Spring Cloud Gateway is a gateway that provides routing, security, monitoring, and resiliency capabilities for microservices. It acts as an API gateway and sits in front of microservices, routing requests to the appropriate microservice. The gateway uses predicates and filters to route requests and modify requests and responses. It is lightweight and built on reactive principles to enable it to scale to thousands of routes.

1. Spring Cloud Gateway
Cora Iberkleid
@ciberkleid
Developer Advocate, VMware

2. API Gateway Role & Responsibilities
● Routing
● Security
● Monitoring
● Canarying
● Resiliency
● Monolith Strangling
G
A
T
E
W
A
Y
Server Side
MVC App
Microservice A
JS or
Mobile App
Microservice B
Microservice C

3. API Gateways - Then and Now
Many API Management Gateways can be dated
back to SOA and these tend to have been
implemented as centralized servers. But as
microservices became more popular, modern
lightweight independent and decentralized
micro-gateway applications have appeared –
such as Spring Cloud Gateway.
Source: Ben Wilcock
https://spring.io/blog/2019/06/18/getting-started-with-spring-cloud-gateway
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4. Spring Cloud Gateway
Basics

5. Spring Cloud Gateway Foundations

6. Reactive Gateway

7. Gateway Flow
Client Predicates Pre-Filters Global Filters
Post-Filters
Downstream
Service
Gateway
Handler Mapping Web Handler

8. Gateway Flow
Client Predicates Pre-Filters Global Filters
Post-Filters
Downstream
Service
Gateway
Handler Mapping Web Handler
Predicates
● Date/Time
● Cookies
● Headers
● Host
● Method
● Path
● Query Params
● Remote Address
● Weight

9. Gateway Flow
Client Predicates Pre-Filters Global Filters
Post-Filters
Downstream
Service
Gateway
Handler Mapping Web Handler
Pre-Filters
● Headers
● Parameters
● Path
● Circuit Breaker
● Retry
● Rate Limiter
● Redirect
● Save Session
● Size
● Host
● Metrics
● Modify Body

10. Gateway Flow
Client Predicates Pre-Filters Global Filters
Post-Filters
Downstream
Service
Gateway
Handler Mapping Web Handler
Global Filters
● Netty Router
● Web Sockets
● Load Balancer
● Metrics

11. Gateway Flow
Client Predicates Pre-Filters Global Filters
Post-Filters
Downstream
Service
Gateway
Handler Mapping Web Handler
Post Filters
● Set Status
● Headers
● Modify Body

12. Routes: building blocks of a gateway
Defined by:
● ID
● Destination URI
● Collection of predicates (for matching requests to the route)
● Collection of filters (for modifying the request or response)
Specified as:
● Java
● Properties

13. Demo

14. TD Ameritrade @ SpringOne 2019
Poornima Rajendhran
Michael Dennis
Mounika Kikkuru
youtube.com/watch?v=TzKlxr5R-Ew&t=93s
Saravanan Paramasivam
Chris Jackson
youtube.com/watch?v=RRMO4oNptoQ

15. SpringOne 2023, Las Vegas

16. References
Demo:
https://github.com/ciberkleid/spring-cloud-gateway-sample
Spring Cloud Gateway:
https://spring.io/projects/spring-cloud-gateway
https://cloud.spring.io/spring-cloud-gateway/reference/html

17. Thank you! Questions?
Cora Iberkleid
@ciberkleid