Setup TDengine Cluster on Kubernetes
Create a config map for TDengine: taoscfg.yaml.
---
apiVersion: v1
kind: ConfigMap
metadata:
name: taoscfg
labels:
app: tdengine
data:
CLUSTER: "1"
TAOS_KEEP: "3650"
TAOS_DEBUG_FLAG: "135"
Service config taosd-service.yaml for each port we will use, here note that the metadata.name (setted as "taosd") will be used in next step:
---
apiVersion: v1
kind: Service
metadata:
name: "taosd"
labels:
app: "tdengine"
spec:
ports:
- name: tcp6030
protocol: "TCP"
port: 6030
- name: tcp6035
protocol: "TCP"
port: 6035
- name: tcp6041
protocol: "TCP"
port: 6041
- name: udp6030
protocol: "UDP"
port: 6030
- name: udp6031
protocol: "UDP"
port: 6031
- name: udp6032
protocol: "UDP"
port: 6032
- name: udp6033
protocol: "UDP"
port: 6033
- name: udp6034
protocol: "UDP"
port: 6034
- name: udp6035
protocol: "UDP"
port: 6035
- name: udp6036
protocol: "UDP"
port: 6036
- name: udp6037
protocol: "UDP"
port: 6037
- name: udp6038
protocol: "UDP"
port: 6038
- name: udp6039
protocol: "UDP"
port: 6039
- name: udp6040
protocol: "UDP"
port: 6040
selector:
app: "tdengine"
We use StatefulSet config tdengine.yaml for TDengine.
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: "tdengine"
labels:
app: "tdengine"
spec:
serviceName: "taosd"
replicas: 2
updateStrategy:
type: RollingUpdate
selector:
matchLabels:
app: "tdengine"
template:
metadata:
name: "tdengine"
labels:
app: "tdengine"
spec:
containers:
- name: "tdengine"
image: "tdengine/tdengine:latest"
imagePullPolicy: "Always"
envFrom:
- configMapRef:
name: taoscfg
ports:
- name: tcp6030
protocol: "TCP"
containerPort: 6030
- name: tcp6035
protocol: "TCP"
containerPort: 6035
- name: tcp6041
protocol: "TCP"
containerPort: 6041
- name: udp6030
protocol: "UDP"
containerPort: 6030
- name: udp6031
protocol: "UDP"
containerPort: 6031
- name: udp6032
protocol: "UDP"
containerPort: 6032
- name: udp6033
protocol: "UDP"
containerPort: 6033
- name: udp6034
protocol: "UDP"
containerPort: 6034
- name: udp6035
protocol: "UDP"
containerPort: 6035
- name: udp6036
protocol: "UDP"
containerPort: 6036
- name: udp6037
protocol: "UDP"
containerPort: 6037
- name: udp6038
protocol: "UDP"
containerPort: 6038
- name: udp6039
protocol: "UDP"
containerPort: 6039
- name: udp6040
protocol: "UDP"
containerPort: 6040
env:
# POD_NAME for FQDN config
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
# SERVICE_NAME and NAMESPACE for fqdn resolve
- name: SERVICE_NAME
value: "taosd"
- name: STS_NAME
value: "tdengine"
- name: STS_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
# TZ for timezone settings, we recommend to always set it.
- name: TZ
value: "Asia/Shanghai"
# TAOS_ prefix will configured in taos.cfg, strip prefix and camelCase.
- name: TAOS_SERVER_PORT
value: "6030"
# Must set if you want a cluster.
- name: TAOS_FIRST_EP
value: "$(STS_NAME)-0.$(SERVICE_NAME).$(STS_NAMESPACE).svc.cluster.local:$(TAOS_SERVER_PORT)"
# TAOS_FQND should always be setted in k8s env.
- name: TAOS_FQDN
value: "$(POD_NAME).$(SERVICE_NAME).$(STS_NAMESPACE).svc.cluster.local"
volumeMounts:
- name: taosdata
mountPath: /var/lib/taos
readinessProbe:
exec:
command:
- taos
- -s
- "show mnodes"
initialDelaySeconds: 5
timeoutSeconds: 5000
livenessProbe:
tcpSocket:
port: 6030
initialDelaySeconds: 15
periodSeconds: 20
volumeClaimTemplates:
- metadata:
name: taosdata
spec:
accessModes:
- "ReadWriteOnce"
storageClassName: "standard"
resources:
requests:
storage: "10Gi"
Add them to kubernetes.
kubectl apply -f taoscfg.yaml
kubectl apply -f taosd-service.yaml
kubectl apply -f tdengine.yaml
The script will create a two node TDengine cluster on k8s.
Execute show dnodes in taos shell:
kubectl exec -i -t tdengine-0 -- taos -s "show dnodes"
kubectl exec -i -t tdengine-1 -- taos -s "show dnodes"
Well, the current dnodes list shows:
Welcome to the TDengine shell from Linux, Client Version:2.1.1.0
Copyright (c) 2020 by TAOS Data, Inc. All rights reserved.
taos> show dnodes
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 1 | 40 | ready | any | 2021-06-01 17:13:24.181 | |
2 | tdengine-1.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 17:14:09.257 | |
Query OK, 2 row(s) in set (0.000997s)
Scale Up
TDengine on Kubernetes could automatically scale up with:
kubectl scale statefulsets tdengine --replicas=4
Check if scale-up works:
kubectl get pods -l app=tdengine
Results:
NAME READY STATUS RESTARTS AGE
tdengine-0 1/1 Running 0 161m
tdengine-1 1/1 Running 0 161m
tdengine-2 1/1 Running 0 32m
tdengine-3 1/1 Running 0 32m
Check TDengine dnodes:
kubectl exec -i -t tdengine-0 -- taos -s "show dnodes"
Results:
Welcome to the TDengine shell from Linux, Client Version:2.1.1.0
Copyright (c) 2020 by TAOS Data, Inc. All rights reserved.
taos> show dnodes
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 11:58:12.915 | |
2 | tdengine-1.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 11:58:33.127 | |
3 | tdengine-2.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 14:07:27.078 | |
4 | tdengine-3.taosd.default.sv... | 1 | 40 | ready | any | 2021-06-01 14:07:48.362 | |
Query OK, 4 row(s) in set (0.001293s)
Scale Down
Let's try scale down from 3 to 2.
First, we scale up the TDengine cluster to 3 nodes:
kubectl scale statefulsets tdengine --replicas=3
show dnodes in taos shell:
taos> show dnodes
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 1 | 40 | ready | any | 2021-06-01 16:27:24.852 | |
2 | tdengine-1.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 16:27:53.339 | |
3 | tdengine-2.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 16:28:49.787 | |
Query OK, 3 row(s) in set (0.001101s)
To perform a right scale-down, we should drop the last dnode in taos shell first:
kubectl exec -i -t tdengine-0 -- taos -s "drop dnode 'tdengine-2.taosd.default.svc.cluster.local:6030'"
Then scale down to 2.
kubectl scale statefulsets tdengine --replicas=2
Extra relicas pods will be teminated, and retain 2 pods.
Type kubectl get pods -l app=tdengine to check pods.
NAME READY STATUS RESTARTS AGE
tdengine-0 1/1 Running 0 3h40m
tdengine-1 1/1 Running 0 3h40m
Also need to remove the pvc(if no, scale-up will be failed next):
kubectl delete pvc taosdata-tdengine-2
Now your TDengine cluster is safe.
Scale up again will be ok:
kubectl scale statefulsets tdengine --replicas=3
show dnodes results:
taos> show dnodes
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 1 | 40 | ready | any | 2021-06-01 16:27:24.852 | |
2 | tdengine-1.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 16:27:53.339 | |
4 | tdengine-2.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 16:40:49.177 | |
Let's do something BAD Case 1
Scale it up to 4 and then scale down to 2 directly. Deleted pods are offline now:
Welcome to the TDengine shell from Linux, Client Version:2.1.1.0
Copyright (c) 2020 by TAOS Data, Inc. All rights reserved.
taos> show dnodes
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 11:58:12.915 | |
2 | tdengine-1.taosd.default.sv... | 0 | 40 | ready | any | 2021-06-01 11:58:33.127 | |
3 | tdengine-2.taosd.default.sv... | 0 | 40 | offline | any | 2021-06-01 14:07:27.078 | status msg timeout |
4 | tdengine-3.taosd.default.sv... | 1 | 40 | offline | any | 2021-06-01 14:07:48.362 | status msg timeout |
Query OK, 4 row(s) in set (0.001236s)
But we can't drop the offline dnodes, the dnode will stuck in dropping mode (if you call drop dnode 'fqdn:6030').
Let's do something BAD Case 2
Note that if the remaining dnodes is less than the database replica, it will cause error untill you scale it up again.
Create database with replica 2, and insert data to an table:
kubectl exec -i -t tdengine-0 -- \
taos -s \
"create database if not exists test replica 2;
use test;
create table if not exists t1(ts timestamp, n int);
insert into t1 values(now, 1)(now+1s, 2);"
Scale down to replica 1 (bad behavior):
kubectl scale statefulsets tdengine --replicas=1
Now in taos shell, all operations with database test are not valid even if you call drop dnode after scale down.
taos> show dnodes;
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 2 | 40 | ready | any | 2021-06-01 15:55:52.562 | |
2 | tdengine-1.taosd.default.sv... | 1 | 40 | offline | any | 2021-06-01 15:56:07.212 | status msg timeout |
Query OK, 2 row(s) in set (0.000845s)
taos> show dnodes;
id | end_point | vnodes | cores | status | role | create_time | offline reason |
======================================================================================================================================
1 | tdengine-0.taosd.default.sv... | 2 | 40 | ready | any | 2021-06-01 15:55:52.562 | |
2 | tdengine-1.taosd.default.sv... | 1 | 40 | offline | any | 2021-06-01 15:56:07.212 | status msg timeout |
Query OK, 2 row(s) in set (0.000837s)
taos> use test;
Database changed.
taos> insert into t1 values(now, 3);
DB error: Unable to resolve FQDN (0.013874s)
So, before scale-down, please check the max value of replica among all databases, and be sure to do drop dnode step.
Clean Up TDengine StatefulSet
To complete remove tdengine statefulset, type:
kubectl delete statefulset -l app=tdengine
kubectl delete svc -l app=tdengine
kubectl delete pvc -l app=tdengine
kubectl delete configmap taoscfg