镜像

此任务演示了 Istio 的流量镜像功能。

流量镜像,也称为影子流量,是一个以尽可能低的风险为生产带来变化的强大的功能。镜像会将实时流量的副本发送到镜像服务。镜像流量发生在主服务的关键请求路径之外。

在此任务中,首先把所有流量路由到 v1 测试服务。然后使用规则将一部分流量镜像到 v2

开始之前

  • 按照安装指南中的说明设置 Istio。

  • 首先部署启用了访问日志的两个版本的 httpbin 服务:

httpbin-v1:

  1. $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
  2. apiVersion: extensions/v1beta1
  3. kind: Deployment
  4. metadata:
  5. name: httpbin-v1
  6. spec:
  7. replicas: 1
  8. template:
  9. metadata:
  10. labels:
  11. app: httpbin
  12. version: v1
  13. spec:
  14. containers:
  15. - image: docker.io/kennethreitz/httpbin
  16. imagePullPolicy: IfNotPresent
  17. name: httpbin
  18. command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
  19. ports:
  20. - containerPort: 80
  21. EOF

httpbin-v2:

  1. $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
  2. apiVersion: extensions/v1beta1
  3. kind: Deployment
  4. metadata:
  5. name: httpbin-v2
  6. spec:
  7. replicas: 1
  8. template:
  9. metadata:
  10. labels:
  11. app: httpbin
  12. version: v2
  13. spec:
  14. containers:
  15. - image: docker.io/kennethreitz/httpbin
  16. imagePullPolicy: IfNotPresent
  17. name: httpbin
  18. command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
  19. ports:
  20. - containerPort: 80
  21. EOF

httpbin Kubernetes service:

  1. $ kubectl create -f - <<EOF
  2. apiVersion: v1
  3. kind: Service
  4. metadata:
  5. name: httpbin
  6. labels:
  7. app: httpbin
  8. spec:
  9. ports:
  10. - name: http
  11. port: 8000
  12. targetPort: 80
  13. selector:
  14. app: httpbin
  15. EOF
  • 启动 sleep 服务,这样就可以使用 curl 来提供负载了:

sleep service:

  1. $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
  2. apiVersion: extensions/v1beta1
  3. kind: Deployment
  4. metadata:
  5. name: sleep
  6. spec:
  7. replicas: 1
  8. template:
  9. metadata:
  10. labels:
  11. app: sleep
  12. spec:
  13. containers:
  14. - name: sleep
  15. image: tutum/curl
  16. command: ["/bin/sleep","infinity"]
  17. imagePullPolicy: IfNotPresent
  18. EOF

创建默认路由策略

默认情况下,Kubernetes 在 httpbin 服务的两个版本之间进行负载均衡。在此步骤中会更改该行为,把所有流量都路由到 v1

  • 创建一个默认路由规则,将所有流量路由到服务的 v1

如果为 Istio 启用了双向 TLS 认证,在应用前必须将 TLS 流量策略 mode: ISTIO_MUTUAL 添加到 DestinationRule。否则,请求将发生 503 错误,如设置目标规则后出现 503 错误所述。

  1. $ kubectl apply -f - <<EOF
  2. apiVersion: networking.istio.io/v1alpha3
  3. kind: VirtualService
  4. metadata:
  5. name: httpbin
  6. spec:
  7. hosts:
  8. - httpbin
  9. http:
  10. - route:
  11. - destination:
  12. host: httpbin
  13. subset: v1
  14. weight: 100
  15. ---
  16. apiVersion: networking.istio.io/v1alpha3
  17. kind: DestinationRule
  18. metadata:
  19. name: httpbin
  20. spec:
  21. host: httpbin
  22. subsets:
  23. - name: v1
  24. labels:
  25. version: v1
  26. - name: v2
  27. labels:
  28. version: v2
  29. EOF

现在所有流量已经都转到 httpbin:v1 服务。

  • 向服务发送一些流量:
  1. $ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
  2. $ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8000/headers' | python -m json.tool
  3. {
  4. "headers": {
  5. "Accept": "*/*",
  6. "Content-Length": "0",
  7. "Host": "httpbin:8000",
  8. "User-Agent": "curl/7.35.0",
  9. "X-B3-Sampled": "1",
  10. "X-B3-Spanid": "eca3d7ed8f2e6a0a",
  11. "X-B3-Traceid": "eca3d7ed8f2e6a0a",
  12. "X-Ot-Span-Context": "eca3d7ed8f2e6a0a;eca3d7ed8f2e6a0a;0000000000000000"
  13. }
  14. }
  • 查看 httpbin pods 的 v1v2 日志。您可以看到 v1 的访问日志和 v2<none> 的日志:
  1. $ export V1_POD=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..metadata.name})
  2. $ kubectl logs -f $V1_POD -c httpbin
  3. 127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
  1. $ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name})
  2. $ kubectl logs -f $V2_POD -c httpbin
  3. <none>

镜像流量到 v2

  • 改变路由规则将流量镜像到 v2:
  1. $ kubectl apply -f - <<EOF
  2. apiVersion: networking.istio.io/v1alpha3
  3. kind: VirtualService
  4. metadata:
  5. name: httpbin
  6. spec:
  7. hosts:
  8. - httpbin
  9. http:
  10. - route:
  11. - destination:
  12. host: httpbin
  13. subset: v1
  14. weight: 100
  15. mirror:
  16. host: httpbin
  17. subset: v2
  18. EOF

此路由规则将 100% 的流量发送到 v1 。最后一节指定镜像到 httpbin:v2 服务。当流量被镜像时,请求将通过其主机/授权报头发送到镜像服务附上 -shadow。例如,将 cluster-1 变为 cluster-1-shadow

此外,重点注意这些被镜像的请求是“即发即弃”的,也就是说这些请求引发的响应是会被丢弃的。

  • 发送流量:
  1. $ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8000/headers' | python -m json.tool

这样就可以看到 v1v2 中都有了访问日志。v2 中的访问日志就是由镜像流量产生的,这些请求的实际目标是 v1

  1. $ kubectl logs -f $V1_POD -c httpbin
  2. 127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
  3. 127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
  1. $ kubectl logs -f $V2_POD -c httpbin
  2. 127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 361 "-" "curl/7.35.0"
  • 如果要检查流量内部,请在另一个控制台上运行以下命令:
  1. $ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
  2. $ export V1_POD_IP=$(kubectl get pod -l app=httpbin -l version=v1 -o jsonpath={.items..status.podIP})
  3. $ export V2_POD_IP=$(kubectl get pod -l app=httpbin -l version=v2 -o jsonpath={.items..status.podIP})
  4. $ kubectl exec -it $SLEEP_POD -c istio-proxy -- sudo tcpdump -A -s 0 host $V1_POD_IP or host $V2_POD_IP
  5. tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
  6. listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
  7. 05:47:50.159513 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [P.], seq 4039989036:4039989832, ack 3139734980, win 254, options [nop,nop,TS val 77427918 ecr 76730809], length 796: HTTP: GET /headers HTTP/1.1
  8. E..P2.X.X.X.
  9. .K.
  10. .K....P..W,.$.......+.....
  11. ..t.....GET /headers HTTP/1.1
  12. host: httpbin:8000
  13. user-agent: curl/7.35.0
  14. accept: */*
  15. x-forwarded-proto: http
  16. x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
  17. x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
  18. x-b3-traceid: 82f3e0a76dcebca2
  19. x-b3-spanid: 82f3e0a76dcebca2
  20. x-b3-sampled: 0
  21. x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
  22. content-length: 0
  23. 05:47:50.159609 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [P.], seq 296287713:296288571, ack 4029574162, win 254, options [nop,nop,TS val 77427918 ecr 76732809], length 858: HTTP: GET /headers HTTP/1.1
  24. E.....X.X...
  25. .K.
  26. .G....P......l......e.....
  27. ..t.....GET /headers HTTP/1.1
  28. host: httpbin-shadow:8000
  29. user-agent: curl/7.35.0
  30. accept: */*
  31. x-forwarded-proto: http
  32. x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
  33. x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
  34. x-b3-traceid: 82f3e0a76dcebca2
  35. x-b3-spanid: 82f3e0a76dcebca2
  36. x-b3-sampled: 0
  37. x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
  38. x-envoy-internal: true
  39. x-forwarded-for: 10.233.75.12
  40. content-length: 0
  41. 05:47:50.166734 IP 10-233-75-11.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.38836: Flags [P.], seq 1:472, ack 796, win 276, options [nop,nop,TS val 77427925 ecr 77427918], length 471: HTTP: HTTP/1.1 200 OK
  42. E....3X.?...
  43. .K.
  44. .K..P...$....ZH...........
  45. ..t...t.HTTP/1.1 200 OK
  46. server: envoy
  47. date: Fri, 15 Feb 2019 05:47:50 GMT
  48. content-type: application/json
  49. content-length: 241
  50. access-control-allow-origin: *
  51. access-control-allow-credentials: true
  52. x-envoy-upstream-service-time: 3
  53. {
  54. "headers": {
  55. "Accept": "*/*",
  56. "Content-Length": "0",
  57. "Host": "httpbin:8000",
  58. "User-Agent": "curl/7.35.0",
  59. "X-B3-Sampled": "0",
  60. "X-B3-Spanid": "82f3e0a76dcebca2",
  61. "X-B3-Traceid": "82f3e0a76dcebca2"
  62. }
  63. }
  64. 05:47:50.166789 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [.], ack 472, win 262, options [nop,nop,TS val 77427925 ecr 77427925], length 0
  65. E..42.X.X.\.
  66. .K.
  67. .K....P..ZH.$.............
  68. ..t...t.
  69. 05:47:50.167234 IP 10-233-71-7.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.49560: Flags [P.], seq 1:512, ack 858, win 280, options [nop,nop,TS val 77429926 ecr 77427918], length 511: HTTP: HTTP/1.1 200 OK
  70. E..3..X.>...
  71. .G.
  72. .K..P....l....;...........
  73. ..|...t.HTTP/1.1 200 OK
  74. server: envoy
  75. date: Fri, 15 Feb 2019 05:47:49 GMT
  76. content-type: application/json
  77. content-length: 281
  78. access-control-allow-origin: *
  79. access-control-allow-credentials: true
  80. x-envoy-upstream-service-time: 3
  81. {
  82. "headers": {
  83. "Accept": "*/*",
  84. "Content-Length": "0",
  85. "Host": "httpbin-shadow:8000",
  86. "User-Agent": "curl/7.35.0",
  87. "X-B3-Sampled": "0",
  88. "X-B3-Spanid": "82f3e0a76dcebca2",
  89. "X-B3-Traceid": "82f3e0a76dcebca2",
  90. "X-Envoy-Internal": "true"
  91. }
  92. }
  93. 05:47:50.167253 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [.], ack 512, win 262, options [nop,nop,TS val 77427926 ecr 77429926], length 0
  94. E..4..X.X...
  95. .K.
  96. .G....P...;..n............
  97. ..t...|.

您可以查看流量​​的请求和响应内容。

清理

  • 删除规则:
  1. $ kubectl delete virtualservice httpbin
  2. $ kubectl delete destinationrule httpbin
  • 关闭 httpbin 服务和客户端:
  1. $ kubectl delete deploy httpbin-v1 httpbin-v2 sleep
  2. $ kubectl delete svc httpbin