Keycloak Expert Skill

Keycloak Expert Skill

Expert guidance for Keycloak identity and access management with deep focus on ABAC implementation.

Table of Contents

1. Core Concepts
2. ABAC Implementation
3. Configuration as Code
4. Integration Patterns
5. Security
6. OpenShift Deployment

Core Concepts

Realm Architecture

• Realm: Isolated tenant with own users, roles, clients, and identity providers
• Client: Application registered for authentication (public, confidential, bearer-only)
• Roles: Realm-level or client-scoped permissions
• Groups: Organizational units for role assignment
• Identity Provider: External authentication source (Azure AD, Google, SAML)

Token Types

• ID Token: User identity for frontends (short-lived)
• Access Token: API authorization (5-30 min)
• Refresh Token: Obtain new tokens without re-login (hours-days)
• RPT (Requesting Party Token): ABAC authorization response containing permissions

ABAC Implementation

ABAC moves authorization logic from application code to Keycloak's centralized policy engine.

ABAC Building Blocks

Resources → What is protected (API endpoints, data, features)
Scopes → Actions on resources (view, edit, delete, admin)
Policies → Rules for access (role-based, time-based, JS-based, aggregate)
Permissions → Connect policies to resources/​scopes

Resource Definition

// Protected resource representing an API endpoint or feature
.createResource("user-profiles")
    .withDisplayName("User Profile Data")
    .withType("urn:app:resources:profile")
    .withUris("/​api/​users/​profile/​*")
    .withScopes("view", "edit", "delete")
    .and()

Policy Types

1. Role Policy: Access based on realm/​client roles
2. Group Policy: Access based on group membership
3. User Policy: Access for specific users
4. Time Policy: Time-window restrictions
5. JavaScript Policy: Custom logic with $evaluation context
6. Aggregate Policy: Combine multiple policies with decision strategy

Permission Creation

.createPermission("admin-profile-management")
    .onResource("user-profiles")
    .withScopes("edit", "delete")
    .withPolicies("admin-role-policy", "business-hours-policy")
    .withDecisionStrategy(DecisionStrategy.UNANIMOUS)
    .and()

UMA Token Exchange (RPT Flow)

Backend validates permissions by exchanging access token for RPT:

curl -X POST "${KEYCLOAK_URL}/​realms/​${REALM}/​protocol/​openid-connect/​token" \
  -H "Authorization: Bearer ${ACCESS_TOKEN}" \
  -d "grant_type=urn:ietf:params:oauth:grant-type:uma-ticket" \
  -d "audience=${CLIENT_ID}" \
  -d "permission=${RESOURCE}#${SCOPE}"

Response Codes:

• 200 + access_token: Permission granted
• 403: Permission denied by policy
• 400: Invalid request or resource

Configuration as Code

For detailed fluent builder patterns, see: references/​fluent-builders.md

Key Builders

• FluentRealmBuilder: Realm settings, token lifespans, security
• FluentClientBuilder: OAuth clients, redirect URIs, flows
• FluentRoleBuilder: Roles, composites, default roles
• FluentAzureIdpBuilder: Azure AD federation with group mapping
• FluentAbacBuilder: Complete ABAC configuration

Example: Complete Realm Setup

// 1. Create realm
FluentRealmBuilder.create()
    .with(keycloakClient)
    .createRealm("toolbox")
    .accessTokenLifespan(1200)  // 20 min
    .ssoSessionIdleTimeout(1800)
    .bruteForceProtected(true)
    .and().apply();

// 2. Configure roles
FluentRoleBuilder.forRealm("toolbox")
    .with(keycloakClient)
    .createRole("admin").withDescription("Administrator").and()
    .createCompositeRole("default-roles-toolbox")
        .addRealmRole("offline_access")
        .addClientRole("account", "view-profile")
        .and()
    .setDefaultRole("default-roles-toolbox")
    .apply();

// 3. Configure client with authorization
FluentClientBuilder.forRealm("toolbox")
    .with(keycloakClient)
    .createClient("toolbox-webui")
        .confidentialClient()
        .enableStandardFlow()
        .enableServiceAccounts()
        .enableAuthorizationServices()
        .addRedirectUri("https://app.example.com/​callback")
        .and()
    .apply();

// 4. Configure ABAC
FluentAbacBuilder.forClient("toolbox", "toolbox-webui")
    .with(abacConfiguration)
    .enableAuthorization(PolicyEnforcementMode.ENFORCING)
    .createResource("mailtemplate")
        .withType("urn:toolbox:resources:mailtemplate")
        .withScopes("view")
        .and()
    .createPolicy("admin-policy")
        .requireRoles("admin")
        .and()
    .createPermission("view-mailtemplate")
        .onScopes("view")
        .withPolicies("admin-policy")
        .and()
    .apply();

Integration Patterns

For complete integration examples, see: references/​integrations.md

Spring Boot Backend (ABAC)

@AbacPolicy(resource = "mailtemplate", action = "view")
@GetMapping("/​mail/​templates")
public List<MailTemplate> getMailTemplates() {
    return mailService.getAllTemplates();
}

The @AbacPolicy annotation triggers AOP-based policy evaluation via UMA:

1. Extract JWT from request
2. Call Keycloak token endpoint with UMA ticket grant
3. If RPT returned → proceed; if 403 → AccessDeniedException

NextAuth.js Frontend

// auth.config.ts
export const authOptions = {
  providers: [
    KeycloakProvider({
      clientId: process.env.AUTH_KEYCLOAK_ID,
      clientSecret: process.env.AUTH_KEYCLOAK_SECRET,
      issuer: process.env.AUTH_KEYCLOAK_ISSUER,
    }),
  ],
  callbacks: {
    jwt: async ({ token, account }) => {
      if (account) {
        token.accessToken = account.access_token;
        token.refreshToken = account.refresh_token;
        token.expiresAt = account.expires_at;
      }
      return token;
    },
  },
};

Azure AD Federation

FluentAzureIdpBuilder.forRealm("toolbox")
    .with(keycloakClient)
    .configureAzureAD(clientId, clientSecret, tenantId)
        .withAlias("azuread")
        .withDisplayName("Azure AD")
        .withDefaultScopes("openid", "profile", "email")
        .trustEmails()
        .and()
    .createMapper("azure-admin-group-mapper")
        .claimToRole()
        .mapClaim("groups")
        .withClaimValue(adminGroupId)
        .toRole("admin")
        .and()
    .apply();

Security

For detailed security guidance, see: references/​security.md

PKCE (Required for All Clients)

Per OAuth 2.0 Security BCP, enable PKCE even for confidential clients:

.createClient("my-app")
    .confidentialClient()
    .enableStandardFlow()
    .enablePKCE()
    .withPkceMethod("S256")
    .and()

Security Hardening Checklist

• Admin console on separate hostname with network restrictions
• TLS enabled, HTTP disabled in production
• Brute force protection enabled
• Rate limiting configured (KC_HTTP_MAX_QUEUED_REQUESTS)
• Event logging enabled for auditing
• Credential rotation procedures documented

Token Revocation

// Revoke refresh token
String revokeEndpoint = authServerUrl + "/​realms/" + realm + "/​protocol/​openid-connect/​revoke";
form.add("token", refreshToken);
form.add("token_type_hint", "refresh_token");

Monitoring

Enable metrics endpoint:

KC_METRICS_ENABLED=true
KC_HEALTH_ENABLED=true

Key alerts: login failures >10/​min, token latency p99 >2s, error rate >1%

OpenShift Deployment

For OpenShift/​Kubernetes specifics, see: references/​deployment.md

Red Hat Keycloak Operator (k8s.keycloak.org/​v2alpha1)

apiVersion: k8s.keycloak.org/​v2alpha1
kind: Keycloak
metadata:
  name: keycloak
spec:
  instances: 1
  db:
    vendor: mysql
    host: mysql.mraas.svc.cluster.local
    usernameSecret:
      name: mysql-db-keycloak-secret
      key: username
    passwordSecret:
      name: mysql-db-keycloak-secret
      key: password
  http:
    httpEnabled: true
    tlsSecret: keycloak-tls
  proxy:
    headers: xforwarded
  hostname:
    hostname: https://keycloak.example.com
    admin: https://admin-keycloak.example.com
    strict: false
  image: custom-keycloak-image:tag
  imagePullSecrets:
    - name: registry-pull-secret
  startOptimized: true
  unsupported:
    podTemplate:
      spec:
        containers:
          - name: keycloak
            env:
              - name: CUSTOM_DB_URL
                valueFrom:
                  secretKeyRef:
                    name: custom-db-secret
                    key: url

Key Configuration Points

• startOptimized: true for production (uses pre-built image)
• proxy.headers: xforwarded for reverse proxy behind ingress
• hostname.strict: false allows multiple hostnames
• Environment variables injected via unsupported.podTemplate

Reference Files

• references/​fluent-builders.md: Complete fluent builder API documentation
• references/​integrations.md: Spring Security, NextAuth.js, and API integration patterns
• references/​deployment.md: OpenShift operator, Docker Compose, environment variables
• references/​abac-patterns.md: Advanced ABAC patterns, policy strategies, UMA protocol details
• references/​security.md: PKCE, hardening, token revocation, monitoring

Quick Reference

Common Environment Variables

Keycloak Admin API Endpoints

Decision Strategies