Shortcut configuration is recognized by the filter name, followed by an equals sign (=), followed by argument values separated by commas (,).

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: after_route
        uri: https://example.org
        predicates:
        - Cookie=mycookie,mycookievalue

The previous sample defines the Cookie Route Predicate Factory with two arguments, the cookie name, mycookie and the value to match mycookievalue.

Fully expanded arguments appear more like standard yaml configuration with name/value pairs. Typically, there will be a name key and an args key. The args key is a map of key value pairs to configure the predicate or filter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: after_route
        uri: https://example.org
        predicates:
        - name: Cookie
          args:
            name: mycookie
            regexp: mycookievalue

This is the full configuration of the shortcut configuration of the Cookie predicate shown above.

The After Route Predicate Factory takes one parameter, a datetime (which is a java ZonedDateTime). This predicate matches requests that happen after the current datetime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: after_route
        uri: https://example.org
        predicates:
        - After=2017-01-20T17:42:47.789-07:00[America/Denver]

This route matches any request after Jan 20, 2017 17:42 Mountain Time (Denver).

The Before Route Predicate Factory takes one parameter, a datetime(which is a java ZonedDateTime). This predicate matches requests that happen before the current datetime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: before_route
        uri: https://example.org
        predicates:
        - Before=2017-01-20T17:42:47.789-07:00[America/Denver]

This route matches any request before Jan 20, 2017 17:42 Mountain Time (Denver).

The Between Route Predicate Factory takes two parameters, datetime1 and datetime2 which are java ZonedDateTime objects. This predicate matches requests that happen after datetime1 and before datetime2. The datetime2 parameter must be after datetime1.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: between_route
        uri: https://example.org
        predicates:
        - Between=2017-01-20T17:42:47.789-07:00[America/Denver], 2017-01-21T17:42:47.789-07:00[America/Denver]

This route matches any request after Jan 20, 2017 17:42 Mountain Time (Denver) and before Jan 21, 2017 17:42 Mountain Time (Denver). This could be useful for maintenance windows.

The Cookie Route Predicate Factory takes two parameters, the cookie name and a regexp (which is a Java regular expression). This predicate matches cookies that have the given name and the value matches the regular expression.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: cookie_route
        uri: https://example.org
        predicates:
        - Cookie=chocolate, ch.p

This route matches the request has a cookie named chocolate who’s value matches the ch.p regular expression.

The Header Route Predicate Factory takes two parameters, the header name and a regexp (which is a Java regular expression). This predicate matches with a header that has the given name and the value matches the regular expression.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: header_route
        uri: https://example.org
        predicates:
        - Header=X-Request-Id, \d+

This route matches if the request has a header named X-Request-Id whos value matches the \d+ regular expression (has a value of one or more digits).

The Host Route Predicate Factory takes one parameter: a list of host name patterns. The pattern is an Ant style pattern with . as the separator. This predicates matches the Host header that matches the pattern.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: host_route
        uri: https://example.org
        predicates:
        - Host=**.somehost.org,**.anotherhost.org

URI template variables are supported as well, such as {sub}.myhost.org.

This route would match if the request has a Host header has the value www.somehost.org or beta.somehost.org or www.anotherhost.org.

This predicate extracts the URI template variables (like sub defined in the example above) as a map of names and values and places it in the ServerWebExchange.getAttributes() with a key defined in ServerWebExchangeUtils.URI_TEMPLATE_VARIABLES_ATTRIBUTE. Those values are then available for use by GatewayFilter Factories

The Method Route Predicate Factory takes a methods argument which is one or more HTTP methods to match.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: method_route
        uri: https://example.org
        predicates:
        - Method=GET,POST

This route would match if the request method was a GET or a POST.

The Path Route Predicate Factory takes two parameter: a list of Spring PathMatcher patterns and an optional flag to matchOptionalTrailingSeparator.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: host_route
        uri: https://example.org
        predicates:
        - Path=/foo/{segment},/bar/{segment}

This route would match if the request path was, for example: /foo/1 or /foo/bar or /bar/baz.

This predicate extracts the URI template variables (like segment defined in the example above) as a map of names and values and places it in the ServerWebExchange.getAttributes() with a key defined in ServerWebExchangeUtils.URI_TEMPLATE_VARIABLES_ATTRIBUTE. Those values are then available for use by GatewayFilter Factories

A utility method is available to make access to these variables easier.

Map<String, String> uriVariables = ServerWebExchangeUtils.getPathPredicateVariables(exchange);

String segment = uriVariables.get("segment");

The Query Route Predicate Factory takes two parameters: a required param and an optional regexp (which is a Java regular expression).

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: query_route
        uri: https://example.org
        predicates:
        - Query=baz

This route would match if the request contained a baz query parameter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: query_route
        uri: https://example.org
        predicates:
        - Query=foo, ba.

This route would match if the request contained a foo query parameter whose value matched the ba. regexp, so bar and baz would match.

The RemoteAddr Route Predicate Factory takes a list (min size 1) of sources, which are CIDR-notation (IPv4 or IPv6) strings, e.g. 192.168.0.1/16 (where 192.168.0.1 is an IP address and 16 is a subnet mask).

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: remoteaddr_route
        uri: https://example.org
        predicates:
        - RemoteAddr=192.168.1.1/24

This route would match if the remote address of the request was, for example, 192.168.1.10.

The Weight Route Predicate Factory takes two arguments group and weight (an int). The weights are calculated per group.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: weight_high
        uri: https://weighthigh.org
        predicates:
        - Weight=group1, 8
      - id: weight_low
        uri: https://weightlow.org
        predicates:
        - Weight=group1, 2

This route would forward ~80% of traffic to https://weighthigh.org and ~20% of traffic to https://weighlow.org

X-Forwarded-For: 0.0.0.1, 0.0.0.2, 0.0.0.3

RemoteAddressResolver resolver = XForwardedRemoteAddressResolver
    .maxTrustedIndex(1);

...

.route("direct-route",
    r -> r.remoteAddr("10.1.1.1", "10.10.1.1/24")
        .uri("https://downstream1")
.route("proxied-route",
    r -> r.remoteAddr(resolver,  "10.10.1.1", "10.10.1.1/24")
        .uri("https://downstream2")
)

The AddRequestHeader GatewayFilter Factory takes a name and value parameter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_request_header_route
        uri: https://example.org
        filters:
        - AddRequestHeader=X-Request-Foo, Bar

This will add X-Request-Foo:Bar header to the downstream request’s headers for all matching requests.

AddRequestHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_request_header_route
        uri: https://example.org
        predicates:
        - Path=/foo/{segment}
        filters:
        - AddRequestHeader=X-Request-Foo, Bar-{segment}

The AddRequestParameter GatewayFilter Factory takes a name and value parameter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_request_parameter_route
        uri: https://example.org
        filters:
        - AddRequestParameter=foo, bar

This will add foo=bar to the downstream request’s query string for all matching requests.

AddRequestParameter is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_request_parameter_route
        uri: https://example.org
        predicates:
        - Host: {segment}.myhost.org
        filters:
        - AddRequestParameter=foo, bar-{segment}

The AddResponseHeader GatewayFilter Factory takes a name and value parameter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_response_header_route
        uri: https://example.org
        filters:
        - AddResponseHeader=X-Response-Foo, Bar

This will add X-Response-Foo:Bar header to the downstream response’s headers for all matching requests.

AddResponseHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: add_response_header_route
        uri: https://example.org
        predicates:
        - Host: {segment}.myhost.org
        filters:
        - AddResponseHeader=foo, bar-{segment}

The DedupeResponseHeader GatewayFilter Factory takes a name parameter and an optional strategy parameter. name can contain a list of header names, space separated.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: dedupe_response_header_route
        uri: https://example.org
        filters:
        - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin

This will remove duplicate values of Access-Control-Allow-Credentials and Access-Control-Allow-Origin response headers in cases when both the gateway CORS logic and the downstream add them.

The DedupeResponseHeader filter also accepts an optional strategy parameter. The accepted values are RETAIN_FIRST (default), RETAIN_LAST, and RETAIN_UNIQUE.

Hystrix is a library from Netflix that implements the circuit breaker pattern. The Hystrix GatewayFilter allows you to introduce circuit breakers to your gateway routes, protecting your services from cascading failures and allowing you to provide fallback responses in the event of downstream failures.

To enable Hystrix GatewayFilters in your project, add a dependency on spring-cloud-starter-netflix-hystrix from Spring Cloud Netflix.

The Hystrix GatewayFilter Factory requires a single name parameter, which is the name of the HystrixCommand.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: hystrix_route
        uri: https://example.org
        filters:
        - Hystrix=myCommandName

This wraps the remaining filters in a HystrixCommand with command name myCommandName.

The Hystrix filter can also accept an optional fallbackUri parameter. Currently, only forward: schemed URIs are supported. If the fallback is called, the request will be forwarded to the controller matched by the URI.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: hystrix_route
        uri: lb://backing-service:8088
        predicates:
        - Path=/consumingserviceendpoint
        filters:
        - name: Hystrix
          args:
            name: fallbackcmd
            fallbackUri: forward:/incaseoffailureusethis
        - RewritePath=/consumingserviceendpoint, /backingserviceendpoint

This will forward to the /incaseoffailureusethis URI when the Hystrix fallback is called. Note that this example also demonstrates (optional) Spring Cloud Netflix Ribbon load-balancing via the lb prefix on the destination URI.

The primary scenario is to use the fallbackUri to an internal controller or handler within the gateway app. However, it is also possible to reroute the request to a controller or handler in an external application, like so:

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: ingredients
        uri: lb://ingredients
        predicates:
        - Path=//ingredients/**
        filters:
        - name: Hystrix
          args:
            name: fetchIngredients
            fallbackUri: forward:/fallback
      - id: ingredients-fallback
        uri: http://localhost:9994
        predicates:
        - Path=/fallback

In this example, there is no fallback endpoint or handler in the gateway application, however, there is one in another app, registered under http://localhost:9994.

In case of the request being forwarded to fallback, the Hystrix Gateway filter also provides the Throwable that has caused it. It’s added to the ServerWebExchange as the ServerWebExchangeUtils.HYSTRIX_EXECUTION_EXCEPTION_ATTR attribute that can be used when handling the fallback within the gateway app.

For the external controller/ handler scenario, headers can be added with exception details. You can find more information on it in the FallbackHeaders GatewayFilter Factory section.

Hystrix settings (such as timeouts) can be configured with global defaults or on a route by route basis using application properties as explained on the Hystrix wiki.

To set a 5 second timeout for the example route above, the following configuration would be used:

application.yml. 

hystrix.command.fallbackcmd.execution.isolation.thread.timeoutInMilliseconds: 5000

The FallbackHeaders factory allows you to add Hystrix execution exception details in headers of a request forwarded to a fallbackUri in an external application, like in the following scenario:

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: ingredients
        uri: lb://ingredients
        predicates:
        - Path=//ingredients/**
        filters:
        - name: Hystrix
          args:
            name: fetchIngredients
            fallbackUri: forward:/fallback
      - id: ingredients-fallback
        uri: http://localhost:9994
        predicates:
        - Path=/fallback
        filters:
        - name: FallbackHeaders
          args:
            executionExceptionTypeHeaderName: Test-Header

In this example, after an execution exception occurs while running the HystrixCommand, the request will be forwarde to the fallback endpoint or handler in an app running on localhost:9994. The headers with the exception type, message and -if available- root cause exception type and message will be added to that request by the FallbackHeaders filter.

The names of the headers can be overwritten in the config by setting the values of the arguments listed below, along with their default values:

You can find more information on how Hystrix works with Gateway in the Hystrix GatewayFilter Factory section.

The MapRequestHeader GatewayFilter Facstory takes 'fromHeader' and 'toHeader' parameters. It creates a new named header (toHeader) and the value is extracted out of an existing named header (fromHeader) from the incoming http request. If the input header does not exist then the filter has no impact. If the new named header already exists then it’s values will be augmented with the new values.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: map_request_header_route
        uri: https://example.org
        filters:
        - MapRequestHeader=Bar, X-Request-Foo

This will add X-Request-Foo:<values> header to the downstream request’s with updated values from the incoming http request Bar header.

The PrefixPath GatewayFilter Factory takes a single prefix parameter.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: prefixpath_route
        uri: https://example.org
        filters:
        - PrefixPath=/mypath

This will prefix /mypath to the path of all matching requests. So a request to /hello, would be sent to /mypath/hello.

The PreserveHostHeader GatewayFilter Factory has no parameters. This filter, sets a request attribute that the routing filter will inspect to determine if the original host header should be sent, rather than the host header determined by the http client.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: preserve_host_route
        uri: https://example.org
        filters:
        - PreserveHostHeader

The RequestRateLimiter GatewayFilter Factory is uses a RateLimiter implementation to determine if the current request is allowed to proceed. If it is not, a status of HTTP 429 - Too Many Requests (by default) is returned.

This filter takes an optional keyResolver parameter and parameters specific to the rate limiter (see below).

keyResolver is a bean that implements the KeyResolver interface. In configuration, reference the bean by name using SpEL. #{@myKeyResolver} is a SpEL expression referencing a bean with the name myKeyResolver.

KeyResolver.java. 

public interface KeyResolver {
	Mono<String> resolve(ServerWebExchange exchange);
}

The KeyResolver interface allows pluggable strategies to derive the key for limiting requests. In future milestones, there will be some KeyResolver implementations.

The default implementation of KeyResolver is the PrincipalNameKeyResolver which retrieves the Principal from the ServerWebExchange and calls Principal.getName().

By default, if the KeyResolver does not find a key, requests will be denied. This behavior can be adjust with the spring.cloud.gateway.filter.request-rate-limiter.deny-empty-key (true or false) and spring.cloud.gateway.filter.request-rate-limiter.empty-key-status-code properties.

	Note
	The RequestRateLimiter is not configurable via the "shortcut" notation. The example below is invalid

application.properties. 

# INVALID SHORTCUT CONFIGURATION
spring.cloud.gateway.routes[0].filters[0]=RequestRateLimiter=2, 2, #{@userkeyresolver}

spring:
  cloud:
    gateway:
      routes:
      - id: requestratelimiter_route
        uri: https://example.org
        filters:
        - name: RequestRateLimiter
          args:
            redis-rate-limiter.replenishRate: 10
            redis-rate-limiter.burstCapacity: 20

@Bean
KeyResolver userKeyResolver() {
    return exchange -> Mono.just(exchange.getRequest().getQueryParams().getFirst("user"));
}

spring:
  cloud:
    gateway:
      routes:
      - id: requestratelimiter_route
        uri: https://example.org
        filters:
        - name: RequestRateLimiter
          args:
            rate-limiter: "#{@myRateLimiter}"
            key-resolver: "#{@userKeyResolver}"

The RedirectTo GatewayFilter Factory takes a status and a url parameter. The status should be a 300 series redirect http code, such as 301. The url should be a valid url. This will be the value of the Location header.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: prefixpath_route
        uri: https://example.org
        filters:
        - RedirectTo=302, https://acme.org

This will send a status 302 with a Location:https://acme.org header to perform a redirect.

The RemoveRequestHeader GatewayFilter Factory takes a name parameter. It is the name of the header to be removed.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: removerequestheader_route
        uri: https://example.org
        filters:
        - RemoveRequestHeader=X-Request-Foo

This will remove the X-Request-Foo header before it is sent downstream.

The RemoveResponseHeader GatewayFilter Factory takes a name parameter. It is the name of the header to be removed.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: removeresponseheader_route
        uri: https://example.org
        filters:
        - RemoveResponseHeader=X-Response-Foo

This will remove the X-Response-Foo header from the response before it is returned to the gateway client.

To remove any kind of sensitive header you should configure this filter for any routes that you may want to do so. In addition you can configure this filter once using spring.cloud.gateway.default-filters and have it applied to all routes.

The RewritePath GatewayFilter Factory takes a path regexp parameter and a replacement parameter. This uses Java regular expressions for a flexible way to rewrite the request path.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: rewritepath_route
        uri: https://example.org
        predicates:
        - Path=/foo/**
        filters:
        - RewritePath=/foo(?<segment>/?.*), $\{segment}

For a request path of /foo/bar, this will set the path to /bar before making the downstream request. Notice the $\ which is replaced with $ because of the YAML spec.

The RewriteLocationResponseHeader GatewayFilter Factory modifies the value of Location response header, usually to get rid of backend specific details. It takes stripVersionMode, locationHeaderName, hostValue, and protocolsRegex parameters.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: rewritelocationresponseheader_route
        uri: http://example.org
        filters:
        - RewriteLocationResponseHeader=AS_IN_REQUEST, Location, ,

For example, for a request POST https://api.example.com/some/object/name, Location response header value https://object-service.prod.example.net/v2/some/object/id will be rewritten as https://api.example.com/some/object/id.

Parameter stripVersionMode has the following possible values: NEVER_STRIP, AS_IN_REQUEST (default), ALWAYS_STRIP.

Parameter hostValue, if provided, will be used to replace the host:port portion of the response Location header. If not provided, the value of the Host request header will be used.

Parameter protocolsRegex must be a valid regex String, against which the protocol name will be matched. If not matched, the filter will do nothing. Default is http|https|ftp|ftps.

The RewriteResponseHeader GatewayFilter Factory takes name, regexp, and replacement parameters. It uses Java regular expressions for a flexible way to rewrite the response header value.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: rewriteresponseheader_route
        uri: https://example.org
        filters:
        - RewriteResponseHeader=X-Response-Foo, , password=[^&]+, password=***

For a header value of /42?user=ford&password=omg!what&flag=true, it will be set to /42?user=ford&password=***&flag=true after making the downstream request. Please use $\ to mean $ because of the YAML spec.

The SaveSession GatewayFilter Factory forces a WebSession::save operation before forwarding the call downstream. This is of particular use when using something like Spring Session with a lazy data store and need to ensure the session state has been saved before making the forwarded call.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: save_session
        uri: https://example.org
        predicates:
        - Path=/foo/**
        filters:
        - SaveSession

If you are integrating Spring Security with Spring Session, and want to ensure security details have been forwarded to the remote process, this is critical.

The SecureHeaders GatewayFilter Factory adds a number of headers to the response at the recommendation from this blog post.

To change the default values set the appropriate property in the spring.cloud.gateway.filter.secure-headers namespace:

To disable the default values set the property spring.cloud.gateway.filter.secure-headers.disable with comma separated values.

	Note
	Need use lowercase and full name of secure headers.

Example: spring.cloud.gateway.filter.secure-headers.disable=x-frame-options,strict-transport-security

The SetPath GatewayFilter Factory takes a path template parameter. It offers a simple way to manipulate the request path by allowing templated segments of the path. This uses the uri templates from Spring Framework. Multiple matching segments are allowed.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setpath_route
        uri: https://example.org
        predicates:
        - Path=/foo/{segment}
        filters:
        - SetPath=/{segment}

For a request path of /foo/bar, this will set the path to /bar before making the downstream request.

The SetRequestHeader GatewayFilter Factory takes name and value parameters.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setrequestheader_route
        uri: https://example.org
        filters:
        - SetRequestHeader=X-Request-Foo, Bar

This GatewayFilter replaces all headers with the given name, rather than adding. So if the downstream server responded with a X-Request-Foo:1234, this would be replaced with X-Request-Foo:Bar, which is what the downstream service would receive.

SetRequestHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setrequestheader_route
        uri: https://example.org
        predicates:
        - Host: {segment}.myhost.org
        filters:
        - SetRequestHeader=foo, bar-{segment}

The SetResponseHeader GatewayFilter Factory takes name and value parameters.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setresponseheader_route
        uri: https://example.org
        filters:
        - SetResponseHeader=X-Response-Foo, Bar

This GatewayFilter replaces all headers with the given name, rather than adding. So if the downstream server responded with a X-Response-Foo:1234, this would be replaced with X-Response-Foo:Bar, which is what the gateway client would receive.

SetResponseHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setresponseheader_route
        uri: https://example.org
        predicates:
        - Host: {segment}.myhost.org
        filters:
        - SetResponseHeader=foo, bar-{segment}

The SetStatus GatewayFilter Factory takes a single status parameter. It must be a valid Spring HttpStatus. It may be the integer value 404 or the string representation of the enumeration NOT_FOUND.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: setstatusstring_route
        uri: https://example.org
        filters:
        - SetStatus=BAD_REQUEST
      - id: setstatusint_route
        uri: https://example.org
        filters:
        - SetStatus=401

In either case, the HTTP status of the response will be set to 401.

The StripPrefix GatewayFilter Factory takes one paramter, parts. The parts parameter indicated the number of parts in the path to strip from the request before sending it downstream.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: nameRoot
        uri: http://nameservice
        predicates:
        - Path=/name/**
        filters:
        - StripPrefix=2

When a request is made through the gateway to /name/bar/foo the request made to nameservice will look like http://nameservice/foo.

The Retry GatewayFilter Factory support following set of parameters:

The following defaults are configured for Retry filter if enabled:

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: retry_test
        uri: http://localhost:8080/flakey
        predicates:
        - Host=*.retry.com
        filters:
        - name: Retry
          args:
            retries: 3
            statuses: BAD_GATEWAY
            methods: GET,POST
            backoff:
              firstBackoff: 10ms
              maxBackoff: 50ms
              factor: 2
              basedOnPreviousValue: false

Note

When using the retry filter with a forward: prefixed URL, the target endpoint should be written carefully so that in case of an error it does not do anything that could result in a response being sent to the client and committed. For example, if the target endpoint is an annotated controller, the target controller method should not return ResponseEntity with an error status code. Instead it should throw an Exception, or signal an error, e.g. via a Mono.error(ex) return value, which the retry filter can be configured to handle by retrying.

	Warning
	When using the retry filter with any HTTP method with a body, the body will be cached and the gateway will become memory constrained. The body is cached in a request attribute defined by ServerWebExchangeUtils.CACHED_REQUEST_BODY_ATTR. The type of the object is a org.springframework.core.io.buffer.DataBuffer.

The RequestSize GatewayFilter Factory can restrict a request from reaching the downstream service , when the request size is greater than the permissible limit. The filter takes a maxSize parameter which is the permissible size limit of the request. The maxSize is a `DataSize type, so values can be defined as a number followed by an optional DataUnit suffix such as 'KB' or 'MB'. The default is 'B' for bytes.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: request_size_route
      uri: http://localhost:8080/upload
      predicates:
      - Path=/upload
      filters:
      - name: RequestSize
        args:
          maxSize: 5000000

The RequestSize GatewayFilter Factory set the response status as 413 Payload Too Large with a additional header errorMessage when the Request is rejected due to size. Following is an example of such an errorMessage .

errorMessage : Request size is larger than permissible limit. Request size is 6.0 MB where permissible limit is 5.0 MB

	Note
	The default Request size will be set to 5 MB if not provided as filter argument in route definition.

This filter is considered BETA and the API may change in the future

The ModifyRequestBody filter can be used to modify the request body before it is sent downstream by the Gateway.

	Note
	This filter can only be configured using the Java DSL

@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("rewrite_request_obj", r -> r.host("*.rewriterequestobj.org")
            .filters(f -> f.prefixPath("/httpbin")
                .modifyRequestBody(String.class, Hello.class, MediaType.APPLICATION_JSON_VALUE,
                    (exchange, s) -> return Mono.just(new Hello(s.toUpperCase())))).uri(uri))
        .build();
}

static class Hello {
    String message;

    public Hello() { }

    public Hello(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

This filter is considered BETA and the API may change in the future

The ModifyResponseBody filter can be used to modify the response body before it is sent back to the Client.

	Note
	This filter can only be configured using the Java DSL

@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("rewrite_response_upper", r -> r.host("*.rewriteresponseupper.org")
            .filters(f -> f.prefixPath("/httpbin")
        		.modifyResponseBody(String.class, String.class,
        		    (exchange, s) -> Mono.just(s.toUpperCase()))).uri(uri)
        .build();
}

If you would like to add a filter and apply it to all routes you can use spring.cloud.gateway.default-filters. This property takes a list of filters

application.yml. 

spring:
  cloud:
    gateway:
      default-filters:
      - AddResponseHeader=X-Response-Default-Foo, Default-Bar
      - PrefixPath=/httpbin

When a request comes in (and matches a Route) the Filtering Web Handler will add all instances of GlobalFilter and all route specific instances of GatewayFilter to a filter chain. This combined filter chain is sorted by the org.springframework.core.Ordered interface, which can be set by implementing the getOrder() method.

As Spring Cloud Gateway distinguishes between "pre" and "post" phases for filter logic execution (see: How it Works), the filter with the highest precedence will be the first in the "pre"-phase and the last in the "post"-phase.

ExampleConfiguration.java. 

@Bean
public GlobalFilter customFilter() {
    return new CustomGlobalFilter();
}

public class CustomGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        log.info("custom global filter");
        return chain.filter(exchange);
    }

    @Override
    public int getOrder() {
        return -1;
    }
}

The ForwardRoutingFilter looks for a URI in the exchange attribute ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR. If the url has a forward scheme (ie forward:///localendpoint), it will use the Spring DispatcherHandler to handler the request. The path part of the request URL will be overridden with the path in the forward URL. The unmodified original url is appended to the list in the ServerWebExchangeUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR attribute.

The LoadBalancerClientFilter looks for a URI in the exchange attribute ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR. If the url has a lb scheme (ie lb://myservice), it will use the Spring Cloud LoadBalancerClient to resolve the name (myservice in the previous example) to an actual host and port and replace the URI in the same attribute. The unmodified original url is appended to the list in the ServerWebExchangeUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR attribute. The filter will also look in the ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR attribute to see if it equals lb and then the same rules apply.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: myRoute
        uri: lb://service
        predicates:
        - Path=/service/**

	Note
	By default when a service instance cannot be found in the LoadBalancer a 503 will be returned. You can configure the Gateway to return a 404 by setting spring.cloud.gateway.loadbalancer.use404=true.

Note

The isSecure value of the ServiceInstance returned from the LoadBalancer will override the scheme specified in the request made to the Gateway. For example, if the request comes into the Gateway over HTTPS but the ServiceInstance indicates it is not secure, then the downstream request will be made over HTTP. The opposite situation can also apply. However if GATEWAY_SCHEME_PREFIX_ATTR is specified for the route in the Gateway configuration, the prefix will be stripped and the resulting scheme from the route URL will override the ServiceInstance configuration.

	Warning
	LoadBalancerClientFilter uses a blocking Ribbon LoadBalancerClient under the hood. We suggest you use ReactiveLoadBalancerClientFilter instead. You can switch to using it by adding org.springframework.cloud:spring-cloud-loadbalancer dependency to your project and setting the value of the spring.cloud.loadbalancer.ribbon.enabled to false.

The ReactiveLoadBalancerClientFilter looks for a URI in the exchange attribute ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR. If the url has a lb scheme (ie lb://myservice), it will use the Spring Cloud ReactorLoadBalancer to resolve the name (myservice in the previous example) to an actual host and port and replace the URI in the same attribute. The unmodified original url is appended to the list in the ServerWebExchangeUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR attribute. The filter will also look in the ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR attribute to see if it equals lb and then the same rules apply.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      - id: myRoute
        uri: lb://service
        predicates:
        - Path=/service/**

	Note
	By default when a service instance cannot be found by the ReactorLoadBalancer, a 503 will be returned. You can configure the Gateway to return a 404 by setting spring.cloud.gateway.loadbalancer.use404=true.

Note

The isSecure value of the ServiceInstance returned from the ReactiveLoadBalancerClientFilter will override the scheme specified in the request made to the Gateway. For example, if the request comes into the Gateway over HTTPS but the ServiceInstance indicates it is not secure, then the downstream request will be made over HTTP. The opposite situation can also apply. However if GATEWAY_SCHEME_PREFIX_ATTR is specified for the route in the Gateway configuration, the prefix will be stripped and the resulting scheme from the route URL will override the ServiceInstance configuration.

The Netty Routing Filter runs if the url located in the ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR exchange attribute has a http or https scheme. It uses the Netty HttpClient to make the downstream proxy request. The response is put in the ServerWebExchangeUtils.CLIENT_RESPONSE_ATTR exchange attribute for use in a later filter. (There is an experimental WebClientHttpRoutingFilter that performs the same function, but does not require netty)

The NettyWriteResponseFilter runs if there is a Netty HttpClientResponse in the ServerWebExchangeUtils.CLIENT_RESPONSE_ATTR exchange attribute. It is run after all other filters have completed and writes the proxy response back to the gateway client response. (There is an experimental WebClientWriteResponseFilter that performs the same function, but does not require netty)

The RouteToRequestUrlFilter runs if there is a Route object in the ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR exchange attribute. It creates a new URI, based off of the request URI, but updated with the URI attribute of the Route object. The new URI is placed in the ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR exchange attribute.

If the URI has a scheme prefix, such as lb:ws://serviceid, the lb scheme is stripped from the URI and placed in the ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR for use later in the filter chain.

The Websocket Routing Filter runs if the url located in the ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR exchange attribute has a ws or wss scheme. It uses the Spring Web Socket infrastructure to forward the Websocket request downstream.

Websockets may be load-balanced by prefixing the URI with lb, such as lb:ws://serviceid.

	Note
	If you are using SockJS as a fallback over normal http, you should configure a normal HTTP route as well as the Websocket Route.

application.yml. 

spring:
  cloud:
    gateway:
      routes:
      # SockJS route
      - id: websocket_sockjs_route
        uri: http://localhost:3001
        predicates:
        - Path=/websocket/info/**
      # Normal Websocket route
      - id: websocket_route
        uri: ws://localhost:3001
        predicates:
        - Path=/websocket/**

To enable Gateway Metrics add spring-boot-starter-actuator as a project dependency. Then, by default, the Gateway Metrics Filter runs as long as the property spring.cloud.gateway.metrics.enabled is not set to false. This filter adds a timer metric named "gateway.requests" with the following tags:

These metrics are then available to be scraped from /actuator/metrics/gateway.requests and can be easily integrated with Prometheus to create a Grafana dashboard.

	Note
	To enable the prometheus endpoint add micrometer-registry-prometheus as a project dependency.

After the Gateway has routed a ServerWebExchange it will mark that exchange as "routed" by adding gatewayAlreadyRouted to the exchange attributes. Once a request has been marked as routed, other routing filters will not route the request again, essentially skipping the filter. There are convenience methods that you can use to mark an exchange as routed or check if an exchange has already been routed.

The Forwarded Headers Filter creates a Forwarded header to send to the downstream service. It adds the Host header, scheme and port of the current request to any existing Forwarded header.

The RemoveHopByHop Headers Filter removes headers from forwarded requests. The default list of headers that is removed comes from the IETF.

To change this, set the spring.cloud.gateway.filter.remove-non-proxy-headers.headers property to the list of header names to remove.

The XForwarded Headers Filter creates various a X-Forwarded-* headers to send to the downstream service. It users the Host header, scheme, port and path of the current request to create the various headers.

Creating of individual headers can be controlled by the following boolean properties (defaults to true):

Appending multiple headers can be controlled by the following boolean properties (defaults to true):

The Gateway maintains a client pool that it uses to route to backends. When communicating over https the client initiates a TLS handshake. A number of timeouts are assoicated with this handshake. These timeouts can be configured (defaults shown):

application.yml. 

spring:
  cloud:
    gateway:
      httpclient:
        ssl:
          handshake-timeout-millis: 10000
          close-notify-flush-timeout-millis: 3000
          close-notify-read-timeout-millis: 0

To allow for simple configuration in Java, there is a fluent API defined in the RouteLocatorBuilder bean.

GatewaySampleApplication.java. 

// static imports from GatewayFilters and RoutePredicates
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder, ThrottleGatewayFilterFactory throttle) {
    return builder.routes()
            .route(r -> r.host("**.abc.org").and().path("/image/png")
                .filters(f ->
                        f.addResponseHeader("X-TestHeader", "foobar"))
                .uri("http://httpbin.org:80")
            )
            .route(r -> r.path("/image/webp")
                .filters(f ->
                        f.addResponseHeader("X-AnotherHeader", "baz"))
                .uri("http://httpbin.org:80")
            )
            .route(r -> r.order(-1)
                .host("**.throttle.org").and().path("/get")
                .filters(f -> f.filter(throttle.apply(1,
                        1,
                        10,
                        TimeUnit.SECONDS)))
                .uri("http://httpbin.org:80")
            )
            .build();
}

This style also allows for more custom predicate assertions. The predicates defined by RouteDefinitionLocator beans are combined using logical and. By using the fluent Java API, you can use the and(), or() and negate() operators on the Predicate class.

The Gateway can be configured to create routes based on services registered with a DiscoveryClient compatible service registry.

To enable this, set spring.cloud.gateway.discovery.locator.enabled=true and make sure a DiscoveryClient implementation is on the classpath and enabled (such as Netflix Eureka, Consul or Zookeeper).

spring.cloud.gateway.discovery.locator.predicates[0].name: Path
spring.cloud.gateway.discovery.locator.predicates[0].args[pattern]: "'/'+serviceId+'/**'"
spring.cloud.gateway.discovery.locator.predicates[1].name: Host
spring.cloud.gateway.discovery.locator.predicates[1].args[pattern]: "'**.foo.com'"
spring.cloud.gateway.discovery.locator.filters[0].name: Hystrix
spring.cloud.gateway.discovery.locator.filters[0].args[name]: serviceId
spring.cloud.gateway.discovery.locator.filters[1].name: RewritePath
spring.cloud.gateway.discovery.locator.filters[1].args[regexp]: "'/' + serviceId + '/(?<remaining>.*)'"
spring.cloud.gateway.discovery.locator.filters[1].args[replacement]: "'/${remaining}'"

A new, more verbose format has been added to Gateway. This adds more detail to each route allowing to view the predicates and filters associated to each route along with any configuration that is available.

/actuator/gateway/routes

[
  {
    "predicate": "(Hosts: [**.addrequestheader.org] && Paths: [/headers], match trailing slash: true)",
    "route_id": "add_request_header_test",
    "filters": [
      "[[AddResponseHeader X-Response-Default-Foo = 'Default-Bar'], order = 1]",
      "[[AddRequestHeader X-Request-Foo = 'Bar'], order = 1]",
      "[[PrefixPath prefix = '/httpbin'], order = 2]"
    ],
    "uri": "lb://testservice",
    "order": 0
  }
]

To enable this feature, set the following property:

application.properties. 

spring.cloud.gateway.actuator.verbose.enabled=true

This will default to true in a future release.

To clear the routes cache, make a POST request to /actuator/gateway/refresh. The request returns a 200 without response body.

To retrieve the routes defined in the gateway, make a GET request to /actuator/gateway/routes. The resulting response is similar to the following:

[{
  "route_id": "first_route",
  "route_object": {
    "predicate": "org.springframework.cloud.gateway.handler.predicate.PathRoutePredicateFactory$$Lambda$432/1736826640@1e9d7e7d",
    "filters": [
      "OrderedGatewayFilter{delegate=org.springframework.cloud.gateway.filter.factory.PreserveHostHeaderGatewayFilterFactory$$Lambda$436/674480275@6631ef72, order=0}"
    ]
  },
  "order": 0
},
{
  "route_id": "second_route",
  "route_object": {
    "predicate": "org.springframework.cloud.gateway.handler.predicate.PathRoutePredicateFactory$$Lambda$432/1736826640@cd8d298",
    "filters": []
  },
  "order": 0
}]

The response contains details of all the routes defined in the gateway. The following table describes the structure of each element (i.e., a route) of the response.

To retrieve information about a single route, make a GET request to /actuator/gateway/routes/{id} (e.g., /actuator/gateway/routes/first_route). The resulting response is similar to the following:

{
  "id": "first_route",
  "predicates": [{
    "name": "Path",
    "args": {"_genkey_0":"/first"}
  }],
  "filters": [],
  "uri": "https://www.uri-destination.org",
  "order": 0
}]

The following table describes the structure of the response.

To create a route, make a POST request to /gateway/routes/{id_route_to_create} with a JSON body that specifies the fields of the route (see the previous subsection).

To delete a route, make a DELETE request to /gateway/routes/{id_route_to_delete}.

The table below summarises the Spring Cloud Gateway actuator endpoints. Note that each endpoint has /actuator/gateway as the base-path.

Below are some useful loggers that contain valuable trouble shooting infomration at the DEBUG and TRACE levels.

The Reactor Netty HttpClient and HttpServer can have wiretap enabled. When combined with setting the reactor.netty log level to DEBUG or TRACE will enable logging of information such as headers and bodies sent and received across the wire. To enable this, set spring.cloud.gateway.httpserver.wiretap=true and/or spring.cloud.gateway.httpclient.wiretap=true for the HttpServer and HttpClient respectively.

In order to write a Route Predicate you will need to implement RoutePredicateFactory. There is an abstract class called AbstractRoutePredicateFactory which you can extend.

MyRoutePredicateFactory.java. 

public class MyRoutePredicateFactory extends AbstractRoutePredicateFactory<HeaderRoutePredicateFactory.Config> {

    public MyRoutePredicateFactory() {
        super(Config.class);
    }

    @Override
    public Predicate<ServerWebExchange> apply(Config config) {
        // grab configuration from Config object
        return exchange -> {
            //grab the request
            ServerHttpRequest request = exchange.getRequest();
            //take information from the request to see if it
            //matches configuration.
            return matches(config, request);
        };
    }

    public static class Config {
        //Put the configuration properties for your filter here
    }

}

In order to write a GatewayFilter you will need to implement GatewayFilterFactory. There is an abstract class called AbstractGatewayFilterFactory which you can extend.

PreGatewayFilterFactory.java. 

public class PreGatewayFilterFactory extends AbstractGatewayFilterFactory<PreGatewayFilterFactory.Config> {

	public PreGatewayFilterFactory() {
		super(Config.class);
	}

	@Override
	public GatewayFilter apply(Config config) {
		// grab configuration from Config object
		return (exchange, chain) -> {
			//If you want to build a "pre" filter you need to manipulate the
			//request before calling chain.filter
			ServerHttpRequest.Builder builder = exchange.getRequest().mutate();
			//use builder to manipulate the request
			return chain.filter(exchange.mutate().request(request).build());
		};
	}

	public static class Config {
		//Put the configuration properties for your filter here
	}

}

PostGatewayFilterFactory.java. 

public class PostGatewayFilterFactory extends AbstractGatewayFilterFactory<PostGatewayFilterFactory.Config> {

	public PostGatewayFilterFactory() {
		super(Config.class);
	}

	@Override
	public GatewayFilter apply(Config config) {
		// grab configuration from Config object
		return (exchange, chain) -> {
			return chain.filter(exchange).then(Mono.fromRunnable(() -> {
				ServerHttpResponse response = exchange.getResponse();
				//Manipulate the response in some way
			}));
		};
	}

	public static class Config {
		//Put the configuration properties for your filter here
	}

}

In order to write a custom global filter, you will need to implement GlobalFilter interface. This will apply the filter to all requests.

Example of how to set up a Global Pre and Post filter, respectively

@Bean
public GlobalFilter customGlobalFilter() {
    return (exchange, chain) -> exchange.getPrincipal()
        .map(Principal::getName)
        .defaultIfEmpty("Default User")
        .map(userName -> {
          //adds header to proxied request
          exchange.getRequest().mutate().header("CUSTOM-REQUEST-HEADER", userName).build();
          return exchange;
        })
        .flatMap(chain::filter);
}

@Bean
public GlobalFilter customGlobalPostFilter() {
    return (exchange, chain) -> chain.filter(exchange)
        .then(Mono.just(exchange))
        .map(serverWebExchange -> {
          //adds header to response
          serverWebExchange.getResponse().getHeaders().set("CUSTOM-RESPONSE-HEADER",
              HttpStatus.OK.equals(serverWebExchange.getResponse().getStatusCode()) ? "It worked": "It did not work");
          return serverWebExchange;
        })
        .then();
}