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Using Prometheus (CoreOS operator) with KubeDB
This tutorial will show you how to monitor KubeDB databases using Prometheus via CoreOS Prometheus Operator.
Before You Begin
At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.
Note that the yaml files that are used in this tutorial, stored in docs/examples folder in GitHub repository kubedb/cli.
Deploy CoreOS-Prometheus Operator
In RBAC enabled cluster
If RBAC is enabled, Run the following command to prepare your cluster for this tutorial:
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/rbac/demo-0.yaml
namespace "demo" created
clusterrole "prometheus-operator" created
serviceaccount "prometheus-operator" created
clusterrolebinding "prometheus-operator" created
deployment "prometheus-operator" created
$ kubectl get pods -n demo --watch
NAME READY STATUS RESTARTS AGE
prometheus-operator-79cb9dcd4b-2njgq 1/1 Running 0 2m
$ kubectl get crd
NAME AGE
alertmanagers.monitoring.coreos.com 11m
prometheuses.monitoring.coreos.com 11m
servicemonitors.monitoring.coreos.com 11m
Once the Prometheus operator CRDs are registered, run the following command to create a Prometheus.
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/rbac/demo-1.yaml
clusterrole "prometheus" created
serviceaccount "prometheus" created
clusterrolebinding "prometheus" created
prometheus "prometheus" created
service "prometheus" created
# Verify RBAC stuffs
$ kubectl get clusterroles
NAME AGE
prometheus 48s
prometheus-operator 1m
$ kubectl get clusterrolebindings
NAME AGE
prometheus 7s
prometheus-operator 25s
$ kubectl get serviceaccounts -n demo
NAME SECRETS AGE
default 1 5m
prometheus 1 4m
prometheus-operator 1 5m
In RBAC *not* enabled cluster
If RBAC is not enabled, Run the following command to prepare your cluster for this tutorial:
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/demo-0.yaml
namespace "demo" created
deployment "prometheus-operator" created
$ kubectl get pods -n demo --watch
NAME READY STATUS RESTARTS AGE
prometheus-operator-5dcd844486-nprmk 0/1 ContainerCreating 0 27s
prometheus-operator-5dcd844486-nprmk 1/1 Running 0 46s
$ kubectl get crd
NAME AGE
alertmanagers.monitoring.coreos.com 45s
prometheuses.monitoring.coreos.com 44s
servicemonitors.monitoring.coreos.com 44s
Once the Prometheus operator CRDs are registered, run the following command to create a Prometheus.
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/demo-1.yaml
prometheus "prometheus" created
service "prometheus" created
Prometheus Dashboard
Now to open prometheus dashboard on Browser:
$ kubectl get svc -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
prometheus LoadBalancer 10.110.173.135 <pending> 9090:30900/TCP 11s
prometheus-operated ClusterIP None <none> 9090/TCP 11s
$ minikube ip
192.168.99.100
$ minikube service prometheus -n demo --url
http://192.168.99.100:30900
Now, open your browser and go to the following URL: http://{minikube-ip}:{prometheus-svc-nodeport} to visit Prometheus Dashboard. According to the above example, this URL will be http://192.168.99.100:30900.
Create a Redis database
KubeDB implements a Redis CRD to define the specification of a Redis database. Below is the Redis object created in this tutorial.
apiVersion: kubedb.com/v1alpha1
kind: Redis
metadata:
name: redis-mon-coreos
namespace: demo
spec:
version: 4
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Mi
monitor:
agent: prometheus.io/coreos-operator
prometheus:
namespace: demo
labels:
app: kubedb
interval: 10s
The Redis CRD object contains monitor field in it’s spec. It is also possible to add CoreOS-Prometheus monitor to an existing Redis database by adding the below part in it’s spec field.
spec:
monitor:
agent: prometheus.io/coreos-operator
prometheus:
namespace: demo
labels:
app: kubedb
interval: 10s
| Keys | Value | Description |
|---|---|---|
spec.monitor.agent | string | Required. Indicates the monitoring agent used. Only valid value currently is coreos-prometheus-operator |
spec.monitor.prometheus.namespace | string | Required. Indicates namespace where service monitors are created. This must be the same namespace of the Prometheus instance. |
spec.monitor.prometheus.labels | map | Required. Indicates labels applied to service monitor. |
spec.monitor.prometheus.interval | string | Optional. Indicates the scrape interval for database exporter endpoint (eg, ’10s') |
spec.monitor.prometheus.port | int | Optional. Indicates the port for database exporter endpoint (default is 56790) |
Known Limitations: If the database password is updated, exporter must be restarted to use the new credentials. This issue is tracked here.
Run the following command to deploy the above Redis CRD object.
$ kubedb create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/redis/monitoring/coreos-operator/demo-1.yaml
validating "https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/redis/monitoring/coreos-operator/demo-1.yaml"
redis "redis-mon-coreos" created
Here,
spec.versionis the version of Redis database. In this tutorial, a Redis 4 database is going to be created.spec.storagespecifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. You can specify any StorageClass available in your cluster with appropriate resource requests. If no storage spec is given, anemptyDiris used.spec.monitorspecifies that CoreOS Prometheus operator is used to monitor this database instance. A ServiceMonitor should be created in thedemonamespace with labelapp=kubedb. The exporter endpoint should be scrapped every 10 seconds.
KubeDB operator watches for Redis objects using Kubernetes api. When a Redis object is created, KubeDB operator will create a new StatefulSet and a ClusterIP Service with the matching crd name. KubeDB operator will also create a governing service for StatefulSets with the name kubedb, if one is not already present.
$ kubedb get rd -n demo
NAME STATUS AGE
redis-mon-coreos Creating 36s
$ kubedb get rd -n demo
NAME STATUS AGE
redis-mon-coreos Running 26s
$ kubedb describe rd -n demo redis-mon-coreos
Name: redis-mon-coreos
Namespace: demo
StartTimestamp: Mon, 12 Feb 2018 17:12:03 +0600
Status: Running
Volume:
StorageClass: standard
Capacity: 50Mi
Access Modes: RWO
StatefulSet:
Name: redis-mon-coreos
Replicas: 1 current / 1 desired
CreationTimestamp: Mon, 12 Feb 2018 17:12:05 +0600
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: redis-mon-coreos
Type: ClusterIP
IP: 10.108.164.193
Port: db 6379/TCP
Port: prom-http 56790/TCP
Monitoring System:
Agent: prometheus.io/coreos-operator
Prometheus:
Namespace: demo
Labels: app=kubedb
Interval: 10s
Events:
FirstSeen LastSeen Count From Type Reason Message
--------- -------- ----- ---- -------- ------ -------
46s 46s 1 Redis operator Normal Successful Successfully patched StatefulSet
46s 46s 1 Redis operator Normal Successful Successfully patched Redis
48s 48s 1 Redis operator Normal Successful Successfully created StatefulSet
48s 48s 1 Redis operator Normal Successful Successfully created Redis
1m 1m 1 Redis operator Normal Successful Successfully created Service
Since spec.monitoring was configured, a ServiceMonitor object is created accordingly. You can verify it running the following commands:
$ kubectl get servicemonitor -n demo
NAME AGE
kubedb-demo-redis-mon-coreos 1m
$ kubectl get servicemonitor -n demo kubedb-demo-redis-mon-coreos -o yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
clusterName: ""
creationTimestamp: 2018-02-12T11:12:20Z
labels:
app: kubedb
monitoring.appscode.com/service: redis-mon-coreos.demo
name: kubedb-demo-redis-mon-coreos
namespace: demo
resourceVersion: "47974"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/demo/servicemonitors/kubedb-demo-redis-mon-coreos
uid: 9824ef63-0fe5-11e8-a2d6-08002751ae8c
spec:
endpoints:
- interval: 10s
path: /kubedb.com/v1alpha1/namespaces/demo/redises/redis-mon-coreos/metrics
port: prom-http
targetPort: 0
namespaceSelector:
matchNames:
- demo
selector:
matchLabels:
kubedb.com/kind: Redis
kubedb.com/name: redis-mon-coreos
Now, if you go the Prometheus Dashboard, you should see that this database endpoint as one of the targets.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
$ kubedb delete rd,drmn -n demo --all --force
# In rbac enabled cluster,
# $ kubectl delete clusterrolebindings prometheus-operator prometheus
# $ kubectl delete clusterrole prometheus-operator prometheus
$ kubectl delete ns demo
namespace "demo" deleted
Next Steps
- Monitor your Redis database with KubeDB using out-of-the-box builtin-Prometheus.
- Detail concepts of Redis object.
- Use private Docker registry to deploy Redis with KubeDB.
- Wondering what features are coming next? Please visit here.
- Want to hack on KubeDB? Check our contribution guidelines.