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Add support loadBalancerKey in RibbonRoutingFilter of Zuul for Canary test (#2439)

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* Add support loadBalancerKey in RibbonRoutingFilter

* Add documentation about how to provide a loadBalancerKey to Ribbon

* Add integrationtest for RibbonRoutingFilter's loadBalancerKey support
This commit is contained in:
Yongsung Yoon
2017-11-20 20:28:23 +09:00
committed by Ryan Baxter
parent 6e3b4fdd7b
commit 60c4e1b007
11 changed files with 333 additions and 11 deletions
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26
docs/src/main/asciidoc/spring-cloud-netflix.adoc
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@@ -956,7 +956,33 @@ zuul:
threadPoolKeyPrefix: zuulgw
----
[[how-to-provdie-a-key-to-ribbon]]
=== How to Provide a Key to Ribbon's `IRule`
If you need to provide your own `IRule` implementation to handle a special routing requirement like a canary test,
you probably want to pass some information to the `choose` method of `IRule`.
.com.netflix.loadbalancer.IRule.java
----
public interface IRule{
public Server choose(Object key);
:
----
You can provide some information that will be used to choose a target server by your `IRule` implementation like
the following:
----
RequestContext.getCurrentContext()
.set(FilterConstants.LOAD_BALANCER_KEY, "canary-test");
----
If you put any object into the `RequestContext` with a key `FilterConstants.LOAD_BALANCER_KEY`, it will
be passed to the `choose` method of `IRule` implementation. Above code must be executed before `RibbonRoutingFilter`
is executed and Zuul's pre filter is the best place to do that. You can easily access HTTP headers and query parameters
via `RequestContext` in pre filter, so it can be used to determine `LOAD_BALANCER_KEY` that will be passed to Ribbon.
If you don't put any value with `LOAD_BALANCER_KEY` in `RequestContext`, null will be passed as a parameter of `choose`
method.
[[spring-cloud-feign]]
== Declarative REST Client: Feign