When it comes to building microservices-based fitness apps, authentication and authorization are crucial components that ensure secure interactions between users, services, and data. In this article, we'll explore how to set up a robust authentication and authorization layer using Keycloak, an open-source identity and access management tool.

Authentication and Authorization Setup

To get started, let's build a setup that introduces authentication and authorization to microservices using Keycloak. We'll create an authentication and authorization layer only for the API gateway, while all other services will use infrastructure-level authentication to avoid direct access. This way, our API gateway remains the only public-facing entry point.

Furthermore, if you need to authenticate all services, Keycloak supports single sign-on (SSO), which is easily configurable with Spring Boot.

Setting Up Keycloak

Keycloak is an open-source Identity and Access Management tool that can be run on your local machine or a server. For this example, we'll start a Keycloak instance as a Docker container on our local machine. If you prefer, you can start the Keycloak instance using any other method described here.

To start Keycloak, use the following command:

`docker

$ docker run --restart unless-stopped -p 3306:3306 -d --name mariadb --net keycloak-network -e MYSQL_ROOT_PASSWORD=password -e MYSQL_DATABASE=keycloak -e MYSQL_USER=keycloak -e MYSQL_PASSWORD=password mariadb

$ docker run --restart unless-stopped -d -p 8080:8080 -e KEYCLOAK_USER=admin -e KEYCLOAK_PASSWORD=admin --name keycloak --net keycloak-network jboss/keycloak:12.0.3

`

Now we're ready with our Keycloak instance and can access the Keycloak dashboard for further changes.

Enabling OAuth2.0 With Keycloak

To enable OAuth2.0 authentication for our API gateway, let's start by adding the following dependencies:

`groovy

implementation 'org.springframework.boot:spring-boot-starter-oauth2-client'

implementation 'org.springframework.boot:spring-boot-starter-oauth2-resource-server'

`

Then, apply the following configurations in your application.yml file:

`yaml

#SECURITY BASED CONFIGURATIONS

app:

config:

keycloak:

url: http://localhost:8080/auth

realm: javatodev-internet-banking

spring:

security:

oauth2:

client:

provider:

keycloak:

token-uri: ${app.config.keycloak.url}/realms/${app.config.keycloak.realm}/protocol/openid-connect/token

authorization-uri: ${app.config.keycloak.url}/realms/${app.config.keycloak.realm}/protocol/openid-connect/auth

user-name-attribute: preferred_username

user-info-uri: ${app.config.keycloak.url}/realms/${app.config.keycloak.realm}/protocol/openid-connect/userinfo

jwk-set-uri: ${app.config.keycloak.url}/realms/${app.config.keycloak.realm}/protocol/openid-connect/certs

registration:

internet-banking-core-client:

provider: keycloak

client-id: internet-banking-core-client

client-secret: 0efd3e37-258e-4488-96ae-1dfe34679c9d

authorization-grant-type: authorization_code

redirect-uri: http://localhost:8080/login/oauth2/code/keycloak

scope: openid

resourceserver:

jwt:

jwk-set-uri: ${app.config.keycloak.url}/realms/${app.config.keycloak.realm}/protocol/openid-connect/certs

`

Finally, create a configuration class to complete our setup. This class will serve as the security configuration for our API gateway and enable OAuth2.0 authentication with Keycloak.

By implementing these steps, we've successfully set up a robust authentication and authorization layer for our microservices-based fitness app using Keycloak and Spring Boot.