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High Availability
High availability is not only important for customer-facing software but if the monitoring infrastructure is not highly available, then there is a risk that operations people are not notified of alerts. Therefore high availability must be just as thought through for the monitoring stack, as for anything else.
VMAgent
To run VMAgent in a highly available manner you have to configure deduplication at Victoria Metrics first doc
Then increase replicas for VMAgent.
create VMSingle with dedup flag
cat <<EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMSingle
metadata:
name: example-vmsingle-persisted
spec:
retentionPeriod: "1"
extraArgs:
dedup.minScrapeInterval: 60s
EOF
create VMAgent with 2 replicas
cat <<EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
name: example-vmagent
spec:
serviceScrapeNamespaceSelector: {}
podScrapeNamespaceSelector: {}
podScrapeSelector: {}
serviceScrapeSelector: {}
scrapeInterval: 60s
vmAgentExternalLabelName: vmagent-ha
replicaCount: 2
remoteWrite:
- url: "http://vmsingle-example-vmsingle-persisted.default.svc:8429/api/v1/write"
EOF
Sharding
Sharding for VMAgent distributes scraping between multiple deployments of VMAgent.
more info https://victoriametrics.github.io/vmagent.html#scraping-big-number-of-targets
Example usage:
cat <<EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
name: example-vmagent
spec:
serviceScrapeNamespaceSelector: {}
podScrapeNamespaceSelector: {}
podScrapeSelector: {}
serviceScrapeSelector: {}
scrapeInterval: 60s
vmAgentExternalLabelName: vmagent-ha
shardCount: 5
replicaCount: 2
remoteWrite:
- url: "http://vmsingle-example-vmsingle-persisted.default.svc:8429/api/v1/write"
EOF
This configuration produces 5 deployments with 2 replicas at each. Each deployment has its own shard num and scrapes only 1/5 of all targets.
StatefulMode
In StatefulMode VMAgent doesn't lose state of the PersistentQueue (file-based buffer size for unsent data) on pod restarts.
Operator creates StatefulSet and, with provided PersistenVolumeClaimTemplate at StatefulStorage configuration param, metrics queue is stored on disk.
Example of configuration:
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
name: example-persistent
spec:
selectAllByDefault: true
vmAgentExternalLabelName: vmagent-ha
replicaCount: 2
remoteWrite:
- url: "http://vmsingle-example-vmsingle-persisted.default.svc:8429/api/v1/write"
statefulMode: true
statefulStorage:
volumeClaimTemplate:
spec:
resources:
requests:
storage: 20Gi
VMAlert
It can be launched with multiple replicas without an additional configuration, alertmanager is responsible for alert deduplication.
Note, if you want to use VMAlert with high-available VMAlertmanager, which has more than 1 replica. You have to specify all pod fqdns
at VMAlert.spec.notifiers.[url]. Or you can use service discovery for notifier, examples:
alertmanager:
apiVersion: v1
kind: Secret
metadata:
name: vmalertmanager-example-alertmanager
labels:
app: vm-operator
type: Opaque
stringData:
alertmanager.yaml: |
global:
resolve_timeout: 5m
route:
group_by: ['job']
group_wait: 30s
group_interval: 5m
repeat_interval: 12h
receiver: 'webhook'
receivers:
- name: 'webhook'
webhook_configs:
- url: 'http://alertmanagerwh:30500/'
---
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlertmanager
metadata:
name: example
namespace: default
labels:
usage: dedicated
spec:
replicaCount: 2
configSecret: vmalertmanager-example-alertmanager
configSelector: {}
configNamespaceSelector: {}
vmalert with fqdns:
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlert
metadata:
name: example-ha
namespace: default
spec:
datasource:
url: http://vmsingle-example.default.svc:8429
notifiers:
- url: http://vmalertmanager-example-0.vmalertmanager-example.default.svc:9093
- url: http://vmalertmanager-example-1.vmalertmanager-example.default.svc:9093
vmalert with service discovery:
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlert
metadata:
name: example-ha
namespace: default
spec:
datasource:
url: http://vmsingle-example.default.svc:8429
notifiers:
- selector:
namespaceSelector:
matchNames:
- default
labelSelector:
matchLabels:
usage: dedicated
VMSingle
It doesn't support high availability by default, for such purpose use VMCluster or duplicate the setup.
VMCluster
The cluster version provides a full set of high availability features - metrics replication, node failover, horizontal scaling.
For using the cluster version you have to create the corresponding CRD object:
cat << EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMCluster
metadata:
name: example-vmcluster-persistent
spec:
retentionPeriod: "4"
replicationFactor: 2
vmstorage:
replicaCount: 2
storageDataPath: "/vm-data"
podMetadata:
labels:
owner: infra
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app.kubernetes.io/name"
operator: In
values:
- "vmstorage"
topologyKey: "kubernetes.io/hostname"
storage:
volumeClaimTemplate:
spec:
resources:
requests:
storage: 10Gi
resources:
limits:
cpu: "2"
memory: 2048Mi
vmselect:
replicaCount: 2
cacheMountPath: "/select-cache"
podMetadata:
labels:
owner: infra
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app.kubernetes.io/name"
operator: In
values:
- "vmselect"
topologyKey: "kubernetes.io/hostname"
storage:
volumeClaimTemplate:
spec:
resources:
requests:
storage: 2Gi
resources:
limits:
cpu: "1"
memory: "500Mi"
vminsert:
replicaCount: 2
podMetadata:
labels:
owner: infra
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app.kubernetes.io/name"
operator: In
values:
- "vminsert"
topologyKey: "kubernetes.io/hostname"
resources:
limits:
cpu: "1"
memory: "500Mi"
EOF
Then wait for the cluster becomes ready
kubectl get vmclusters -w
NAME INSERT COUNT STORAGE COUNT SELECT COUNT AGE STATUS
example-vmcluster-persistent 2 2 2 2s expanding
example-vmcluster-persistent 2 2 2 30s operational
Get links for connection by executing the command:
kubectl get svc -l app.kubernetes.io/instance=example-vmcluster-persistent
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
vminsert-example-vmcluster-persistent ClusterIP 10.96.34.94 <none> 8480/TCP 69s
vmselect-example-vmcluster-persistent ClusterIP None <none> 8481/TCP 79s
vmstorage-example-vmcluster-persistent ClusterIP None <none> 8482/TCP,8400/TCP,8401/TCP 85s
Now you can connect vmagent to vminsert and vmalert to vmselect
NOTE do not forget to create rbac for vmagent
cat << EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
name: example-vmagent
spec:
serviceScrapeNamespaceSelector: {}
serviceScrapeSelector: {}
podScrapeNamespaceSelector: {}
podScrapeSelector: {}
# Add fields here
replicaCount: 1
remoteWrite:
- url: "http://vminsert-example-vmcluster-persistent.default.svc.cluster.local:8480/insert/0/prometheus/api/v1/write"
EOF
Config for vmalert
cat << EOF | kubectl apply -f -
apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlert
metadata:
name: example-vmalert
spec:
# Add fields here
replicas: 1
datasource:
url: "http://vmselect-example-vmcluster-persistent.default.svc.cluster.local:8481/select/0/prometheus"
notifier:
url: "http://alertmanager-operated.default.svc:9093"
evaluationInterval: "10s"
ruleSelector: {}
EOF
Alertmanager
The final step of the high availability scheme is Alertmanager, when an alert triggers, actually fire alerts against all instances of an Alertmanager cluster.
The Alertmanager, starting with the v0.5.0 release, ships with a high availability mode. It implements a gossip protocol to synchronize instances of an Alertmanager cluster regarding notifications that have been sent out, to prevent duplicate notifications. It is an AP (available and partition tolerant) system. Being an AP system means that notifications are guaranteed to be sent at least once.
The Victoria Metrics Operator ensures that Alertmanager clusters are properly configured to run highly available on Kubernetes.