Zuul Filters

Overview

• Filter Types
• How to Define a Filter

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Filter Types

• Pre filter
  • Invocation: Invoked before routing the request to the target service.
  • Uses:
    • Request authentication.
    • Request authorization.
    • Make sure all the requests are in the consistent format.
    • Log debug info.
• Post filter
  • Invocation: Invoked after the target service has been triggered and a response is being sent back to the client.
  • Uses:
    • Make sure all the response are in the consistent format.
    • Log debug info.
    • Collect statistics and metrics.
    • Stream the response from the target service to the client.
• Route filter
  • Invocation: Invoked when the request is routing to the target service.
  • Uses:
    • Define a custom routing logic.
    • A/B test.
• Error filter
  • Invocation: Invoke when an error occurs during the execution of other filters.

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How to Define a Filter

To define a custom filter, you need to create a class and implement the ZuulFilter interface. For the ZuulFilter interface, there are 4 methods need to be overridden:

Method	Description
public String filterType()	Type: Define the filter type
public int filterOrder()
shouldFilter()	Criteria: Define the filter will be invoked or not.
public Object run()	Action: The action to be executed if the criteria is met.