# Keycloak Expert

> Expert guidance on Keycloak identity and access management, including ABAC (Attribute-Based Access Control), OIDC/OAuth2 flows, realm/client configuration, identity provider integration (Azure AD), custom SPI providers, and Configuration as Code. Use this skill when working with: Keycloak realm setup, client configuration, role management, authorization services, ABAC policies/resources/scopes/permissions, UMA protocol, RPT tokens, policy evaluation, Azure AD federation, group-to-role mapping, custom protocol mappers, username mappers, fluent builder APIs for Keycloak configuration, OpenShift/Kubernetes operator deployment, Spring Security + Keycloak integration, NextAuth.js + Keycloak, or any Keycloak administration and development tasks.

- Skill: `majiayu000/keycloak-expert` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/keycloak-expert`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/keycloak-expert/raw
- Safety review: pending (external: skill-scanner PASS, skillspector CAUTION)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/keycloak-expert

---


# Keycloak Expert Skill

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

## Table of Contents
1. [Core Concepts](#core-concepts)
2. [ABAC Implementation](#abac-implementation)
3. [Configuration as Code](#configuration-as-code)
4. [Integration Patterns](#integration-patterns)
5. [OpenShift Deployment](#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
```java
// 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
```java
.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:
```bash
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](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
```java
// 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](references/integrations.md)**

### Spring Boot Backend (ABAC)
```java
@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
```typescript
// 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
```java
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();
```

## OpenShift Deployment

For OpenShift/Kubernetes specifics, see: **[references/deployment.md](references/deployment.md)**

### Red Hat Keycloak Operator (k8s.keycloak.org/v2alpha1)
```yaml
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](references/fluent-builders.md)**: Complete fluent builder API documentation
- **[references/integrations.md](references/integrations.md)**: Spring Security, NextAuth.js, and API integration patterns
- **[references/deployment.md](references/deployment.md)**: OpenShift operator, Docker Compose, environment variables
- **[references/abac-patterns.md](references/abac-patterns.md)**: Advanced ABAC patterns, policy strategies, UMA protocol details

## Quick Reference

### Common Environment Variables
| Variable | Description |
|----------|-------------|
| `KEYCLOAK_ADMIN` | Admin username |
| `KEYCLOAK_ADMIN_PASSWORD` | Admin password |
| `KC_DB` | Database type (mysql, postgres) |
| `KC_DB_URL` | JDBC connection string |
| `AZURE_CLIENT_ID` | Azure AD app client ID |
| `AZURE_CLIENT_SECRET` | Azure AD app secret |
| `AZURE_TENANT_ID` | Azure AD tenant |

### Keycloak Admin API Endpoints
| Endpoint | Purpose |
|----------|---------|
| `/admin/realms/{realm}` | Realm management |
| `/admin/realms/{realm}/clients` | Client management |
| `/admin/realms/{realm}/clients/{id}/authz` | Authorization services |
| `/realms/{realm}/protocol/openid-connect/token` | Token endpoint |
| `/realms/{realm}/protocol/openid-connect/certs` | JWKS endpoint |

### Decision Strategies
| Strategy | Behavior |
|----------|----------|
| `UNANIMOUS` | All policies must permit |
| `AFFIRMATIVE` | At least one policy must permit |
| `CONSENSUS` | Majority of policies must permit |