In the GatewayFilter, I am trying to inject a header into the request like below.
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
//DO SOME AUTHORIZATION OPERATIONS
String jwt = "xxxxx"
exchange.getRequest().getHeaders().add("headerkey", jwt);
return chain.filter(exchange);
}
But I am getting the below error:
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.computeIfAbsent(Collections.java:1535) ~[na:1.8.0_111]
at org.springframework.http.HttpHeaders.add(HttpHeaders.java:1425) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at com.trimble.sample.springcloudgateway.filter.AuthGatewayFilter.filter(AuthGatewayFilter.java:30) ~[classes/:na]
at org.springframework.cloud.gateway.filter.OrderedGatewayFilter.filter(OrderedGatewayFilter.java:44) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
at org.springframework.cloud.gateway.handler.FilteringWebHandler$DefaultGatewayFilterChain.filter(FilteringWebHandler.java:103) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
at org.springframework.cloud.gateway.filter.NettyWriteResponseFilter.filter(NettyWriteResponseFilter.java:62) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
at org.springframework.cloud.gateway.handler.FilteringWebHandler$GatewayFilterAdapter.filter(FilteringWebHandler.java:121) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
at org.springframework.cloud.gateway.filter.OrderedGatewayFilter.filter(OrderedGatewayFilter.java:44) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
at org.springframework.cloud.gateway.handler.FilteringWebHandler$DefaultGatewayFilterChain.filter(FilteringWebHandler.java:103) ~[spring-cloud-gateway-core-2.0.0.BUILD-SNAPSHOT.jar:2.0.0.BUILD-SNAPSHOT]
You can take a look at
org.springframework.cloud.gateway.filter.factory.*GatewayFilterFactory
There are many useful gateway filter implementations.
For your question,
org.springframework.cloud.gateway.filter.factory.AddRequestHeaderGatewayFilterFactory
has a standard implementation.
public class AddRequestHeaderGatewayFilterFactory extends AbstractNameValueGatewayFilterFactory {
@Override
public GatewayFilter apply(NameValueConfig config) {
return (exchange, chain) -> {
ServerHttpRequest request = exchange.getRequest().mutate()
.header(config.getName(), config.getValue())
.build();
return chain.filter(exchange.mutate().request(request).build());
};
}
}