Altinity / Altinity/clickhouse-operator
Question: change keeper replica count (decrease 5 -> 3)
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Description
So I have a Clickhouse cluster of 3 shards and 2 replicas. When I created the keeper I added 5 keepers (not sure why).
My question is, is it safe to just decrease that value to 3 keepers and update the config spec.configuration.zookeeper.nodes to point to the 3 keepers?
ClickHouseKeeperInstallation:
apiVersion: "clickhouse-keeper.altinity.com/v1"
kind: "ClickHouseKeeperInstallation"
metadata:
name: keeper
spec:
configuration:
clusters:
- name: "cluster-name"
layout:
replicasCount: 5
settings:
logger/level: "trace"
logger/console: "true"
listen_host: "0.0.0.0"
keeper_server/four_letter_word_white_list: "*"
keeper_server/coordination_settings/raft_logs_level: "information"
prometheus/endpoint: "/metrics"
prometheus/port: "7000"
prometheus/metrics: "true"
prometheus/events: "true"
prometheus/asynchronous_metrics: "true"
prometheus/status_info: "false"
defaults:
templates:
podTemplate: default
dataVolumeClaimTemplate: default
templates:
podTemplates:
- name: default
metadata:
labels:
app: clickhouse-keeper
spec:
nodeSelector:
node.kubernetes.io/instance-type: ccx13
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app"
operator: In
values:
- clickhouse-keeper
topologyKey: "kubernetes.io/hostname"
containers:
- name: clickhouse-keeper
imagePullPolicy: IfNotPresent
image: clickhouse/clickhouse-keeper:24.12
resources:
requests:
memory: "500Mi"
cpu: "0.2"
limits:
memory: "1Gi"
cpu: "1"
securityContext:
fsGroup: 101
volumeClaimTemplates:
- name: default
reclaimPolicy: Retain
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 5Gi
ClickhouseInstallation (relevant part):
apiVersion: "clickhouse.altinity.com/v1"
kind: "ClickHouseInstallation"
metadata:
name: "chi-cluster"
spec:
defaults:
templates:
dataVolumeClaimTemplate: default
podTemplate: clickhouse-pod-template
serviceTemplate: svc-template
configuration:
zookeeper:
nodes:
- host: chk-keeper-openpanel-0-0
port: 2181
- host: chk-keeper-openpanel-0-1
port: 2181
- host: chk-keeper-openpanel-0-2
port: 2181
- host: chk-keeper-openpanel-0-3
port: 2181
- host: chk-keeper-openpanel-0-4
port: 2181
clusters:
- name: "cluster-name"
secure: "yes"
layout:
shardsCount: 3
replicasCount: 2
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the ClickHouseKeeperInstallation configuration at clusters.layout.replicasCount and the ClickHouseInstallation configuration at zookeeper.nodes. Determine the documented procedure and safety requirements for reducing the keeper count, then update the relevant operator documentation if an appropriate location is identified.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- kubernetes
- Domain
- databases, infrastructure
- Issue type
- Documentation
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Active
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100