Snippet

Configuring In-Memory Authentication in Spring Security

Spring Security provides authentication mechanisms that can be defined programmatically. An InMemoryUserDetailsManager stores credentials in memory, making it ideal for basic testing and learning authentication setups before moving to database-backed stores.

snippet.java

java

@Configuration
public class SecurityConfig {
 
    @Bean
    public UserDetailsService userDetailsService() {
        UserDetails user = User.withDefaultPasswordEncoder()
                .username("john_doe")
                .password("secret123")
                .roles("USER")
                .build();
        return new InMemoryUserDetailsManager(user);
    }
}

spring

Breakdown

@Bean public UserDetailsService userDetailsService()

Exposes a UserDetailsService bean that Spring Security uses to look up authentication details.

UserDetails user = User.withDefaultPasswordEncoder()

Creates an in-memory user definition builder with default password encoding for development.

return new InMemoryUserDetailsManager(user);

Instantiates and returns the memory-based user manager containing the configured user.

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Configuring In-Memory Authentication in Spring Security

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