Background

• BFE can be configured with Passive Health Check (i.e. Outlier Detection) and use responses from real requests to determine whether an backend instance is healthy.

Description
Add Active Health Check support:

• Actively and periodically send health checking requests to backend.
• Use responses from health checking requests to determine whether an backend instance is he

Currently the release script uses invoke (inv), but the way to make it work is manually installing it's dependencies (pyyaml and semver).

We should make this process straight-forward (probably add a requirements file might be enough, but if you consider it is if needed, add docs too).

Hi，各位大佬，当前计划向社区贡献支持vxlan型组网的实现，先大概描述下价值和大概的实现，看看是否可以接纳,如果OK的话，后续我会把代码提上来。

需求价值

1. 对于云场景，租户之间需要进行vxlan的隔离
2. 公私网之间IP协议族不一致的情况，使用Vxlan进行封装。

大概实现

1. 在发送报文时的vxlan hdr的封装、接收报文时的解封装
2. 封装、解封装后可能引起的报文的分片、聚合.

currently "option forwardfor" cant't be unset, so there is no way to enable it in the default section and disable it in a particular frontend

Problem Summary:

• There was a change to Steeltoe quite some time ago to comply with the Spring spec for returning HTTP 503 in cases of HealthStatus.DOWN or HealthStatus.OUT_OF_SERVICE.

• For 500 series errors, however, HWC is configured by default to substitute a canned message for the http response content - so, instead of getting back any failed health checks, the monitor just gets a 503 w

Add a response timeout value in the timeout message.