Building Secure Microservices with Spring Boot, OAuth, and AWS

In today's world of distributed systems, microservices architecture has become a go-to approach for building scalable and resilient applications. One of the key challenges in this architecture is securing communication between microservices. In this blog, we'll explore how to implement OAuth2-based authentication and authorization in a Spring Boot microservices application, and how to deploy it on AWS.

Why OAuth2?

OAuth2 is an open standard for access delegation commonly used for token-based authentication and authorization. It allows applications to access resources on behalf of a user without exposing the user's credentials. By using OAuth2, we can ensure that our microservices interact securely and that only authorized services can access sensitive data.

Setting Up the Environment

Before we dive into the code, let's set up our environment. We'll need the following:

1. Java Development Kit (JDK) 11 or later
2. Spring Boot - for building our microservices
3. Spring Security OAuth2 - for implementing OAuth2
4. AWS - for deploying our services

Step 1: Creating the Authorization Server

The first step is creating an Authorization Server to issue OAuth2 tokens. In Spring Boot, this can be done using the spring-security-oauth2-autoconfigure library.

Add the following dependencies to your pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
        

Create a new class AuthorizationServerConfig:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.oauth2.config.annotation.web.configuration.AuthorizationServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableAuthorizationServer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerEndpointsConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerSecurityConfigurer;

@Configuration
@EnableAuthorizationServer
public class AuthorizationServerConfig extends AuthorizationServerConfigurerAdapter {

    @Override
    public void configure(AuthorizationServerSecurityConfigurer security) throws Exception {
        security.tokenKeyAccess("permitAll()")
                .checkTokenAccess("isAuthenticated()");
    }

    @Override
    public void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {
        // Configure token services and endpoints
    }
}
        

Step 2: Creating Resource Servers

Next, we'll create resource servers that will consume the tokens issued by the authorization server. These resource servers will protect the endpoints and only allow access to users with valid tokens.

Add the following dependencies to your pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
        

Create a new class ResourceServerConfig:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

@Configuration
@EnableWebSecurity
public class ResourceServerConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers("/public").permitAll()
                .anyRequest().authenticated()
                .and()
                .oauth2ResourceServer()
                .jwt();
    }
}
        

Step 3: Deploying to AWS

Now that our microservices are ready, let's deploy them to AWS. We'll use AWS Elastic Beanstalk for deploying our Spring Boot applications.

1. Package Your Application: Build your Spring Boot application using mvn package.
2. Create an Elastic Beanstalk Application:
3. Configure Security Groups:
4. Set Environment Variables:

Conclusion

We've created a secure and scalable architecture by implementing OAuth2 in our Spring Boot microservices and deploying them on AWS. OAuth2 ensures only authorized services can access resources, while AWS provides the infrastructure needed to deploy and manage our microservices.

Building microservices with Spring Boot and securing them with OAuth2 provides a robust foundation for modern applications. Coupling this with AWS's powerful cloud services ensures scalability and reliability, making it a powerful combination for enterprise-level applications.