NATS Streaming with Fault Tolerance.
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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 stan-k8s \
--nodes 3 \
--node-type=t3.large \ # t3.small
--region=us-east-2
# Get the credentials for your cluster
eksctl utils write-kubeconfig --name stan-k8s --region us-east-2For 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:
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:
---
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: apps/v1
metadata:
name: efs-provisioner
spec:
replicas: 1
selector:
matchLabels:
app: efs-provisioner
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: 1MiResult 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 createdNow 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-0.stan:6222
nats://stan-1.stan:6222
nats://stan-2.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:
template:
metadata:
labels:
app: stan
spec:
# STAN Server
terminationGracePeriodSeconds: 30
containers:
- name: stan
image: nats-streaming:alpine
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
- name: efs
persistentVolumeClaim:
claimName: efsYour 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 4m42sIf 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 readyFirst need to create a PVC (PersistentVolumeClaim), in Azure we can use azurefile to get a volume with ReadWriteMany:
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: stan-efs
annotations:
volume.beta.kubernetes.io/storage-class: "azurefile"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 100MiNext create a NATS cluster using the Helm charts:
helm repo add nats https://nats-io.github.io/k8s/helm/charts/
helm install nats nats/natsTo create an FT setup using AzureFile you can use the following Helm chart values file:
stan:
image: nats-streaming:alpine
replicas: 2
nats:
url: nats://nats:4222
store:
type: file
ft:
group: my-group
file:
path: /data/stan/store
volume:
enabled: true
# Mount path for the volume.
mount: /data/stan
# FT mode requires a single shared ReadWriteMany PVC volume.
persistentVolumeClaim:
claimName: stan-efsNow deploy with Helm:
helm install stan nats/stan -f ./examples/deploy-stan-ft-file.yamlSend a few commands to the NATS Server to which STAN/NATS Streaming is connected:
kubectl port-forward nats-0 4222:4222 &
stan-pub -c stan foo bar.1
stan-pub -c stan foo bar.2
stan-pub -c stan foo bar.3Subscribe to get all the messages:
stan-sub -c stan -all foo
