基本术语
- Downstream（下游）：下游主机连接到 Envoy，发送请求并接收响应，即发送请求的主机。
- Upstream（上游）：上游主机接收来自 Envoy 的连接和请求，并返回响应，即接受请求的主机。
- Listener（监听器）：监听器是命名网地址（例如，端口、unix domain socket 等)，下游客户端可以连接这些监听器。Envoy 暴露一个或者多个监听器给下游主机连接。
- Cluster（集群）：集群是指 Envoy 连接的一组逻辑相同的上游主机。Envoy 通过服务发现来发现集群的成员。可以选择通过主动健康检查来确定集群成员的健康状态。Envoy 通过负载均衡策略决定将请求路由到集群的哪个成员。
client ---> nginx(upstream)--->后端服务
对应envoy:
downstream(下游) ---> envoy ----->upstream(上游)
istio访问日志常见标识码
HTTP and TCP
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UH: No healthy upstream hosts in upstream cluster in addition to 503 response code.
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UF: Upstream connection failure in addition to 503 response code.
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UO: Upstream overflow (circuit breaking) in addition to 503 response code.
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NR: No route configured for a given request in addition to 404 response code.
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URX: The request was rejected because the upstream retry limit (HTTP) or maximum connect attempts (TCP) was reached.
HTTP only
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DC: Downstream connection termination.
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LH: Local service failed health check request in addition to 503 response code.
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UT: Upstream request timeout in addition to 504 response code.
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LR: Connection local reset in addition to 503 response code.
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UR: Upstream remote reset in addition to 503 response code.
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UC: Upstream connection termination in addition to 503 response code.
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DI: The request processing was delayed for a period specified via fault injection.
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FI: The request was aborted with a response code specified via fault injection.
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RL: The request was ratelimited locally by the HTTP rate limit filter in addition to 429 response code.
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UAEX: The request was denied by the external authorization service.
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RLSE: The request was rejected because there was an error in rate limit service.
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IH: The request was rejected because it set an invalid value for a strictly-checked header in addition to 400 response code.
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SI: Stream idle timeout in addition to 408 response code.
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DPE: The downstream request had an HTTP protocol error.