e73ffa83-78df-4663-bccc-dd3ac582417f
Connection: close

{"application_credential": {"id": "$oauth2_client_id", "name": "sample_001", "description": null, "user_id": "eb98b8bbb2174aa5acd6cf57b0bf64c6", "project_id": "83808bea957a4ce1aa612aef63b24d1c", "system": null, "expires_at": null, "unrestricted": null, "roles": [{"id": "c30201abb78848a6919f582d0cd74f84", "name": "admin", "domain_id": null, "description": null, "options": {"immutable": true}}, {"id": "459dcf48c6794731b700fc6aa1cad669", "name": "member", "domain_id": null, "description": null, "options": {"immutable": true}}, {"id": "54ee344bb009472c8223d4d76d9b1246", "name": "reader", "domain_id": null, "description": null, "options": {"immutable": true}}], "secret": "$auth2_client_secret", "links": {"self": "https://keystone.host/identity/v3/application_credentials/f96a2fec117141a6b5fbaa0485632244"}}}

  1. Obtain oauth2.0 access tokens through the “Basic” HTTP authentication with OAuth2.0 client credentials.

stack@oauth2-0-server:/$ curl -sik -u "$oauth2_client_id:$oauth2_client_secret" \
-X POST https://keystone.host/identity/v3/OS-OAUTH2/token
-H "application/x-www-form-urlencoded" -d "grant_type=client_credentials"
HTTP/1.1 200 OK
Date: Tue, 01 Mar 2022 00:56:59 GMT
Server: Apache/2.4.41 (Ubuntu)
Content-Type: application/json
Content-Length: 264
Vary: X-Auth-Token
x-openstack-request-id: req-a8358f51-2e0f-45a7-bb1e-7d29c6a793f4
Connection: close

{"access_token":"gAAAAABhi1cMynG89h8t6TJrxNiZuNzjcIUIxNctoVfuqTw7BpUedLKxjPymClVEnj9GhIT5u2mpjaJATlEAtaa3D6_t8jk_fV-mqo2IUlsmTPTnMwkcjh5FSHQVRdqvDxgY3nSqLA_Hfv-zPmjS5KWX3hmyDE5YWO1ztX6QNVQb4wTPyNL1-7I","expires_in":3600,"token_type":"Bearer"}