在Kubernetes上搭建RabbitMQ Cluster

文章目录

[隐藏]

• 1. IP模式
• 2. Pod与Service的DNS
• 3. Statefulset 与Headless Service
• 4. hostname模式

为了在Kubernetes上搭建RabbitMQ3.7.X Cluster，踩爆无数坑，官方整合了第三方开源项目但没有完整demo，网上的post都是RabbitMQ 3.6.X旧版的部署方案，几经周折，最终弄明白在Kubernetes集群下，基于Kubernetes Discovery，使用hostname方式部署RabbitMQ3.7.X Cluster，总结如下：

1. IP模式

rabbitmq-peer-discovery-k8s是RabbitMQ官方基于第三方开源项目rabbitmq-autocluster开发，对3.7.X版本提供的Kubernetes下的同行发现插件，但官方只提供了一个基于IP模式的demo

kind: Service  apiVersion: v1  metadata:    namespace: test-rabbitmq    name: rabbitmq    labels:      app: rabbitmq      type: LoadBalancer  spec:    type: NodePort    ports:     - name: http       protocol: TCP       port: 15672       targetPort: 15672       nodePort: 31672     - name: amqp       protocol: TCP       port: 5672       targetPort: 5672       nodePort: 30672    selector:      app: rabbitmq  ---  apiVersion: v1  kind: ConfigMap  metadata:    name: rabbitmq-config    namespace: test-rabbitmq  data:    enabled_plugins: |        [rabbitmq_management,rabbitmq_peer_discovery_k8s].    rabbitmq.conf: |        ## Cluster formation. See http://www.rabbitmq.com/cluster-formation.html to learn more.        cluster_formation.peer_discovery_backend  = rabbit_peer_discovery_k8s        cluster_formation.k8s.host = kubernetes.default.svc.cluster.local        ## Should RabbitMQ node name be computed from the pod's hostname or IP address?        ## IP addresses are not stable, so using [stable] hostnames is recommended when possible.        ## Set to "hostname" to use pod hostnames.        ## When this value is changed, so should the variable used to set the RABBITMQ_NODENAME        ## environment variable.        cluster_formation.k8s.address_type = ip        ## How often should node cleanup checks run?        cluster_formation.node_cleanup.interval = 30        ## Set to false if automatic removal of unknown/absent nodes        ## is desired. This can be dangerous, see        ##  * http://www.rabbitmq.com/cluster-formation.html#node-health-checks-and-cleanup        ##  * https://groups.google.com/forum/#!msg/rabbitmq-users/wuOfzEywHXo/k8z_HWIkBgAJ        cluster_formation.node_cleanup.only_log_warning = true        cluster_partition_handling = autoheal        ## See http://www.rabbitmq.com/ha.html#master-migration-data-locality        queue_master_locator=min-masters        ## See http://www.rabbitmq.com/access-control.html#loopback-users        loopback_users.guest = false    ---  apiVersion: apps/v1beta1  kind: StatefulSet  metadata:    name: rabbitmq    namespace: test-rabbitmq  spec:    serviceName: rabbitmq    replicas: 3    template:      metadata:        labels:          app: rabbitmq      spec:        serviceAccountName: rabbitmq        terminationGracePeriodSeconds: 10        containers:        - name: rabbitmq-k8s          image: rabbitmq:3.7          volumeMounts:            - name: config-volume              mountPath: /etc/rabbitmq          ports:            - name: http              protocol: TCP              containerPort: 15672            - name: amqp              protocol: TCP              containerPort: 5672          livenessProbe:            exec:              command: ["rabbitmqctl", "status"]            initialDelaySeconds: 60            periodSeconds: 60            timeoutSeconds: 10          readinessProbe:            exec:              command: ["rabbitmqctl", "status"]            initialDelaySeconds: 20            periodSeconds: 60            timeoutSeconds: 10          imagePullPolicy: Always          env:            - name: MY_POD_IP              valueFrom:                fieldRef:                  fieldPath: status.podIP            - name: RABBITMQ_USE_LONGNAME              value: "true"            # See a note on cluster_formation.k8s.address_type in the config file section            - name: RABBITMQ_NODENAME              value: "rabbit@$(MY_POD_IP)"            - name: K8S_SERVICE_NAME              value: "rabbitmq"            - name: RABBITMQ_ERLANG_COOKIE              value: "mycookie"        volumes:          - name: config-volume            configMap:              name: rabbitmq-config              items:              - key: rabbitmq.conf                path: rabbitmq.conf              - key: enabled_plugins                path: enabled_plugins  

在ConfigMap配置项中，指明 cluster_formation.k8s.address_type = ip，也就是说RabbitMQ Node的命名和访问地址是以IP地址作为区分，如[email protected]

但这样的配置会产生比较大的问题，如果我们使用pv和pvc去做数据的持久化，那么每个节点的配置和数据存储都会放在[email protected]这样的文件夹下，而Kubernetes集群中，Pod的IP都是不稳定的，当有RabbitMQ Node的Pod挂掉后，重新创建的Pod IP可能会变，这就会使得节点的配置和数据全部丢失。

所以我们更希望RabbitMQ Node的命名是以一定规则编写的相对稳定的名称，如[email protected]，这就需要修改 cluster_formation.k8s.address_type = hostname，以启用hostname模式。

但直接修改address_type 并不能满足要求，注释部分也描述了“Set to hostname to use pod hostnames. When this value is changed, so should the variable used to set the RABBITMQ_NODENAME”。那么RABBITMQ_NODENAME该如何设置，就必须先要了解如何用hostname访问pod

2. Pod与Service的DNS

Kubernetes官方讲述了如何用hostname访问service和pod：https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/

其中对于service，可以直接使用my-svc.my-namespace.svc.cluster.local进行访问；而对于pod，则需使用pod-ip-address.my-namespace.pod.cluster.local进行访问，但这里却仍显式的应用到了pod的ip。我们希望脱离ip对pod进行访问，很不幸的是，pod确实无法直接通过hostname访问，不过却有个曲线救国的方案。

apiVersion: v1  kind: Service  metadata:    name: default-subdomain # 和pod的subdomain相同  spec:    selector:      name: busybox    clusterIP: None  # clusterIP: None表示这是一个headless service    ports:    - name: foo # 没啥用      port: 1234      targetPort: 1234  ---  apiVersion: v1  kind: Pod  metadata:    name: busybox1    labels:      name: busybox  spec:    hostname: busybox-1 # 默认使用metadata.name作为hostname，也可指定设置    subdomain: default-subdomain    containers:    - image: busybox      command:        - sleep        - "3600"      name: busybox  

如上面代码所示，我们需要一个headless service来作为中介，这样就可以使用busybox-1.default-subdomain.default.svc.cluster.local来访问pod了（hostname.subdomain.my-namespace.svc.cluster.local）

3. Statefulset 与Headless Service

了解了如何用hostname访问Pod还不足以解决问题，在RabbitMQ的配置中，我们使用的是StatefulSet，那么StatefulSet如何用Headless Service去做Pod的hostname访问呢？

Kubernetes（StatefulSets在1.9版本后已经是一个稳定功能）官方也给出了详细的说明：https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/

Demo和注释如下：

apiVersion: v1  kind: Service  metadata:    name: nginx    labels:      app: nginx  spec:    ports:    - port: 80      name: web    clusterIP: None # 是一个headless service    selector:      app: nginx  ---  apiVersion: apps/v1 # 需要注意如果是apps/v1，.spec.selector.matchLabels和.spec.template.metadata.labels要相同；如果是apps/v1beta，可以省略.spec.selector.matchLabels  kind: StatefulSet  metadata:    name: web  spec:    selector:      matchLabels:        app: nginx # 需要与 .spec.template.metadata.labels 相同，但无需与headless service name相同    serviceName: "nginx" # 需要与headless service name相同    replicas: 3    template:      metadata:        labels:          app: nginx #  需要与 .spec.selector.matchLabels 相同，但无需与headless service name相同      spec:        terminationGracePeriodSeconds: 10        containers:        - name: nginx          image: k8s.gcr.io/nginx-slim:0.8          ports:          - containerPort: 80            name: web  

需要特别注意的是，网上很多例子的StatefulSet用的apps/v1beta

4. hostname模式

在我查找的众多资料中，在Kubernetes中

讲RabbitMQ 3.6.X部署的，www.kubernetes.org.cn/2629.html 这篇讲的比较清楚

讲RabbitMQ 3.7.X部署的，https://habr.com/company/eastbanctech/blog/419817/ 这篇俄文的Post讲的比较清楚，但它也是用的apps/v1beta，同时有大量的重复配置，不知道哪些可用哪些无用，还有一个最致命的问题是按照它的配置部署后，readinessProbe老报错，说DNS解析出现问题。几经折腾，才明白因为用Headless Service去做Pod的hostname访问，需要等Pod和Service都启动后才能访问，而readiness探针还没等DNS正常就去探查服务是否可用，所以才会误认为服务不可达，最终无法启动Pod。解决办法是给Headless Service设置publishNotReadyAddresses: true

我的配置文件如下所示：

apiVersion: v1  kind: Namespace  metadata:    name: rabbitmq  ---  apiVersion: v1  kind: ServiceAccount  metadata:    name: rabbitmq    namespace: rabbitmq  ---  kind: Role  apiVersion: rbac.authorization.k8s.io/v1beta1  metadata:    name: endpoint-reader    namespace: rabbitmq  rules:  - apiGroups: [""]    resources: ["endpoints"]    verbs: ["get"]  ---  kind: RoleBinding  apiVersion: rbac.authorization.k8s.io/v1beta1  metadata:    name: endpoint-reader    namespace: rabbitmq  subjects:  - kind: ServiceAccount    name: rabbitmq  roleRef:    apiGroup: rbac.authorization.k8s.io    kind: Role    name: endpoint-reader  ---  apiVersion: v1  kind: PersistentVolume  metadata:      name: rabbitmq-data      labels:        release: rabbitmq-data      namespace: rabbitmq  spec:      capacity:        storage: 10Gi      accessModes:        - ReadWriteMany      persistentVolumeReclaimPolicy: Retain      nfs:        path: /rabbit        server: xxxxx  # nas地址  ---  apiVersion: v1  kind: PersistentVolumeClaim  metadata:    name: rabbitmq-data-claim    namespace: rabbitmq  spec:    accessModes:      - ReadWriteMany    resources:      requests:        storage: 10Gi    selector:      matchLabels:        release: rabbitmq-data  ---  # headless service 用于使用hostname访问pod  kind: Service  apiVersion: v1  metadata:    name: rabbitmq-headless    namespace: rabbitmq  spec:    clusterIP: None    # publishNotReadyAddresses, when set to true, indicates that DNS implementations must publish the notReadyAddresses of subsets for the Endpoints associated with the Service. The default value is false. The primary use case for setting this field is to use a StatefulSet's Headless Service to propagate SRV records for its Pods without respect to their readiness for purpose of peer discovery. This field will replace the service.alpha.kubernetes.io/tolerate-unready-endpoints when that annotation is deprecated and all clients have been converted to use this field.    # 由于使用DNS访问Pod需Pod和Headless service启动之后才能访问，publishNotReadyAddresses设置成true，防止readinessProbe在服务没启动时找不到DNS    publishNotReadyAddresses: true    ports:     - name: amqp       port: 5672     - name: http       port: 15672    selector:      app: rabbitmq  ---  # 用于暴露dashboard到外网  kind: Service  apiVersion: v1  metadata:    namespace: rabbitmq    name: rabbitmq-service  spec:    type: NodePort    ports:     - name: http       protocol: TCP       port: 15672       targetPort: 15672       nodePort: 15672   # 注意k8s默认情况下，nodeport要在30000~32767之间，可以自行修改     - name: amqp       protocol: TCP       port: 5672       targetPort: 5672  # 注意如果你想在外网下访问mq，需要增配nodeport    selector:      app: rabbitmq  ---  apiVersion: v1  kind: ConfigMap  metadata:    name: rabbitmq-config    namespace: rabbitmq  data:    enabled_plugins: |        [rabbitmq_management,rabbitmq_peer_discovery_k8s].    rabbitmq.conf: |        cluster_formation.peer_discovery_backend  = rabbit_peer_discovery_k8s        cluster_formation.k8s.host = kubernetes.default.svc.cluster.local        cluster_formation.k8s.address_type = hostname        cluster_formation.node_cleanup.interval = 10        cluster_formation.node_cleanup.only_log_warning = true        cluster_partition_handling = autoheal        queue_master_locator=min-masters        loopback_users.guest = false  ​        cluster_formation.randomized_startup_delay_range.min = 0        cluster_formation.randomized_startup_delay_range.max = 2        # 必须设置service_name，否则Pod无法正常启动，这里设置后可以不设置statefulset下env中的K8S_SERVICE_NAME变量        cluster_formation.k8s.service_name = rabbitmq-headless        # 必须设置hostname_suffix，否则节点不能成为集群        cluster_formation.k8s.hostname_suffix = .rabbitmq-headless.rabbitmq.svc.cluster.local        # 内存上限        vm_memory_high_watermark.absolute = 1.6GB        # 硬盘上限        disk_free_limit.absolute = 2GB  ---  # 使用apps/v1版本代替apps/v1beta  apiVersion: apps/v1  kind: StatefulSet  metadata:    name: rabbitmq    namespace: rabbitmq  spec:    serviceName: rabbitmq-headless   # 必须与headless service的name相同，用于hostname传播访问pod    selector:      matchLabels:        app: rabbitmq # 在apps/v1中，需与 .spec.template.metadata.label 相同，用于hostname传播访问pod，而在apps/v1beta中无需这样做    replicas: 3    template:      metadata:        labels:          app: rabbitmq  # 在apps/v1中，需与 .spec.selector.matchLabels 相同        # 设置podAntiAffinity        annotations:          scheduler.alpha.kubernetes.io/affinity: >              {                "podAntiAffinity": {                  "requiredDuringSchedulingIgnoredDuringExecution": [{                    "labelSelector": {                      "matchExpressions": [{                        "key": "app",                        "operator": "In",                        "values": ["rabbitmq"]                      }]                    },                    "topologyKey": "kubernetes.io/hostname"                  }]                }              }      spec:        serviceAccountName: rabbitmq        terminationGracePeriodSeconds: 10        containers:        - name: rabbitmq          image: registry-vpc.cn-shenzhen.aliyuncs.com/heygears/rabbitmq:3.7          resources:            limits:              cpu: 0.5              memory: 2Gi            requests:              cpu: 0.3              memory: 2Gi          volumeMounts:            - name: config-volume              mountPath: /etc/rabbitmq            - name: rabbitmq-data              mountPath: /var/lib/rabbitmq/mnesia          ports:            - name: http              protocol: TCP              containerPort: 15672            - name: amqp              protocol: TCP              containerPort: 5672          livenessProbe:            exec:              command: ["rabbitmqctl", "status"]            initialDelaySeconds: 60            periodSeconds: 60            timeoutSeconds: 5          readinessProbe:            exec:              command: ["rabbitmqctl", "status"]            initialDelaySeconds: 20            periodSeconds: 60            timeoutSeconds: 5          imagePullPolicy: Always          env:            - name: HOSTNAME              valueFrom:                fieldRef:                  fieldPath: metadata.name            - name: RABBITMQ_USE_LONGNAME              value: "true"            - name: RABBITMQ_NODENAME              value: "rabbit@$(HOSTNAME).rabbitmq-headless.rabbitmq.svc.cluster.local"            # 若在ConfigMap中设置了service_name，则此处无需再次设置            # - name: K8S_SERVICE_NAME            #   value: "rabbitmq-headless"            - name: RABBITMQ_ERLANG_COOKIE              value: "mycookie"        volumes:          - name: config-volume            configMap:              name: rabbitmq-config              items:              - key: rabbitmq.conf                path: rabbitmq.conf              - key: enabled_plugins                path: enabled_plugins          - name: rabbitmq-data            persistentVolumeClaim:              claimName: rabbitmq-data-claim  

至此，终于在Kubernetes上部署完成RabbitMQ Cluster 3.7.X

原文出处：juejin -> https://juejin.im/entry/5bcd75f7f265da0a9223e8a2