OAuth 2.0: Part 2 - Getting Keycloak Running

Why Keycloak?

In Part 1, we learned about OAuth 2.0 concepts and the role of different components. Now it’s time to get hands-on.

Keycloak is an open-source Identity and Access Management solution that provides:

• OAuth 2.0 and OpenID Connect support out of the box
• User management and authentication
• Single Sign-On (SSO)
• Social login integration
• A clean admin console

Best of all? It’s free and relatively easy to set up.

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Prerequisites

Before we start, make sure you have:

• Docker and Docker Compose installed on your machine

That’s it. Docker makes this incredibly simple.

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Running Keycloak with Docker Compose

Let’s start by installing Keycloak using Docker Compose.

Step 1: Create docker-compose.yaml

Create a file named docker-compose.yaml with the following content:

services:
  keycloak:
    image: quay.io/keycloak/keycloak:26.0.5
    container_name: keycloak
    command: start-dev
    environment:
      KC_BOOTSTRAP_ADMIN_USERNAME: admin
      KC_BOOTSTRAP_ADMIN_PASSWORD: admin
    ports:
      - "127.0.0.1:9090:8080"

Step 2: Start Keycloak

Now start the Keycloak container:

docker compose up -d

We’re running Keycloak in dev mode here and setting up the admin credentials through environment variables. The container runs on port 8080 internally and is accessible on your local machine at the port 9090.

Step 3: Wait for Keycloak to Start

Keycloak takes a minute or two to start up. You can check the logs:

docker compose logs -f keycloak

Look for a message like:

Running the server in development mode. DO NOT use this configuration in production.

Once you see that, Keycloak is ready!

Step 4: Access the Admin Console

You can now access the Keycloak Admin Console at:

http://localhost:8080

Click on Administration Console and log in with:

• Username: admin
• Password: admin

You’re in! You should see the Keycloak admin dashboard.

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Creating Your First Realm

A realm in Keycloak is like a workspace. It manages a set of users, credentials, roles, and groups.

Step 1: Create a New Realm

1. Click Create Realm
2. Enter a name: demo-realm
3. Click Create

Once it’s created, the new realm demo-realm should automatically be selected.

Step 2: Create a Client

A client represents your application that will use Keycloak for authentication.

1. In the left sidebar, click Clients
2. Click Create client
3. Fill in the details:
   • Client ID: demo-app
   • Client type: OpenID Connect
   • Click Next
4. Configure capabilities:
   • Enable Client authentication
   • Disable Authorization
   • Enable Standard flow and uncheck everything else
   • Click Next
5. Set login settings:

   • Root URL: http://localhost:8080

   • Home URL: http://localhost:8080

   • Valid redirect URIs: http://localhost:8080/callback

   • Web origins: http://localhost:8000

   • Valid post logout redirect URIs: http://localhost:8000

   • Click Save

Step 3: Get Client Credentials

1. Go to the Credentials tab of your client
2. Copy the Client secret (you’ll need this later). Here’s mine: QxDILK2t5mYmODOgke4vSsVEQeeupjAw

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Creating a Test User

Let’s create a user to test authentication:

Step 1: Create User

1. In the left sidebar, click Users
2. Click Add user
3. Fill in:
   • Username: amrit
   • Email: amrit@example.com
   • First name: Amrit
   • Last name: Adhikari
   • Email verified: ON
4. Click Create

Step 2: Set Password

1. Go to the Credentials tab
2. Click Set password
3. Enter password: password123
4. Turn OFF Temporary
5. Click Save

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Testing Your Setup

Time to check if everything is okay so far.

Congratulations! You just authenticated a user.

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What’s Next?

We now have a working Keycloak instance! In the next part of this series, we’ll:

• Explore on how to get Access Token using Authorization Code Flow.

See you in Part 3!