修改URL 对于k8s service 的访问

指定流量路由的权重

指定请求的host header

可以使用catch-all 进行默认处理，比如404
参考
---
apiVersion: ambassador/v0
kind: Mapping
name: catch-all
prefix: /
service: https://www.getambassador.io

参考
最简单的例子
---
apiVersion: ambassador/v0
kind:  Mapping
name:  qotm_mapping
prefix: /qotm/
service: http://qotm
一个cqrs 的例子
---
apiVersion: ambassador/v0
kind: Mapping
name: cqrs_get_mapping
prefix: /cqrs/
method: GET
service: getcqrs
---
apiVersion: ambassador/v0
kind: Mapping
name: cqrs_put_mapping
prefix: /cqrs/
method: PUT
service: putcqrs
更多配置参考：https://www.getambassador.io/reference/mappings.html 

主要是为了解决一些微服务框架基于主机头进行路由
参考：
---
apiVersion: ambassador/v0
kind: Mapping
name: httpbin_mapping
prefix: /httpbin/
service: httpbin.org:80
host_rewrite: httpbin.org

基于http header HOST 的mapping
参考
---
apiVersion: ambassador/v0
kind:  Mapping
name:  qotm_mapping
prefix: /qotm/
service: qotm1
---
apiVersion: ambassador/v0
kind:  Mapping
name:  qotm_mapping
prefix: /qotm/
host: qotm.datawire.io
service: qotm2
---
apiVersion: ambassador/v0
kind:  Mapping
name:  qotm_mapping
prefix: /qotm/
host: "^qotm[2-9]\\.datawire\\.io$"
host_regex: true
service: qotm3

对于包含特定header 的请求进行mapping
参考
---
apiVersion: ambassador/v0
kind:  Mapping
name:  qotm_mapping
prefix: /qotm/
headers:x-qotm-mode: canaryx-random-header: datawire
service: qotm

进行跨域的处理（基于cors）
参考
apiVersion: ambassador/v0
kind:  Mapping
name:  cors_mapping
prefix: /cors/
service: cors-example
cors:origins: http://foo.example,http://bar.examplemethods: POST, GET, OPTIONSheaders: Content-Typecredentials: trueexposed_headers: X-Custom-Headermax_age: "86400"