通过 Event Hooks 功能，可以在 Kong Gateway 中发生特定事件时收到通知。如果你想监控新管理员或服务的创建，或插件限流等事件，这会非常有用。
这是什么功能？#
Event Hooks 有四种类型：
- webhook：发送定义格式的 POST 请求
- webhook-custom：发送自定义 HTTP 请求
- log：将事件内容记录到 Kong Gateway 的错误日志中
- lambda：触发预定义的 Lua 函数
本文将演示 webhook-custom 和 log 的用法。
查看可用事件#
Kong Gateway 的 admin API 提供了 /event-hooks/sources 端点，可以查看可用的 source、event 及参数。数据较多，这里只摘录部分：
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| ...
"rate-limiting-advanced": {
"rate-limit-exceeded": {
"fields": [
"consumer",
"ip",
"service",
"rate",
"limit",
"window"
],
"unique": [
"consumer",
"ip",
"service"
],
"description": "Run an event when a rate limit has been exceeded"
}
},
...
|
注册和验证 Event Hook#
如上例，source 为 rate-limiting-advanced，event 为 rate-limit-exceeded，可用参数有 consumer、ip 等。基于这些信息，先创建一个 webhook-custom 类型的 Event Hook：
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| curl -k -X POST 'http://localhost:31001/event-hooks' \
-H 'Kong-Admin-Token: kong' \
--data "source=rate-limiting-advanced" \
--data "event=rate-limit-exceeded" \
--data "handler=webhook-custom" \
--data "config.method=POST" \
--data "config.headers.content-type=application/json" \
--data "config.payload.text=Rate limit exceeded by username '{{ consumer.username }}' on service ' {{ service.name }}' (on server owned by $USER) " \
--data "config.url=https://hooks.slack.com/services/TTTTTTTTT/YYYYYYYYYYY/xxxxxxxxxxxxxxxxxx"
|
这样，当发生 Rate Limit 事件时，会向 Slack 频道发送如下消息：
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| Rate limit exceeded by username 'Joe' on service 'test' (on server owned by ubuntu)
|
注册 log 类型的 Event Hook 也很简单，只需将 handler 改为 log：
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| curl -k -X POST 'http://localhost:31001/event-hooks' \
-H 'Kong-Admin-Token: kong' \
--data "source=rate-limiting-advanced" \
--data "event=rate-limit-exceeded" \
--data "handler=log"
|
这样事件发生时会输出如下日志。需要将日志级别设置为 DEBUG。
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| 2022/11/21 04:27:36 [debug] 2120#0: *1338 [kong] event_hooks.lua:?:452 [core]--------------------------------------------------------------------------------------+
2022/11/21 04:27:36 [debug] 2120#0: *1338 |"log callback: " { "rate-limit-exceeded", "rate-limiting-advanced", { |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | consumer = {}, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | ip = "10.42.0.1", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | limit = 3, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | rate = 4, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | service = { |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | connect_timeout = 60000, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | created_at = 1668754239, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | enabled = true, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | host = "httpbin.org", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | id = "9d0bee90-04b9-4af3-993f-b10db881b144", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | name = "demo", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | path = "/anything", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | port = 80, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | protocol = "http", |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | read_timeout = 60000, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | retries = 5, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | updated_at = 1668754239, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | write_timeout = 60000, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | ws_id = "d06c2d4d-3fb1-49ae-a4c8-5806328c591d" |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | }, |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | window = "minute" |
2022/11/21 04:27:36 [debug] 2120#0: *1338 | }, 2120 } |
2022/11/21 04:27:36 [debug] 2120#0: *1338 +------------------------------------------------------------------------------------------------------------------------+
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Event Hooks 能实现的功能还有很多，今天就先到这里。如果你感兴趣，不妨试试看！