r8 - 2021-08-20 - 13:44:05 - ShubjitNaikYou are here: TWiki >  Deployment Web > DeploymentInstallingUpgradingAndMigrating > JazzAuthorizationServer > ELMAndOAuth20ServerToServer

ELM and OAuth 2.0 Server to Server communication via Client Credentials Grant uc.png

Authors: ShubjitNaik
Build basis: Engineering Lifecycle Management 7.x

When deployed with Jazz Authorization Server (IBM Liberty OIDC feature) Engineering Lifecycle Management solution supports OAuth 2.0. Refer the article ELM and OAuth 2.0 to understand how to use OAuth 2.0 protocol flow with ELM deployed with Jazz Authorization Server. The article focuses on the context of a user login and then perform an action on behalf of that user.

In some cases, applications may need an access token to act on behalf of themselves rather than a user, which is more of server-to-server communication. The Client Credentials grant is used when applications request an access token to access their own resources, not on behalf of a user. In this case, the client can request an access token using only its client credentials.

The focus of this article is on using the Client Credentials Grant OAuth flow with ELM.

OAuth 2.0 - A Quick Intro

OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf.

Access tokens are credentials used to access protected resources. An access token is a string representing an authorization issued to the client. The string is usually opaque to the client. Tokens represent specific scopes and durations of access, granted by the resource owner, and enforced by the resource server and authorization server.

An authorization grant is a credential representing the resource owner's authorization (to access its protected resources) used by the client to obtain an access token. This specification defines four grant types and for further details on the grant types review the OAuth 2.0 Framework at OAuth 2.0 . In this article we will focus on the Client Credentials Grant Type

In the next section we will showcase how to register a new client to Jazz Authorization Server and access ELM Protected resources via the Client Credentials grant type.

Accessing ELM Protected Resources via Client Credentials Grant Type

The Client Credentials grant type is used by clients to obtain an access token outside of the context of a user.

High Level Authorization Flow

Considering ELM deployed with Jazz Authorization Server, the Access flow is as following

  • Pre-Req - Register a new Client with Jazz Authorization Server
    • A functional user to associate with a request made on behalf of a client, who has the required access and license assigned
  • Request for Access Token with Client credentials
  • Access ELM Protected Resources via Access Token

Register Client with Jazz Authorization Server

Before using OAuth with your application, you must register your application with Jazz Authorization Server. During registration you would need to provide Application Name, Scope, Redirect URI or Callback URL and Grant types. In this example, we are using a Script to list out EWM/ERM project areas and are using CURL commands. We will register a client with JAS mentioning ClientID, ClientSecret and other details as follows

# cd <JAS_HOME>/cli
# ./mkclient -a https://jas.example.com/oidc/endpoint/jazzop \
-P client_name="<CLIENTNAME>" \
-P client_id="<CLIENT_ID>"  -P client_secret="<CLIENT_SECRET>" \
-P redirect_uris="https://<application_URL>/auth/sso","https://<redirect_uri2>/" \
-P trusted_uri_prefixes="https://<Trusted_application_URL>/" \
-P functional_user_id=<Functional User> \
-P functional_user_groupIds="JazzAdmins" \
-P scope="openid profile email general" \
-P preauthorized_scope="openid profile email general" \
-P response_types="code","token" \
-P grant_types="password","authorization_code","client_credentials","refresh_token" \
-P introspect_tokens=true

In the above example replace the following variables

  • jas.example.com - The URL to your Jazz Authorization Server
  • JAS_ADMIN and PASSWORD - Jazz Authorization Server Administrator User and password
  • CLIENTNAME - Name to uniquely identify your Client
  • CLIENT_ID and CLIENT_SECRET (You can create your own)
  • Redirect URI Application Redirect URIs
  • Trusted URI - Trusted URIs of Application acessing Jazz Authorization Server
  • FUNCTIONAL USER - The user ID to associate with a request made on behalf of a client in a client_credentials grant type (Create a user, grant access to projects and assign licenses)
  • DONOT change values for scope, preauthorized_scope, response types and grant types

Here is an example command for registering a clientId to be used with CURL commands
# ./mkclient -a https://jas.example.com/oidc/endpoint/jazzop -u JazzUser:JazzPassword \
-P client_name="CURL Client" -P client_id="curlclientId" -P client_secret="curlclientpassword" \
-P functional_user_id=curl_user \
-P functional_user_groupIds="JazzAdmins" \
-P redirect_uris="https://jas.example.com/jazzop","https://localhost/jazzop" \
-P trusted_uri_prefixes="https://jas.example.com/","https://localhost/" \
-P scope="openid profile email general" -P preauthorized_scope="openid profile email general" \
-P response_types="code","token"  \
-P grant_types="password","authorization_code","client_credentials","refresh_token" \
-P introspect_tokens=true

  • You can review the registration details via the URL https://jas.example.com/oidc/endpoint/jazzop/registration

Request for Access Token with Client credentials

In this example, we are using a Script (bash) to list out EWM/ETM/ERM project areas and are using CURL commands. Once the Client is registered with Jazz Authorization server, we can create a POST request to the Token endpoint URL providing the Client Credentials (ClientID and ClientSecret) using CURL as follows:

curl -k --location --request POST \
'https://jas.example.com/oidc/endpoint/jazzop/token' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'grant_type=client_credentials' \
--data-urlencode 'client_id=curlclientId' \
--data-urlencode 'client_secret=curlclientpassword' \
--data-urlencode 'scope=openid profile email general'

  • jas.example.com is your Jazz Authorization server
  • client_Id, client_secret are the values created earlier while registering the client

If the client credentials are valid, JAS will send a response containing the Access token which is valid for 2 hours by default. A sample response is shown below:

{"access_token":"nwc5fn9tDtqC2RDlTaG41ygNdAppOTvE2Trw1X4E","token_type":"Bearer","expires_in":7200,"scope":"general openid profile email"}

Capture the value "access_token":"nwc5fn9tDtqC2RDlTaG41ygNdAppOTvE2Trw1X4E"

Access ELM Resources with the Access Token

Now that we have an access token using Client Credentials grant, we can access ELM APIs using this Access Token as a Header on a GET request. Here is a GET request with CURL to list ERM Project Areas, replace the Bearer value with the Access Token.

curl -k --location --request GET 'https://elm.example.com/rm/process/project-areas' \
--header 'Authorization: Bearer nwc5fn9tDtqC2RDlTaG41ygNdAppOTvE2Trw1X4E' 

Sample result of the command:

<?xml version="1.0" encoding="UTF-8"?><jp06:project-areas xmlns:jp06="http://jazz.net/xmlns/prod/jazz/process/0.6/">
    <jp06:project-area jp06:name="Money That Matters RM">
        <jp06:summary>Money That Matters RM</jp06:summary>
        <jp06:description>The purpose of this project is to specify and manage the requirements of the JKE Business Recovery Matters project.</jp06:description>
        <jp:admins-url xmlns:jp="http://jazz.net/xmlns/prod/jazz/process/1.0/">https://elm.example.com/rm/process/project-areas/_F5xhQD-_EeuV6NBd2WfUvQ/admins</jp:admins-url>
        <jp:timelines-url xmlns:jp="http://jazz.net/xmlns/prod/jazz/process/1.0/">https://elm.example.com/rm/process/project-areas/_F5xhQD-_EeuV6NBd2WfUvQ/timelines</jp:timelines-url>
        <jp06:modified>Wed, 16 Dec 2020 17:07:19 GMT</jp06:modified>
        <jp:history-url xmlns:jp="http://jazz.net/xmlns/prod/jazz/process/1.0/">https://elm.example.com/rm/process/project-areas/_F5xhQD-_EeuV6NBd2WfUvQ/history</jp:history-url>
        <jp:configuration-management-enabled xmlns:jp="http://jazz.net/xmlns/prod/jazz/process/1.0/">true</jp:configuration-management-enabled>
        <jp:configuration-management-mode xmlns:jp="http://jazz.net/xmlns/prod/jazz/process/1.0/">SINGLE</jp:configuration-management-mode>

The response only contains the list of Projects that the Functional User has access to.

Related topics: JazzAuthorizationServer, ELM and OAuth 2.0, OAuth 2.0

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