Spring-Boot-Microservices-and-Spring-Cloud-sergey

Spring Boot Microservices and Spring Cloud

Links

• https://cloud.spring.io/spring-cloud-gateway/reference/html/#gateway-request-predicates-factories
• https://cloud.spring.io/spring-cloud-gateway/reference/html/#gatewayfilter-factories
• https://cloud.spring.io/spring-cloud-gateway/reference/html/#global-filters
• https://cloud.spring.io/spring-cloud-gateway/reference/html/#httpheadersfilters

Built-in Route Predicate Factories in Spring Cloud API Gateway Below is a list of built-in predicates that you can use when creating routes in Spring Cloud API Gateways. These are built-in predicates and you do not need to write any additional Java code for them to work.

Note: The description of the following built-in predicates is taken from the Spring Cloud API Gateway documentation page.

1. The After Route Predicate Factory

The After route predicate factory takes one parameter, a datetime (which is a java ZonedDateTime). This predicate matches requests that happen after the specified datetime. The following example configures an after route predicate:

spring.cloud.gateway.routes[0].id = after_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = After=2017-01-20T17:42:47.789-07:00[America/Denver]
This route matches any request made after Jan 20, 2017 17:42 Mountain Time (Denver).

2. The Before Route Predicate Factory

The Before route predicate factory takes one parameter, a datetime (which is a java ZonedDateTime). This predicate matches requests that happen before the specified datetime. The following example configures a before route predicate:

spring.cloud.gateway.routes[0].id = before_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Before=2017-01-20T17:42:47.789-07:00[America/Denver]
This route matches any request made before Jan 20, 2017 17:42 Mountain Time (Denver).

3. The Between Route Predicate Factory

The Between route predicate factory takes two parameters, datetime1 and datetime2 which are java ZonedDateTimeobjects. This predicate matches requests that happen after datetime1 and before datetime2. The datetime2 parameter must be after datetime1. The following example configures a between route predicate:

spring.cloud.gateway.routes[0].id = between_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = 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 made 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.

4. The Cookie Route Predicate Factory

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 whose values match the regular expression. The following example configures a cookie route predicate factory:

spring.cloud.gateway.routes[0].id = cookie_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Cookie=chocolate, ch.p
This route matches requests that have a cookie named chocolate whose value matches the ch.p regular expression.

5. The Header Route Predicate Factory

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 whose value matches the regular expression. The following example configures a header route predicate:

spring.cloud.gateway.routes[0].id = header_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Header=X-Request-Id, \d+

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

6. The Host Route Predicate Factory

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. The following example configures a host route predicate:

spring.cloud.gateway.routes[0].id = host_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Host=**.somehost.org,**.anotherhost.org

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

This route matches if the request has a Host header with a value of www.somehost.org or beta.somehost.org or www.anotherhost.org.

This predicate extracts the URI template variables (such as sub, defined in the preceding example) 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 GatewayFilterfactories

7. The Method Route Predicate Factory

The Method Route Predicate Factory takes a methods argument which is one or more parameters: the HTTP methods to match. The following example configures a method route predicate:

spring.cloud.gateway.routes[0].id = method_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Method=GET,POST
This route matches if the request method was a GET or a POST.

8. The Path Route Predicate Factory

The Path Route Predicate Factory takes two parameters: a list of Spring PathMatcher patterns and an optional flag called matchOptionalTrailingSeparator. The following example configures a path route predicate:

spring.cloud.gateway.routes[0].id = path_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Path=/red/{segment},/blue/{segment}

This route matches if the request path was, for example: /red/1 or /red/blue or /blue/green.

This predicate extracts the URI template variables (such as segment, defined in the preceding example) 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 GatewayFilterfactories

9. The Query Route Predicate Factory

The Query route predicate factory takes two parameters: a required param and an optional regexp (which is a Java regular expression). The following example configures a query route predicate:

spring.cloud.gateway.routes[0].id = query_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Query=green

The preceding route matches if the request contained a green query parameter.

10. The RemoteAddr Route Predicate Factory

The RemoteAddr route predicate factory takes a list (min size 1) of sources, which are CIDR-notation (IPv4 or IPv6) strings, such as 192.168.0.1/16 (where 192.168.0.1 is an IP address and 16 is a subnet mask). The following example configures a RemoteAddr route predicate:

spring.cloud.gateway.routes[0].id = remoteaddress_route
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = RemoteAddr=192.168.1.1/24

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

11. The Weight Route Predicate Factory

The Weight route predicate factory takes two arguments: group and weight (an int). The weights are calculated per group. The following example configures a weight route predicate:

spring.cloud.gateway.routes[0].id = weight_high
spring.cloud.gateway.routes[0].uri = https://example.org
spring.cloud.gateway.routes[0].predicates[0] = Weight=group1, 8
 
spring.cloud.gateway.routes[1].id = weight_low
spring.cloud.gateway.routes[1].uri = https://example.org
spring.cloud.gateway.routes[1].predicates[0] = Weight=group1, 2

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

• Below whole architrecture has been covered.