Traffic Management

参考

Traffic Managementとは

Argo Rolloutsでdeploy中の新version applicationへ流すtrafficの割合を制御できます。 getting-started の例でもある通り、defaultでは新version applicationと旧version applicationのService selecttorに紐付くReplicaSetのPod数を変動させることでtrafficの割合を制御します。 Argo Rolloutsの Traffic Management ではサービスメッシュ(AWS ALB Ingress Controller や Nginx Ingress Controller 含む) と連携することが可能です。

Traffic Managementは大きく3つの手法があります。

Raw percentages
- 新versionにN%、旧versionにN% といった割合で指定する
- ALB Ingress, Nginx Ingressも対応
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/nginx/nginx.go
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/alb/alb.go
Header-based routing
- 任意のheaderがリクエストに含まれている場合は新versionに流す
- ALB Ingress対応
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/nginx/nginx.go
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/alb/alb.go
Mirrored traffic
- まったく同じtrafficを新versionにも流す。ただし、responseは無視される
- ALB Ingress, Nginx Ingressも非対応
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/nginx/nginx.go
  - https://github.com/argoproj/argo-rollouts/blob/v1.4.0/rollout/trafficrouting/alb/alb.go

設定

ALBの場合

https://argoproj.github.io/argo-rollouts/features/traffic-management/alb/#usage

Rollout

spec.strategy.canary.canaryService
spec.strategy.canary.stableService

spec.strategy.canary.trafficRouting (ServiceMeshによってparameterが異なる)

spec:
  ...
  strategy:
    canary:
      canaryService: canary-service
      stableService: stable-service
      trafficRouting:
        alb:
          ingress: ingress
          servicePort: 443

Ingress

spec.rules 以下のruleが Rollout の spec.strategy.canary.stableService と一致するruleでdeployされる必要があります

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress
  annotations:
    kubernetes.io/ingress.class: alb
spec:
  rules:
  - http:
      paths:
      - path: /*
        backend:
          # serviceName must match either: canary.trafficRouting.alb.rootService (if specified),
          # or canary.stableService (if rootService is omitted)
          serviceName: stable-service
          # servicePort must be the value: use-annotation
          # This instructs AWS Load Balancer Controller to look to annotations on how to direct traffic
          servicePort: use-annotation

rolloutがdeploy中

ALB Controllerが理解できるJSON payloadを含む alb.ingress.kubernetes.io/actions.<SERVICE-NAME> annotationをRollouts ControllerがIngressリソースに注入します

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress
  annotations:
    kubernetes.io/ingress.class: alb
    alb.ingress.kubernetes.io/actions.stable-service: |
      {
        "Type":"forward",
        "ForwardConfig":{
          "TargetGroups":[
            {
                "Weight":10,
                "ServiceName":"canary-service",
                "ServicePort":"80"
            },
            {
                "Weight":90,
                "ServiceName":"stable-service",
                "ServicePort":"80"
            }
          ]
        }
      }
spec:
  rules:
  - http:
      paths:
      - path: /*
        backend:
          serviceName: stable-service
          servicePort: use-annotation