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Load Balancer

The reverse proxy is the common middleware that is accessed by clients, forwards them to backend servers. The reverse proxy is a very core role played by Easegress.

Why Use Easegress as Reverse Proxy

Easegress integrates many features as a reverse proxy with easy configuration.

  • Offload SSL/TLS layer
  • Hot-updated routing without losing requests
  • Intercept invalid requests (according to IP, metadata of requests, credential verification, etc)
  • Adapting requests to satisfy requirements of backend servers
  • Bring more resilience for backend servers (rate limiting, time limiting, circuit breaker, retrying)
  • Load balance for backend servers (static addresses, or integration with service registry)
  • Compression and Caching for response

Basic: Load Balance

The filter Proxy is the filter to fire requests to backend servers. It contains servers group under load balance, whose policy support roundRobin, random, weightedRandom, ipHash, headerHash.

name: pipeline-reverse-proxy
kind: Pipeline
flow:
  - filter: proxy
filters:
  - name: proxy
    kind: Proxy
    pools:
    - servers:
      - url: https://127.0.0.1:9095
      - url: https://127.0.0.1:9096
      - url: https://127.0.0.1:9097
      loadBalance:
        policy: roundRobin

Traffic Adaptor: Change Something of Two-Way Traffic

Sometimes backend applications can't adapt to quick changes of requirements of traffic. Easegress could be an adaptor between new traffic and old applications. There are 2 phases of adaption in reverse proxy: request adaption, response adaption. RequestAdaptor supports the adaption of a method, path, header, and body. ResponseAdaptor supports the adaption of header and body. As you can see, the flow in spec plays a critical role.

name: pipeline-reverse-proxy
kind: Pipeline
flow:
  - filter: requestAdaptor
  - fitter: proxy
  - filter: responseAdaptor
filters:
  - name: requestAdaptor
    kind: RequestAdaptor
    host: easegress.megaease.com
    method: POST
    path:
    addPrefix: /apis/v2
    header:
      set:
        X-Api-Version: v2

  - name: responseAdaptor
    kind: ResponseAdaptor
    header:
      set:
        Server: Easegress v1.0.0
      add:
        X-Easegress-Pipeline: pipeline-reverse-proxy

  - name: proxy
    kind: Proxy
    # ...

For the full YAML, see here

References

Traffic Adaptor: Change Something of Two-Way Traffic

name: pipeline-reverse-proxy
kind: Pipeline
flow:
  - filter: requestAdaptor
  - fitter: proxy
  - filter: responseAdaptor
filters:
  - name: requestAdaptor
    kind: RequestAdaptor
    host: easegress.megaease.com
    method: POST
    path:
    addPrefix: /apis/v2
    header:
      set:
        X-Api-Version: v2

  - name: responseAdaptor
    kind: ResponseAdaptor
    header:
      set:
        Server: Easegress v1.0.0
      add:
        X-Easegress-Pipeline: pipeline-reverse-proxy

  - name: proxy
    kind: Proxy
    pools:
    - servers:
      - url: https://127.0.0.1:9095
      - url: https://127.0.0.1:9096
      - url: https://127.0.0.1:9097
      loadBalance:
        policy: roundRobin