Mohammad Abu Musa RABIUL

Posted on Apr 18, 2021

Keycloak Custom Rest Api (Search by user attribute - Keycloak)

#keycloak #customapi #api

In this project we are going to develop and integrate a custom rest api in keycloak server.

About Keycloak

Keycloak is an open source Identity and Access Management solution aimed at modern applications and services. It makes it easy to secure applications and services with little to no code. It provides with following features,

Single-Sign On
Identity Brokering and Social Login
User Federation
Client Adapters
Admin Console
Account Management Console
Standard Protocols: OpenID Connect, OAuth 2.0, and SAML.

Keycloak setup

We are going to use docker container to run Keycloak along with postgreSQL. We have integrated PostgreSQL with Keycloak inside docker-compose.yml file.

To setup the docker containers, run the following command.

docker-compose -f ./docker-compose.yml up -d

Now, your keycloak should run locally on 8090 port.

Keycloak setup and adding user

URL for keycloak http://localhost:8090/

Note: By default keycloak uses Master realm. As you can see we added user in Demo realm. In order to create new realm, do as follow

Now lets create a maven project. I will use VS Code as IDE for this project.However, you can use any IDE of your choice. You can check this link to configure VS Code for Java development.

Project Structure

pom.xml file contains all the required dependencies. You can copy the dependencies in your project.

Create a model user class UserDto.java under models folder.

Create a mapper class that will map keycloak's UserModel class object to UserDto class object. Use import org.keycloak.models.UserModel; to import UserModel class.

Keycloak provides RealmResourceProvider and RealmResourceProviderFactory interfaces that are used to implement custom rest api.
First we create KeyCloakUserApiProvider class that implements RealmResourceProvider interface. We will then define our custome api method named searchUsersByAttribute.

    @GET
    @Path("users/search-by-attr")
    @NoCache
    @Produces({ MediaType.APPLICATION_JSON })
    @Encoded
    public List<UserDto> searchUsersByAttribute(@DefaultValue(defaultAttr) @QueryParam("attr") String attr,
            @QueryParam("value") String value) {
        return session.users().searchForUserByUserAttribute(attr, value, session.getContext().getRealm())
                .stream().map(e -> userMapper.mapToUserDto(e)).collect(Collectors.toList());
    }

The above method filters user list based on user attribute. Default filter attribute is merchant_id.

KeyCloakUserApiProvider class

Use import org.keycloak.services.resource.RealmResourceProvider; to import the interface.

Lets define KeyCloakUserApiProviderFactory class that implements RealmResourceProviderFactory.

KeyCloakUserApiProviderFactory class

Note: Factory instance will remain through out the lifecycle of keycloak server but KeyCloakUserApiProvider instance will be created at run time.

Register the KeyCloakUserApiProviderFactory class to keycloak by creating org.keycloak.services.resource.RealmResourceProviderFactory file under src\main\resources\META-INF\services\ folder.
Next copy the KeyCloakUserApiProviderFactory class name including package information into that file. For an example,

After that, build the maven project by running mvn clean install. This will generate a target folder. Under the target folder there will be {project artifact id}-*.jar file.

Copy that jar file to the Keycloak's standalone/deployments/ directory. For an example, If you run your Keycloak in docker container, you can use the following command:

docker cp <jar_file_path> keycloak:/opt/jboss/keycloak/standalone/deployments/

Test our custom api

Get list of users with merchant_id 1

curl --location --request GET 'http://localhost:8090/auth/realms/demo/userapi-rest/users/search-by-attr?attr=merchant_id&value=1'

You can find the project on this GitHub repository.

If you find this article useful, kindly give a start on GitHub.

Top comments (8)

Hendi Santika • Feb 3 '22

I was modified the docker-compose file. But it didn't work. Do You have any suggestion? Thanks

version: '3.9'

from: github.com/keycloak/keycloak-conta...

volumes:
postgres_data:
driver: local

services:
postgres:
image: postgres
container_name: postgres
volumes:
- postgres_data:/var/lib/postgresql/data
environment:
POSTGRES_DB: keycloak
POSTGRES_USER: keycloak
POSTGRES_PASSWORD: password
pgadmin:
container_name: pgadmin
image: dpage/pgadmin4
environment:
# PGADMIN_DEFAULT_EMAIL: ${PGADMIN_DEFAULT_EMAIL:-pgadmin4@pgadmin.org}
PGADMIN_DEFAULT_EMAIL: hendi@yopmail.com
# PGADMIN_DEFAULT_PASSWORD: ${PGADMIN_DEFAULT_PASSWORD:password}
PGADMIN_DEFAULT_PASSWORD: password
ports:
- "5050:80"
restart: unless-stopped

keycloak:
image: jboss/keycloak:16.1.1
container_name: keycloak
environment:
DB_VENDOR: POSTGRES
DB_ADDR: postgres
DB_DATABASE: keycloak
DB_USER: keycloak
DB_SCHEMA: public
DB_PASSWORD: password
KEYCLOAK_USER: admin
KEYCLOAK_PASSWORD: Pa55w0rd
ports:
- 8090:8080
depends_on:
- postgres

Johannes Reppin • Nov 23 '21

Hi,
this sounds very interesting.
Does this only allow to search for users with the attribute "merchantId"
If I want to search for a different attribute I need to adjust the mapper, right?
Cheers.