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Manage KubeDB objects using CLIs
KubeDB CLI
KubeDB comes with its own cli. It is called kubedb cli. kubedb can be used to manage any KubeDB object. kubedb cli also performs various validations to improve ux. To install KubeDB cli on your workstation, follow the steps here.
How to Create objects
kubectl create creates a database CRD object in default namespace by default. Following command will create a Memcached object as specified in memcached.yaml.
$ kubectl create -f memcached-demo.yaml
memcached.kubedb.com/memcached-demo created
You can provide namespace as a flag --namespace. Provided namespace should match with namespace specified in input file.
$ kubectl create -f memcached-demo.yaml --namespace=kube-system
memcached.kubedb.com/memcached-demo created
kubectl create command also considers stdin as input.
cat memcached-demo.yaml | kubectl create -f -
How to List Objects
kubectl get command allows users to list or find any KubeDB object. To list all Memcached objects in default namespace, run the following command:
$ kubectl get memcached
NAME VERSION STATUS AGE
memcached-demo 1.6.22 Running 40s
memcached-dev 1.6.22 Running 40s
memcached-prod 1.6.22 Running 40s
memcached-qa 1.6.22 Running 40s
To get YAML of an object, use --output=yaml flag.
$ kubectl get memcached memcached-demo --output=yaml
apiVersion: kubedb.com/v1alpha2
kind: Memcached
metadata:
creationTimestamp: 2018-10-04T05:58:57Z
finalizers:
- kubedb.com
generation: 1
labels:
kubedb: cli-demo
name: memcached-demo
namespace: demo
resourceVersion: "6883"
selfLink: /apis/kubedb.com/v1alpha2/namespaces/default/memcacheds/memcached-demo
uid: 953df4d1-c79a-11e8-bb11-0800272ad446
spec:
podTemplate:
controller: {}
metadata: {}
spec:
resources:
limits:
cpu: 500m
memory: 128Mi
requests:
cpu: 250m
memory: 64Mi
replicas: 3
terminationPolicy: Halt
version: 1.6.22
status:
observedGeneration: 1$7916315637361465932
phase: Running
To get JSON of an object, use --output=json flag.
kubectl get memcached memcached-demo --output=json
To list all KubeDB objects, use following command:
$ kubectl get all -o wide
NAME VERSION STATUS AGE
mc/memcached-demo 1.6.22 Running 3h
mc/memcached-dev 1.6.22 Running 3h
mc/memcached-prod 1.6.22 Running 3h
mc/memcached-qa 1.6.22 Running 3h
Flag --output=wide is used to print additional information.
List command supports short names for each object types. You can use it like kubectl get <short-name>. Below are the short name for KubeDB objects:
- Memcached:
mc - DormantDatabase:
drmn
You can print labels with objects. The following command will list all Memcached with their corresponding labels.
$ kubectl get mc --show-labels
NAME VERSION STATUS AGE LABELS
memcached-demo 1.6.22 Running 2m kubedb=cli-demo
To print only object name, run the following command:
$ kubectl get all -o name
memcached/memcached-demo
memcached/memcached-dev
memcached/memcached-prod
memcached/memcached-qa
How to Describe Objects
kubectl dba describe command allows users to describe any KubeDB object. The following command will describe Memcached server memcached-demo with relevant information.
$ kubectl dba describe mc memcached-demo
Name: memcached-demo
Namespace: default
CreationTimestamp: Thu, 04 Oct 2018 11:58:57 +0600
Labels: kubedb=cli-demo
Annotations: <none>
Replicas: 3 total
Status: Running
Deployment:
Name: memcached-demo
CreationTimestamp: Thu, 04 Oct 2018 11:58:59 +0600
Labels: kubedb=cli-demo
app.kubernetes.io/name=memcacheds.kubedb.com
app.kubernetes.io/instance=memcached-demo
Annotations: deployment.kubernetes.io/revision=1
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: memcached-demo
Labels: kubedb=cli-demo
app.kubernetes.io/name=memcacheds.kubedb.com
app.kubernetes.io/instance=memcached-demo
Annotations: <none>
Type: ClusterIP
IP: 10.102.208.191
Port: db 11211/TCP
TargetPort: db/TCP
Endpoints: 172.17.0.4:11211,172.17.0.14:11211,172.17.0.6:11211
No Snapshots.
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Successful 2m Memcached operator Successfully created Service
Normal Successful 2m Memcached operator Successfully created StatefulSet
Normal Successful 2m Memcached operator Successfully created Memcached
Normal Successful 2m Memcached operator Successfully patched StatefulSet
Normal Successful 2m Memcached operator Successfully patched Memcached
kubectl dba describe command provides following basic information about a Memcached server.
- Deployment
- Service
- Monitoring system (If available)
To hide events on KubeDB object, use flag --show-events=false
To describe all Memcached objects in default namespace, use following command
kubectl dba describe mc
To describe all Memcached objects from every namespace, provide --all-namespaces flag.
kubectl dba describe mc --all-namespaces
To describe all KubeDB objects from every namespace, use the following command:
kubectl dba describe all --all-namespaces
You can also describe KubeDB objects with matching labels. The following command will describe all Memcached objects with specified labels from every namespace.
kubectl dba describe mc --all-namespaces --selector='group=dev'
To learn about various options of describe command, please visit here.
How to Edit Objects
kubectl edit command allows users to directly edit any KubeDB object. It will open the editor defined by KUBEDB_EDITOR, or EDITOR environment variables, or fall back to nano.
Let’s edit an existing running Memcached object to setup Monitoring. The following command will open Memcached memcached-demo in editor.
$ kubectl edit mc memcached-demo
#spec:
# monitor:
# agent: prometheus.io/builtin
memcached "memcached-demo" edited
Edit Restrictions
Various fields of a KubeDB object can’t be edited using edit command. The following fields are restricted from updates for all KubeDB objects:
- apiVersion
- kind
- metadata.name
- metadata.namespace
- status
If Deployment exists for a Memcached server, following fields can’t be modified as well.
- spec.nodeSelector
- spec.podTemplate.spec.nodeSelector
- spec.podTemplate.spec.env
For DormantDatabase, spec.origin can’t be edited using kubectl edit
How to Delete Objects
kubectl delete command will delete an object in default namespace by default unless namespace is provided. The following command will delete a Memcached memcached-dev in default namespace
$ kubectl delete memcached memcached-dev
memcached.kubedb.com "memcached-dev" deleted
You can also use YAML files to delete objects. The following command will delete a memcached using the type and name specified in memcached.yaml.
$ kubectl delete -f memcached-demo.yaml
memcached.kubedb.com "memcached-dev" deleted
kubectl delete command also takes input from stdin.
cat memcached-demo.yaml | kubectl delete -f -
To delete database with matching labels, use --selector flag. The following command will delete memcached with label memcached.app.kubernetes.io/instance=memcached-demo.
kubectl delete memcached -l memcached.app.kubernetes.io/instance=memcached-demo
Using Kubectl
You can use Kubectl with KubeDB objects like any other CRDs. Below are some common examples of using Kubectl with KubeDB objects.
# List objects
$ kubectl get memcached
$ kubectl get memcached.kubedb.com
# Delete objects
$ kubectl delete memcached <name>
Next Steps
- Learn how to use KubeDB to run a Memcached server here.
- Want to hack on KubeDB? Check our contribution guidelines.