Add websocket-authentication sample

websocket-authentication/src/main/java/com/example/greeting/WebFluxSecurityConfig.java

@@ -0,0 +1,34 @@
+package com.example.greeting;
+
+import java.security.interfaces.RSAPublicKey;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.graphql.server.WebSocketGraphQlInterceptor;
+import org.springframework.graphql.server.support.BearerTokenAuthenticationExtractor;
+import org.springframework.graphql.server.webflux.AuthenticationWebSocketInterceptor;
+import org.springframework.security.config.web.server.ServerHttpSecurity;
+import org.springframework.security.oauth2.jwt.NimbusReactiveJwtDecoder;
+import org.springframework.security.oauth2.server.resource.authentication.JwtReactiveAuthenticationManager;
+import org.springframework.security.web.server.SecurityWebFilterChain;
+
+@Configuration
+@ConditionalOnMissingClass("org.springframework.web.servlet.DispatcherServlet")
+public class WebFluxSecurityConfig {
+
+	@Bean
+	SecurityWebFilterChain webFilters(ServerHttpSecurity http) {
+		http.authorizeExchange((authorize) -> authorize.anyExchange().permitAll());
+		return http.build();
+	}
+
+	@Bean
+	public WebSocketGraphQlInterceptor authenticationInterceptor(@Value("classpath:simple.pub") RSAPublicKey pub) {
+		return new AuthenticationWebSocketInterceptor(
+				new BearerTokenAuthenticationExtractor(),
+				new JwtReactiveAuthenticationManager(NimbusReactiveJwtDecoder.withPublicKey(pub).build()));
+	}
+
+}