希望网关链路追踪增加自定义标签功能 || I hope gateway link tracking will add custom label functionality #3098
Description
Why do you need it?
当前网关开启链路后功能后只会发送固定的标签，如果遇上需要自定义额外标签名称或内容的场景无法实现，例如我需要获取当前pod的HOSTNAME作为value，podName作为key。
How could it be?
envoy本身支持发送自定义标签，只需要扩展higress的配置项，同时构建higress-config-tracing这个envoyFilter时将相关配置转化为envoy的配置就可以实现
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Why do you need it?
The current gateway will only send fixed labels after opening the link. If you encounter a scenario where you need to customize additional label names or contents, it cannot be implemented. For example, I need to obtain the HOSTNAME of the current pod as the value and the podName as the key.
How could it be?
[Envoy itself supports sending custom tags](https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#envoy-v3-api- msg-extensions-filters-network-http-connection-manager-v3-httpconnectionmanager-tracing), you only need to extend the higress configuration items, and when building the higress-config-tracing envoyFilter, convert the relevant configuration into the envoy configuration.
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