为什么需要灰度发布
灰度发布（又名金丝雀发布）是指在黑与白之间，能够平滑过渡的一种发布方式。在其上可以进行A/B testing，即让一部分用户继续用产品特性A，一部分用户开始用产品特性B，如果用户对B没有什么反对意见，那么逐步扩大范围，把所有用户都迁移到B上面来。
总结下一些应用场景：
- 微服务依赖很多组件，需要在实际环境验证
- 部署新功能有风险，然后可以通过导流一小部分用户实际使用，来减小风险
- 让特定的用户访问新版本，比如部署一个版本，只让测试使用
- A/B Testing，部署两个版本，进行版本对比，比如验证两个推荐服务的推荐效果
灰度发布可以保证整体系统的稳定，在初始灰度的时候就可以发现、调整问题，以保证其影响度。
ambassador介绍
ambassador[æmˈbæsədər]，是Kubernetes微服务 API gateway,基于Envoy Proxy。
官方地址：
部署ambassador
按官网提示部署ambassador
cat <<EOF | kubectl apply -f -
---
apiVersion: v1
kind: Service
metadata:
labels:
service: ambassador-admin
name: ambassador-admin
spec:
type: NodePort
ports:
- name: ambassador-admin
port: 8877
targetPort: 8877
selector:
service: ambassador
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
name: ambassador
rules:
- apiGroups: [""]
resources: [ "endpoints", "namespaces", "secrets", "services" ]
verbs: ["get", "list", "watch"]
- apiGroups: [ "getambassador.io" ]
resources: [ "*" ]
verbs: ["get", "list", "watch"]
- apiGroups: [ "apiextensions.k8s.io" ]
resources: [ "customresourcedefinitions" ]
verbs: ["get", "list", "watch"]
- apiGroups: [ "networking.internal.knative.dev" ]
resources: [ "clusteringresses", "ingresses" ]
verbs: ["get", "list", "watch"]
- apiGroups: [ "networking.internal.knative.dev" ]
resources: [ "ingresses/status", "clusteringresses/status" ]
verbs: ["update"]
- apiGroups: [ "extensions" ]
resources: [ "ingresses" ]
verbs: ["get", "list", "watch"]
- apiGroups: [ "extensions" ]
resources: [ "ingresses/status" ]
verbs: ["update"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: ambassador
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: ambassador
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: ambassador
subjects:
- kind: ServiceAccount
name: ambassador
namespace: kube-system
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: authservices.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: authservices
singular: authservice
kind: AuthService
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: consulresolvers.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: consulresolvers
singular: consulresolver
kind: ConsulResolver
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: kubernetesendpointresolvers.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: kubernetesendpointresolvers
singular: kubernetesendpointresolver
kind: KubernetesEndpointResolver
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: kubernetesserviceresolvers.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: kubernetesserviceresolvers
singular: kubernetesserviceresolver
kind: KubernetesServiceResolver
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: mappings.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: mappings
singular: mapping
kind: Mapping
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: modules.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: modules
singular: module
kind: Module
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: ratelimitservices.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: ratelimitservices
singular: ratelimitservice
kind: RateLimitService
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: tcpmappings.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: tcpmappings
singular: tcpmapping
kind: TCPMapping
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: tlscontexts.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: tlscontexts
singular: tlscontext
kind: TLSContext
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: tracingservices.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: tracingservices
singular: tracingservice
kind: TracingService
categories:
- ambassador-crds
---
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: logservices.getambassador.io
spec:
group: getambassador.io
version: v1
versions:
- name: v1
served: true
storage: true
scope: Namespaced
names:
plural: logservices
singular: logservice
kind: LogService
categories:
- ambassador-crds
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: ambassador
spec:
replicas: 3
selector:
matchLabels:
service: ambassador
template:
metadata:
annotations:
sidecar.istio.io/inject: "false"
"consul.hashicorp.com/connect-inject": "false"
labels:
service: ambassador
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchLabels:
service: ambassador
topologyKey: kubernetes.io/hostname
serviceAccountName: ambassador
containers:
- name: ambassador
image: quay.azk8s.cn/datawire/ambassador:0.86.1
resources:
limits:
cpu: 1
memory: 400Mi
requests:
cpu: 200m
memory: 100Mi
env:
- name: AMBASSADOR_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
ports:
- name: http
containerPort: 8080
- name: https
containerPort: 8443
- name: admin
containerPort: 8877
livenessProbe:
httpGet:
path: /ambassador/v0/check_alive
port: 8877
initialDelaySeconds: 30
periodSeconds: 3
readinessProbe:
httpGet:
path: /ambassador/v0/check_ready
port: 8877
initialDelaySeconds: 30
periodSeconds: 3
volumeMounts:
- name: ambassador-pod-info
mountPath: /tmp/ambassador-pod-info
volumes:
- name: ambassador-pod-info
downwardAPI:
items:
- path: "labels"
fieldRef:
fieldPath: metadata.labels
restartPolicy: Always
securityContext:
runAsUser: 8888
---
apiVersion: v1
kind: Service
metadata:
name: ambassador
spec:
type: NodePort
externalTrafficPolicy: Local
ports:
- port: 80
targetPort: 8080
selector:
service: ambassador
EOF
为了方便访问网关，生成一个ingress：
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
annotations:
nginx.ingress.kubernetes.io/proxy-body-size: "0"
nginx.ingress.kubernetes.io/proxy-read-timeout: "600"
nginx.ingress.kubernetes.io/proxy-send-timeout: "600"
kubernetes.io/tls-acme: 'true'
name: ambassador
spec:
rules:
- host: ambassador.iflyresearch.com
http:
paths:
- backend:
serviceName: ambassador
servicePort: 80
path: /
ambassador 配置
ambassador 使用envoy来实现相关的负载，而envoy类似nginx。ambassador的原理大概是读取service里的配置，然后自动生成envoy的配置，当service变更时，动态更新envoy的配置并重启，所以ambassador需要可以访问服务API。
ambassador 的配置是放到metadata的annotations,以getambassador.io/config开头：
annotations:
getambassador.io/config: |
---
apiVersion: ambassador/v0
kind: Mapping
name: {{ .Values.service.name }}_mapping
prefix: /{{ .Values.service.prefix }}
service: {{ .Values.service.name }}.{{ .Release.Namespace }}
profix指定如何访问服务，service指定指向那个服务。注意，需要加上namespace名称，否则容易报找不到后端。
ambassador 灰度
ambassador实现灰度可以根据weight权重，或者指定匹配特定的header来实现。
根据weight进行灰度
用法：
部署一个新版本的service，prefix和之前老服务保持一致，但是配置weight，比如20，这样20%的流量会流转到新服务，这样实现A/B Test
---
apiVersion: v1
kind: Service
metadata:
name: svc-gray
namespace: default
annotations:
getambassador.io/config: |
---
apiVersion: ambassador/v0
kind: Mapping
name: svc1_mapping
prefix: /svc/
service: service-gray
weight: 20
spec:
selector:
app: testservice
ports:
- port: 8080
name: service-gray
targetPort: http-api
根据请求头 header 进行灰度 (regex_headers 正则匹配)
部署一个新版本，只需要特定的用户才能访问，可以通过该方案来实现。
例如：
---
apiVersion: v1
kind: Service
metadata:
name: svc-gray
namespace: default
annotations:
getambassador.io/config: |
---
apiVersion: ambassador/v0
kind: Mapping
name: svc1_mapping
prefix: /svc/
service: service-gray
headers:
gray: true
spec:
selector:
app: testservice
ports:
- port: 8080
name: service-gray
targetPort: http-api
访问时，当指定gray: true时，访问灰度版本，可以用postman来测试：