I just created a kubernetes cluster with --replicas 1 as the dgraph argument parameters in my .yaml config file.
How do i update the dgraph instance to use 3 replicas ?
Do i just update the .yaml config file with --replicas 3, and run kubectl apply -f config.yaml ?
Dear future reader. Do not confuse Dgraph replication with pod replication in the context of k8s. They are different things.
Thatās hard to explain. Did you keep the previous amount of instances? (there were 6 Alphas).
If so, you need to decide whether to add more instances or use the same amount.
You will need to remove some nodes before you begin - and add them again with the new config, but for those with no experience, there may happen problems in the process. So I recommend that you export your dataset and then create a new cluster and reimport your dataset. It is the safest.
the safest
I first started with a single node (instance) using this config:
kind: Service
metadata:
name: dgraph-zero-public
labels:
app: dgraph-zero
spec:
type: LoadBalancer
ports:
- port: 5080
targetPort: 5080
name: zero-grpc
- port: 6080
targetPort: 6080
name: zero-http
selector:
app: dgraph-zero
---
apiVersion: v1
kind: Service
metadata:
name: dgraph-alpha-public
labels:
app: dgraph-alpha
spec:
type: LoadBalancer
ports:
- port: 8080
targetPort: 8080
name: alpha-http
- port: 9080
targetPort: 9080
name: alpha-grpc
selector:
app: dgraph-alpha
---
apiVersion: v1
kind: Service
metadata:
name: dgraph-ratel-public
labels:
app: dgraph-ratel
spec:
type: LoadBalancer
ports:
- port: 8000
targetPort: 8000
name: ratel-http
selector:
app: dgraph-ratel
---
# This is a headless service which is necessary for discovery for a dgraph-zero StatefulSet.
# https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#creating-a-statefulset
apiVersion: v1
kind: Service
metadata:
name: dgraph-zero
labels:
app: dgraph-zero
spec:
ports:
- port: 5080
targetPort: 5080
name: zero-grpc
clusterIP: None
selector:
app: dgraph-zero
---
# This is a headless service which is necessary for discovery for a dgraph-alpha StatefulSet.
# https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#creating-a-statefulset
apiVersion: v1
kind: Service
metadata:
name: dgraph-alpha
labels:
app: dgraph-alpha
spec:
ports:
- port: 7080
targetPort: 7080
name: alpha-grpc-int
clusterIP: None
selector:
app: dgraph-alpha
---
# This StatefulSet runs 1 Dgraph Zero.
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: dgraph-zero
spec:
serviceName: "dgraph-zero"
replicas: 1
selector:
matchLabels:
app: dgraph-zero
template:
metadata:
labels:
app: dgraph-zero
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: app
operator: In
values:
- dgraph-zero
topologyKey: kubernetes.io/hostname
containers:
- name: zero
image: dgraph/dgraph:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 5080
name: zero-grpc
- containerPort: 6080
name: zero-http
volumeMounts:
- name: datadir
mountPath: /dgraph
env:
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
command:
- bash
- "-c"
- |
set -ex
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
idx=$(($ordinal + 1))
if [[ $ordinal -eq 0 ]]; then
exec dgraph zero --my=$(hostname -f):5080 --idx $idx --replicas 1
else
exec dgraph zero --my=$(hostname -f):5080 --peer dgraph-zero-0.dgraph-zero.${POD_NAMESPACE}.svc.cluster.local:5080 --idx $idx --replicas 1
fi
terminationGracePeriodSeconds: 60
volumes:
- name: datadir
persistentVolumeClaim:
claimName: datadir
updateStrategy:
type: RollingUpdate
volumeClaimTemplates:
- metadata:
name: datadir
annotations:
volume.alpha.kubernetes.io/storage-class: anything
spec:
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: 10Gi
---
# This StatefulSet runs 1 replicas of Dgraph Alpha.
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: dgraph-alpha
spec:
serviceName: "dgraph-alpha"
replicas: 1
selector:
matchLabels:
app: dgraph-alpha
template:
metadata:
labels:
app: dgraph-alpha
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: app
operator: In
values:
- dgraph-alpha
topologyKey: kubernetes.io/hostname
containers:
- name: alpha
image: dgraph/dgraph:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 7080
name: alpha-grpc-int
- containerPort: 8080
name: alpha-http
- containerPort: 9080
name: alpha-grpc
volumeMounts:
- name: datadir
mountPath: /dgraph
env:
# This should be the same namespace as the dgraph-zero
# StatefulSet to resolve a Dgraph Zero's DNS name for
# Alpha's --zero flag.
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
command:
- bash
- "-c"
- |
set -ex
dgraph alpha --my=$(hostname -f):7080 --lru_mb 1340 --zero dgraph-zero-0.dgraph-zero.${POD_NAMESPACE}.svc.cluster.local:5080
terminationGracePeriodSeconds: 600
volumes:
- name: datadir
persistentVolumeClaim:
claimName: datadir
updateStrategy:
type: RollingUpdate
volumeClaimTemplates:
- metadata:
name: datadir
annotations:
volume.alpha.kubernetes.io/storage-class: anything
spec:
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: 20Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: dgraph-ratel
labels:
app: dgraph-ratel
spec:
selector:
matchLabels:
app: dgraph-ratel
template:
metadata:
labels:
app: dgraph-ratel
spec:
containers:
- name: ratel
image: dgraph/dgraph:latest
ports:
- containerPort: 8000
command:
- dgraph-ratel
then i provisioned 2 extra nodes. After the 2 nodes where ready, i updated the config.yaml like so:
apiVersion: v1
kind: Service
metadata:
name: dgraph-zero-public
labels:
app: dgraph-zero
spec:
type: LoadBalancer
ports:
- port: 5080
targetPort: 5080
name: zero-grpc
- port: 6080
targetPort: 6080
name: zero-http
selector:
app: dgraph-zero
---
apiVersion: v1
kind: Service
metadata:
name: dgraph-alpha-public
labels:
app: dgraph-alpha
spec:
type: LoadBalancer
ports:
- port: 8080
targetPort: 8080
name: alpha-http
- port: 9080
targetPort: 9080
name: alpha-grpc
selector:
app: dgraph-alpha
---
apiVersion: v1
kind: Service
metadata:
name: dgraph-ratel-public
labels:
app: dgraph-ratel
spec:
type: LoadBalancer
ports:
- port: 8000
targetPort: 8000
name: ratel-http
selector:
app: dgraph-ratel
---
# This is a headless service which is necessary for discovery for a dgraph-zero StatefulSet.
# https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#creating-a-statefulset
apiVersion: v1
kind: Service
metadata:
name: dgraph-zero
labels:
app: dgraph-zero
spec:
ports:
- port: 5080
targetPort: 5080
name: zero-grpc
clusterIP: None
selector:
app: dgraph-zero
---
# This is a headless service which is necessary for discovery for a dgraph-alpha StatefulSet.
# https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#creating-a-statefulset
apiVersion: v1
kind: Service
metadata:
name: dgraph-alpha
labels:
app: dgraph-alpha
spec:
ports:
- port: 7080
targetPort: 7080
name: alpha-grpc-int
clusterIP: None
selector:
app: dgraph-alpha
---
# This StatefulSet runs 3 Dgraph Zero.
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: dgraph-zero
spec:
serviceName: "dgraph-zero"
replicas: 3
selector:
matchLabels:
app: dgraph-zero
template:
metadata:
labels:
app: dgraph-zero
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: app
operator: In
values:
- dgraph-zero
topologyKey: kubernetes.io/hostname
containers:
- name: zero
image: dgraph/dgraph:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 5080
name: zero-grpc
- containerPort: 6080
name: zero-http
volumeMounts:
- name: datadir
mountPath: /dgraph
env:
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
command:
- bash
- "-c"
- |
set -ex
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
idx=$(($ordinal + 1))
if [[ $ordinal -eq 0 ]]; then
exec dgraph zero --my=$(hostname -f):5080 --idx $idx --replicas 3
else
exec dgraph zero --my=$(hostname -f):5080 --peer dgraph-zero-0.dgraph-zero.${POD_NAMESPACE}.svc.cluster.local:5080 --idx $idx --replicas 3
fi
terminationGracePeriodSeconds: 60
volumes:
- name: datadir
persistentVolumeClaim:
claimName: datadir
updateStrategy:
type: RollingUpdate
volumeClaimTemplates:
- metadata:
name: datadir
annotations:
volume.alpha.kubernetes.io/storage-class: anything
spec:
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: 10Gi
---
# This StatefulSet runs 3 replicas of Dgraph Alpha.
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: dgraph-alpha
spec:
serviceName: "dgraph-alpha"
replicas: 3
selector:
matchLabels:
app: dgraph-alpha
template:
metadata:
labels:
app: dgraph-alpha
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: app
operator: In
values:
- dgraph-alpha
topologyKey: kubernetes.io/hostname
containers:
- name: alpha
image: dgraph/dgraph:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 7080
name: alpha-grpc-int
- containerPort: 8080
name: alpha-http
- containerPort: 9080
name: alpha-grpc
volumeMounts:
- name: datadir
mountPath: /dgraph
env:
# This should be the same namespace as the dgraph-zero
# StatefulSet to resolve a Dgraph Zero's DNS name for
# Alpha's --zero flag.
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
command:
- bash
- "-c"
- |
set -ex
dgraph alpha --my=$(hostname -f):7080 --lru_mb 1340 --zero dgraph-zero-0.dgraph-zero.${POD_NAMESPACE}.svc.cluster.local:5080
terminationGracePeriodSeconds: 600
volumes:
- name: datadir
persistentVolumeClaim:
claimName: datadir
updateStrategy:
type: RollingUpdate
volumeClaimTemplates:
- metadata:
name: datadir
annotations:
volume.alpha.kubernetes.io/storage-class: anything
spec:
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: 20Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: dgraph-ratel
labels:
app: dgraph-ratel
spec:
selector:
matchLabels:
app: dgraph-ratel
template:
metadata:
labels:
app: dgraph-ratel
spec:
containers:
- name: ratel
image: dgraph/dgraph:latest
ports:
- containerPort: 8000
command:
- dgraph-ratel
When i check all three nodes using:
`kubectl get pods -o wide --all-namespaces
all pods show a ārunningā status. and they seem to be distributed across the three nodes (instances)
Why do i need to remove some nodes ?
My bad, you donāt need. For a second I thought you was talking about making changes in general to the cluster. When you said āhow do i updateā I thought it was a general question. Despite the title. So, to just increase you donāt need to do anything.
I have a question there. I want to change the amount of the alpha from 3 to 6.There are some problem at random.
1ćall pods show a ārunningā status. But there is a zero that can not join the cluster.
2ćsome alpha show a " crashbackoff" status.
I have tried to use some method to solve it ,but failed. I confused whether i can change the amount of alpha at random.
Hey @Weilliam ,
When you have a question, please open a new topic. And reference other topics instead of commenting on them. For when you write in an old topic. It can trigger emails to the people involved. And not everyone likes to receive emails from old subjects.
Well, I never tried randomly run Dgraph configs - Dgraph configurations should be well planned a priori. This for sure can be challenging. If you open a new topic with steps about what you already accomplished. I can follow and try to work out something. But Iām not sure if we can be this hard (random).
We can try to reproduce this locally using scripts first.
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