loeken
March 27, 2021
My road to self hosted kubernetes with k3s - kubectl
kubectl
kubectl is a command line tool you can use to interact with the kubernetes api server.
we already installed minikube which includes kubectl and already creates a default config for us. the default config can be found in ~/.kube/config
you can extend your ~/.kube/config and add further clusters/users/contexts this allows us to define different credentials for different clusters and helps us to switch between various clusters easily. here is an example of a “REDACTED” ~/.kube/config and how i switch my context from using the minikube cluster to using my baremetall cluster
❯ cat ~/.kube/config
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: REDACTED
server: https://REDACTED:6443
name: baremetall
- cluster:
certificate-authority-data: REDACTED
server: https://REDACTED:6443
name: enso
- cluster:
certificate-authority-data: REDACTED
server: https://REDACTED:6443
name: ime
- cluster:
certificate-authority-data: REDACTED
server: https://REDACTED:6443
name: jp
- cluster:
certificate-authority-data: REDACTED
server: https://REDACTED:8443
name: minikube
contexts:
- context:
cluster: baremetall
user: baremetall
name: baremetall
- context:
cluster: enso
user: enso
name: enso
- context:
cluster: ime
user: ime
name: ime
- context:
cluster: jp
user: jp
name: jp
- context:
cluster: minikube
namespace: default
user: minikube
name: minikube
current-context: enso
kind: Config
preferences: {}
users:
- name: baremetall
user:
client-certificate-data: REDACTED
client-key-data: REDACTED
- name: enso
user:
client-certificate-data: REDACTED
client-key-data: REDACTED
- name: ime
user:
client-certificate-data: REDACTED
client-key-data: REDACTED
- name: jp
user:
client-certificate-data: REDACTED
- name: minikube
user:
client-certificate-data: REDACTED
client-key-data: REDACTED
❯ kubectl get nodes
NAME STATUS ROLES AGE VERSION
minikube Ready control-plane,master 4d23h v1.20.2
❯ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
baremetall baremetall baremetall
enso enso enso
ime ime ime
jp jp jp
* minikube minikube minikube default
❯ kubectl config use-context baremetall
Switched to context "baremetall".
❯ kubectl get nodes
NAME STATUS ROLES AGE VERSION
k3s-node-01 Ready etcd,master 106d v1.20.2
k3s-node-02 Ready etcd,master 106d v1.20.2
k3s-node-03 Ready etcd,master 106d v1.20.2
the rest of the commands all follow a simple structure you can use kubectl help to list all commands
❯ kubectl help
kubectl controls the Kubernetes cluster manager.
Find more information at: https://kubernetes.io/docs/reference/kubectl/overview/
Basic Commands (Beginner):
create Create a resource from a file or from stdin.
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
run Run a particular image on the cluster
set Set specific features on objects
Basic Commands (Intermediate):
explain Documentation of resources
get Display one or many resources
edit Edit a resource on the server
delete Delete resources by filenames, stdin, resources and names, or by resources and label selector
Deploy Commands:
rollout Manage the rollout of a resource
scale Set a new size for a Deployment, ReplicaSet or Replication Controller
autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController
Cluster Management Commands:
certificate Modify certificate resources.
cluster-info Display cluster info
top Display Resource (CPU/Memory/Storage) usage.
cordon Mark node as unschedulable
uncordon Mark node as schedulable
drain Drain node in preparation for maintenance
taint Update the taints on one or more nodes
Troubleshooting and Debugging Commands:
describe Show details of a specific resource or group of resources
logs Print the logs for a container in a pod
attach Attach to a running container
exec Execute a command in a container
port-forward Forward one or more local ports to a pod
proxy Run a proxy to the Kubernetes API server
cp Copy files and directories to and from containers.
auth Inspect authorization
debug Create debugging sessions for troubleshooting workloads and nodes
Advanced Commands:
diff Diff live version against would-be applied version
apply Apply a configuration to a resource by filename or stdin
patch Update field(s) of a resource
replace Replace a resource by filename or stdin
wait Experimental: Wait for a specific condition on one or many resources.
kustomize Build a kustomization target from a directory or a remote url.
Settings Commands:
label Update the labels on a resource
annotate Update the annotations on a resource
completion Output shell completion code for the specified shell (bash or zsh)
Other Commands:
api-resources Print the supported API resources on the server
api-versions Print the supported API versions on the server, in the form of "group/version"
config Modify kubeconfig files
plugin Provides utilities for interacting with plugins.
version Print the client and server version information
Usage:
kubectl [flags] [options]
Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
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