NATS Streaming Cluster with FT Mode

Preparation
First, we need a Kubernetes cluster with a provider that offers a service with a ReadWriteMany filesystem available. In this short guide, we will create the cluster on AWS and then use EFS for the filesystem:
# Create 3 nodes Kubernetes cluster
eksctl create cluster --name nats-eks-cluster \
  --nodes 3 \
  --node-type=t3.large \
  --region=us-east-2
​
# Get the credentials for your cluster
eksctl utils write-kubeconfig --name nats-eks-cluster --region us-east-2
For the FT mode to work, we will need to create an EFS volume which can be shared by more than one pod. Go into the AWS console and create one and make the sure that it is in a security group where the k8s nodes will have access to it. In case of clusters created via eksctl, this will be a security group named ClusterSharedNodeSecurityGroup:
Screen Shot 2019-12-04 at 11 25 08 AM
Screen Shot 2019-12-04 at 12 40 13 PM
Creating the EFS provisioner
Confirm from the FilesystemID from the cluster and the DNS name, we will use those values to create an EFS provisioner controller within the K8S cluster:
Screen Shot 2019-12-04 at 12 08 35 PM
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: efs-provisioner
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: efs-provisioner-runner
rules:
  - apiGroups: [""]
    resources: ["persistentvolumes"]
    verbs: ["get", "list", "watch", "create", "delete"]
  - apiGroups: [""]
    resources: ["persistentvolumeclaims"]
    verbs: ["get", "list", "watch", "update"]
  - apiGroups: ["storage.k8s.io"]
    resources: ["storageclasses"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create", "update", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-efs-provisioner
subjects:
  - kind: ServiceAccount
    name: efs-provisioner
     # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: ClusterRole
  name: efs-provisioner-runner
  apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-efs-provisioner
rules:
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "list", "watch", "create", "update", "patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-efs-provisioner
subjects:
  - kind: ServiceAccount
    name: efs-provisioner
    # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: Role
  name: leader-locking-efs-provisioner
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: efs-provisioner
data:
  file.system.id: fs-c22a24bb
  aws.region: us-east-2
  provisioner.name: synadia.com/aws-efs
  dns.name: ""
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name: efs-provisioner
spec:
  replicas: 1
  strategy:
    type: Recreate 
  template:
    metadata:
      labels:
        app: efs-provisioner
    spec:
      serviceAccountName: efs-provisioner
      containers:
        - name: efs-provisioner
          image: quay.io/external_storage/efs-provisioner:latest
          env:
            - name: FILE_SYSTEM_ID
              valueFrom:
                configMapKeyRef:
                  name: efs-provisioner
                  key: file.system.id
            - name: AWS_REGION
              valueFrom:
                configMapKeyRef:
                  name: efs-provisioner
                  key: aws.region
            - name: DNS_NAME
              valueFrom:
                configMapKeyRef:
                  name: efs-provisioner
                  key: dns.name
​
            - name: PROVISIONER_NAME
              valueFrom:
                configMapKeyRef:
                  name: efs-provisioner
                  key: provisioner.name
          volumeMounts:
            - name: pv-volume
              mountPath: /efs
      volumes:
        - name: pv-volume
          nfs:
            server: fs-c22a24bb.efs.us-east-2.amazonaws.com
            path: /
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: aws-efs
provisioner: synadia.com/aws-efs
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: efs
  annotations:
    volume.beta.kubernetes.io/storage-class: "aws-efs"
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Mi
Result of deploying the manifest:
serviceaccount/efs-provisioner                                        created 
clusterrole.rbac.authorization.k8s.io/efs-provisioner-runner          created 
clusterrolebinding.rbac.authorization.k8s.io/run-efs-provisioner      created 
role.rbac.authorization.k8s.io/leader-locking-efs-provisioner         created 
rolebinding.rbac.authorization.k8s.io/leader-locking-efs-provisioner  created 
configmap/efs-provisioner                                             created 
deployment.extensions/efs-provisioner                                 created 
storageclass.storage.k8s.io/aws-efs                                   created 
persistentvolumeclaim/efs                                             created
Setting up the NATS Streaming cluster
Now create a NATS Streaming cluster with FT mode enabled and using NATS embedded mode that is mounting the EFS volume:
---
apiVersion: v1
kind: Service
metadata:
  name: stan
  labels:
    app: stan
spec:
  selector:
    app: stan
  clusterIP: None
  ports:
  - name: client
    port: 4222
  - name: cluster
    port: 6222
  - name: monitor
    port: 8222
  - name: metrics
    port: 7777
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: stan-config
data:
  stan.conf: |
    http: 8222
​
    cluster {
      port: 6222
      routes [
        nats://stan:6222
      ]
      cluster_advertise: $CLUSTER_ADVERTISE
      connect_retries: 10
    }
    streaming {
      id: test-cluster
      store: file
      dir: /data/stan/store
      ft_group_name: "test-cluster"
      file_options {
          buffer_size: 32mb
          sync_on_flush: false
          slice_max_bytes: 512mb
          parallel_recovery: 64
      }
      store_limits {
          max_channels: 10
          max_msgs: 0
          max_bytes: 256gb
          max_age: 1h
          max_subs: 128
      }  
    }
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: stan
  labels:
    app: stan
spec:
  selector:
    matchLabels:
      app: stan
  serviceName: stan
  replicas: 3
  volumeClaimTemplates:
  - metadata:
      name: efs
      annotations:
        volume.beta.kubernetes.io/storage-class: "aws-efs"
    spec:
      accessModes: [ "ReadWriteMany" ]
      resources:
        requests:
          storage: 1Mi
  template:
    metadata:
      labels:
        app: stan
    spec:
      # STAN Server
      terminationGracePeriodSeconds: 30
​
      containers:
      - name: stan
        image: nats-streaming:latest
​
        ports:
        # In case of NATS embedded mode expose these ports
        - containerPort: 4222
          name: client
        - containerPort: 6222
          name: cluster
        - containerPort: 8222
          name: monitor
        args:
         - "-sc"
         - "/etc/stan-config/stan.conf"
​
        # Required to be able to define an environment variable
        # that refers to other environment variables.  This env var
        # is later used as part of the configuration file.
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: CLUSTER_ADVERTISE
          value: $(POD_NAME).stan.$(POD_NAMESPACE).svc
        volumeMounts:
          - name: config-volume
            mountPath: /etc/stan-config
          - name: efs
            mountPath: /data/stan
        resources:
          requests:
            cpu: 0
        livenessProbe:
          httpGet:
            path: /
            port: 8222
          initialDelaySeconds: 10
          timeoutSeconds: 5
      - name: metrics
        image: synadia/prometheus-nats-exporter:0.5.0
        args:
        - -connz
        - -routez
        - -subz
        - -varz
        - -channelz
        - -serverz
        - http://localhost:8222
        ports:
        - containerPort: 7777
          name: metrics
      volumes:
      - name: config-volume
        configMap:
          name: stan-config
Your cluster now will look something like this:
kubectl get pods
NAME                                     READY   STATUS    RESTARTS   AGE
efs-provisioner-6b7866dd4-4k5wx          1/1     Running   0          21m
stan-0                                   2/2     Running   0          6m35s
stan-1                                   2/2     Running   0          4m56s
stan-2                                   2/2     Running   0          4m42s
If everything was setup properly, one of the servers will be the active node.
$ kubectl logs stan-0 -c stan
[1] 2019/12/04 20:40:40.429359 [INF] STREAM: Starting nats-streaming-server[test-cluster] version 0.16.2
[1] 2019/12/04 20:40:40.429385 [INF] STREAM: ServerID: 7j3t3Ii7e2tifWqanYKwFX
[1] 2019/12/04 20:40:40.429389 [INF] STREAM: Go version: go1.11.13
[1] 2019/12/04 20:40:40.429392 [INF] STREAM: Git commit: [910d6e1]
[1] 2019/12/04 20:40:40.454212 [INF] Starting nats-server version 2.0.4
[1] 2019/12/04 20:40:40.454360 [INF] Git commit [c8ca58e]
[1] 2019/12/04 20:40:40.454522 [INF] Starting http monitor on 0.0.0.0:8222
[1] 2019/12/04 20:40:40.454830 [INF] Listening for client connections on 0.0.0.0:4222
[1] 2019/12/04 20:40:40.454841 [INF] Server id is NB3A5RSGABLJP3WUYG6VYA36ZGE7MP5GVQIQVRG6WUYSRJA7B2NNMW57
[1] 2019/12/04 20:40:40.454844 [INF] Server is ready
[1] 2019/12/04 20:40:40.456360 [INF] Listening for route connections on 0.0.0.0:6222
[1] 2019/12/04 20:40:40.481927 [INF] STREAM: Starting in standby mode
[1] 2019/12/04 20:40:40.488193 [ERR] Error trying to connect to route (attempt 1): dial tcp: lookup stan on 10.100.0.10:53: no such host
[1] 2019/12/04 20:40:41.489688 [INF] 192.168.52.76:40992 - rid:6 - Route connection created
[1] 2019/12/04 20:40:41.489788 [INF] 192.168.52.76:40992 - rid:6 - Router connection closed
[1] 2019/12/04 20:40:41.489695 [INF] 192.168.52.76:6222 - rid:5 - Route connection created
[1] 2019/12/04 20:40:41.489955 [INF] 192.168.52.76:6222 - rid:5 - Router connection closed
[1] 2019/12/04 20:40:41.634944 [INF] STREAM: Server is active
[1] 2019/12/04 20:40:41.634976 [INF] STREAM: Recovering the state...
[1] 2019/12/04 20:40:41.655526 [INF] STREAM: No recovered state
[1] 2019/12/04 20:40:41.671435 [INF] STREAM: Message store is FILE
[1] 2019/12/04 20:40:41.671448 [INF] STREAM: Store location: /data/stan/store
[1] 2019/12/04 20:40:41.671524 [INF] STREAM: ---------- Store Limits ----------
[1] 2019/12/04 20:40:41.671527 [INF] STREAM: Channels:                   10
[1] 2019/12/04 20:40:41.671529 [INF] STREAM: --------- Channels Limits --------
[1] 2019/12/04 20:40:41.671531 [INF] STREAM:   Subscriptions:           128
[1] 2019/12/04 20:40:41.671533 [INF] STREAM:   Messages     :     unlimited
[1] 2019/12/04 20:40:41.671535 [INF] STREAM:   Bytes        :     256.00 GB
[1] 2019/12/04 20:40:41.671537 [INF] STREAM:   Age          :        1h0m0s
[1] 2019/12/04 20:40:41.671539 [INF] STREAM:   Inactivity   :     unlimited *
[1] 2019/12/04 20:40:41.671541 [INF] STREAM: ----------------------------------
[1] 2019/12/04 20:40:41.671546 [INF] STREAM: Streaming Server is ready
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