Istio 下 Envoy 配置举例#

大部分书籍和文档,都是按架构分层,自上而下(Top down) ,从概念、高层设计、基本原理、抽象流程去说明一个软件架构的。这个套路很学院派,也是非常稳重踏实的选择。但本节不采用这种方式。本节先举例分析一个具体场景下的现场分析。从具体和整体上,先让读者对设计有个感性的理解。再去分析为何要这样 “配置”,背后的抽象概念和基本原理。这样,可以让学习的人保持兴趣,也比较合符人类自然的,从具体中提炼出抽象的学习习惯。毕竟,笔者是个念过师范专业的人,虽然连个 “教师资格证” 也没拿到。

要理解 Istio 数据面基理,首先要看懂 sidecar proxy - Envoy 的配置。本节用一个例子,看看 istiod 写了什么 “代码” 去控制这个 “可编程代理” —— Envoy 。

实验环境#

本节的实验环境说明见于: 简单分层实验环境

架构图:

Inbound与Outbound概念

图:Istio 里的 Envoy 配置 - 部署#

用 Draw.io 打开

首先看看 Envoy 的配置:

kubectl exec fortio-server -c istio-proxy  -- \
curl 'localhost:15000/config_dump?include_eds' | \
yq eval -P > envoy@istio-conf-eg-inbound.envoy_conf.yaml

下面先不展开说明配置文件,直接看分析过程,最后,会回归到这个配置中。

Inbound 数据流 “推断”#

分析上面获取到的 Envoy 配置,可以 “推断” 到下面 Inbound 数据流图:

Inbound与Outbound概念

图:Istio里的 Envoy Inbound 配置举例#

用 Draw.io 打开

喜欢较真的程序员,对 “推断” 的事情有天然的不安感。那么,我们想法子 debug 一下,验证上图的可靠性。

用日志检查数据流#

  1. 开始前,先看看环境细节:

labile@labile-T30  labile $ k get pod netshoot -owide
NAME       READY   STATUS    RESTARTS   AGE   IP               NODE        NOMINATED NODE   READINESS GATES
netshoot   2/2     Running   11         8d    172.21.206.228   worknode5   <none>           <none>


labile@labile-T30  labile $ k get pod fortio-server -owide
NAME            READY   STATUS    RESTARTS   AGE   IP               NODE        NOMINATED NODE   READINESS GATES
fortio-server   2/2     Running   11         8d    172.21.206.230   worknode5   <none>           <none>


labile@labile-T30  labile $ k get svc fortio-server      
NAME            TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)                                        AGE
fortio-server   NodePort   10.96.215.136   <none>        8080:32463/TCP,8070:32265/TCP,8079:30167/TCP   8d


labile@labile-T30  labile $ k get endpoints fortio-server 
NAME            ENDPOINTS                                                     AGE
fortio-server   172.21.206.230:8079,172.21.206.230:8070,172.21.206.230:8080   8d
  1. 开一个专用 监控日志终端窗口,:

k logs -f fortio-server -c istio-proxy
  1. 看看客户端(netshoot) 到 fortio-server 的连接情况。发现未有连接,即到 fortio-server 的连接池未初始化。

$ k exec -it netshoot -- ss -tr

State Recv-Q Send-Q Local Address:Port                           Peer Address:Port Process
ESTAB 0      0          localhost:52012                             localhost:15020       
ESTAB 0      0          localhost:51978                             localhost:15020       
ESTAB 0      0           netshoot:53522 istiod.istio-system.svc.cluster.local:15012       
ESTAB 0      0           netshoot:42974 istiod.istio-system.svc.cluster.local:15012       
ESTAB 0      0          localhost:15020                             localhost:52012       
ESTAB 0      0          localhost:15020                             localhost:51978       

解释一下上面的命令。-t 是只看 tcp 连接。-r 是尝试对 ip 地址反向解释回域名。

小技巧

如果你的环境中发现已经有连接,那么,强制断开它。因为后面要分析一下建立新连接的日志。这里有个 强制断开连接的 ss 命令的秘技:

k exec -it netshoot -- ss -K 'dst 172-21-206-230.fortio-server.mark.svc.cluster.local'

其中 dst 172-21-206-230.fortio-server.mark.svc.cluster.local 是个过滤器条件,用于指定执行断开的连接。命令的意思是断开对端目标地址172-21-206-230.fortio-server.mark.svc.cluster.local 的连接。172-21-206-230.fortio-server.mark.svc.cluster.local就是 k8s 自动给这个 fortio-server POD 的域名了。

  1. 修改日志级别:

k exec fortio-server -c istio-proxy -- curl -XPOST http://localhost:15000/logging
k exec fortio-server -c istio-proxy -- curl -XPOST curl -XPOST 'http://localhost:15000/logging?level=debug'
  1. 在 k8s cluster 内发起请求:

sleep 5 && k exec -it netshoot -- curl -v http://fortio-server:8080/
  1. 查看连接

$ k exec -it netshoot -- ss -trn | grep fortio

State  Recv-Q  Send-Q     Local Address:Port                                             Peer Address:Port   Process  
...
ESTAB  0       0               netshoot:52352     172-21-206-230.fortio-server.mark.svc.cluster.local:8080            
...
  1. 查看日志 这时,在之前打开的 监控日志终端窗口 中,应该可以看到日志:

envoy filter	original_dst: new connection accepted
envoy filter	tls inspector: new connection accepted
envoy filter	tls:onServerName(), requestedServerName: outbound_.8080_._.fortio-server.mark.svc.cluster.local
envoy conn_handler	[C12990] new connection from 172.21.206.228:52352

envoy http	[C12990] new stream
envoy http	[C12990][S11192089021443921902] request headers complete (end_stream=true):
':authority', 'fortio-server:8080'
':path', '/'
':method', 'GET'
'user-agent', 'curl/7.83.1'
'accept', '*/*'
'x-forwarded-proto', 'http'
'x-request-id', '437a5a3e-f057-4079-a959-dad3d7dcf6a6'
'x-envoy-decorator-operation', 'fortio-server.mark.svc.cluster.local:8080/*'
'x-envoy-peer-metadata', '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'
'x-envoy-peer-metadata-id', 'sidecar~172.21.206.228~netshoot.mark~mark.svc.cluster.local'

'x-envoy-attempt-count', '1'
'x-b3-traceid', '03824b6065cd13e0559df95ebf18def7'
'x-b3-spanid', '559df95ebf18def7'
'x-b3-sampled', '0'


envoy http	[C12990][S11192089021443921902] request end stream
envoy connection	[C12990] current connecting state: false
envoy router	[C12990][S11192089021443921902] cluster 'inbound|8080||' match for URL '/'
envoy upstream	transport socket match, socket default selected for host with address 172.21.206.230:8080
envoy upstream	Created host 172.21.206.230:8080.
envoy upstream	addHost() adding 172.21.206.230:8080
envoy upstream	membership update for TLS cluster inbound|8080|| added 1 removed 0
envoy upstream	re-creating local LB for TLS cluster inbound|8080||
envoy upstream	membership update for TLS cluster inbound|8080|| added 1 removed 0
envoy upstream	re-creating local LB for TLS cluster inbound|8080||
envoy router	[C12990][S11192089021443921902] router decoding headers:
':authority', 'fortio-server:8080'
':path', '/'
':method', 'GET'
':scheme', 'http'
'user-agent', 'curl/7.83.1'
'accept', '*/*'
'x-forwarded-proto', 'http'
'x-request-id', '437a5a3e-f057-4079-a959-dad3d7dcf6a6'

'x-envoy-attempt-count', '1'
'x-b3-traceid', '03824b6065cd13e0559df95ebf18def7'
'x-b3-spanid', '559df95ebf18def7'
'x-b3-sampled', '0'
'x-forwarded-client-cert', 'By=spiffe://cluster.local/ns/mark/sa/default;Hash=a3c273eef68529003f564ff48b906ea61630a25217edbc18b57495701d089904;Subject="";URI=spiffe://cluster.local/ns/mark/sa/default'

envoy pool	queueing stream due to no available connections
envoy pool	trying to create new connection
envoy pool	creating a new connection
envoy connection	[C12991] current connecting state: true
envoy client	[C12991] connecting
envoy connection	[C12991] connecting to 172.21.206.230:8080
envoy connection	[C12991] connection in progress
envoy upstream	membership update for TLS cluster inbound|8080|| added 1 removed 0
envoy upstream	re-creating local LB for TLS cluster inbound|8080||
envoy connection	[C12991] connected
envoy client	[C12991] connected
envoy pool	[C12991] attaching to next stream
envoy pool	[C12991] creating stream
envoy router	[C12990][S11192089021443921902] pool ready
envoy client	[C12991] response complete
envoy router	[C12990][S11192089021443921902] upstream headers complete: end_stream=true
envoy http	[C12990][S11192089021443921902] encoding headers via codec (end_stream=true):
':status', '200'
'date', 'Sun, 28 Aug 2022 13:46:17 GMT'
'content-length', '0'
'x-envoy-upstream-service-time', '2'
'x-envoy-peer-metadata', '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'
'x-envoy-peer-metadata-id', 'sidecar~172.21.206.230~fortio-server.mark~mark.svc.cluster.local'
'server', 'istio-envoy'

envoy wasm	wasm log stats_inbound stats_inbound: [extensions/stats/plugin.cc:645]::report() metricKey cache hit , stat=12
envoy wasm	wasm log stats_inbound stats_inbound: [extensions/stats/plugin.cc:645]::report() metricKey cache hit , stat=6
envoy wasm	wasm log stats_inbound stats_inbound: [extensions/stats/plugin.cc:645]::report() metricKey cache hit , stat=10
envoy wasm	wasm log stats_inbound stats_inbound: [extensions/stats/plugin.cc:645]::report() metricKey cache hit , stat=14
envoy pool	[C12991] response complete
envoy pool	[C12991] destroying stream: 0 remaining

下图说明日志相关的组件与源码链接:

图:Istio里的 Envoy Inbound 组件与日志

图:Istio里的 Envoy Inbound 组件与日志#

用 Draw.io 打开

Outbound 数据流 “推断”#

分析上面获取到的 Envoy 配置,可以 “推断” 到下面 Outbound 数据流图:

图:Istio里的 Envoy Outbound 配置举例

图:Istio里的 Envoy Outbound 配置举例#

用 Draw.io 打开

用 bpftrace 检查数据流#

见我的 Blog: 逆向工程与云原生现场分析 Part3 —— eBPF 跟踪 Istio/Envoy 事件驱动模型、连接建立、TLS 握手与 filter_chain 选择