$ kubectl create deployment hello-node --image=gcr.io/hello-minikube-zero-install/hello-node

deployment.apps/hello-node created

$ kubectl get deployments

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
hello-node   1/1     1            1           19s

$ kubectl get pods
NAME                          READY   STATUS    RESTARTS   AGE
hello-node-55b49fb9f8-bkmnb   1/1     Running   0          43s


$ kubectl get events

LAST SEEN   TYPE     REASON                    OBJECT                             MESSAGE

94s         Normal   Scheduled                 pod/hello-node-55b49fb9f8-bkmnb    Successfully assigned default/hello-node-55b49fb9f8-bkmnb to minikube
92s         Normal   Pulling                   pod/hello-node-55b49fb9f8-bkmnb    Pulling image "gcr.io/hello-minikube-zero-install/hello-node"
91s         Normal   Pulled                    pod/hello-node-55b49fb9f8-bkmnb    Successfully pulled image "gcr.io/hello-minikube-zero-install/hello-node"
90s         Normal   Created                   pod/hello-node-55b49fb9f8-bkmnb    Created container hello-node
90s         Normal   Started                   pod/hello-node-55b49fb9f8-bkmnb    Started container hello-node
94s         Normal   SuccessfulCreate          replicaset/hello-node-55b49fb9f8   Created pod: hello-node-55b49fb9f8-bkmnb
94s         Normal   ScalingReplicaSet         deployment/hello-node              Scaled up replica set hello-node-55b49fb9f8 to 1
4m34s       Normal   NodeHasSufficientMemory   node/minikube                      Node minikube status is now: NodeHasSufficientMemory
4m34s       Normal   NodeHasNoDiskPressure     node/minikube                      Node minikube status is now: NodeHasNoDiskPressure
4m34s       Normal   NodeHasSufficientPID      node/minikube                      Node minikube status is now: NodeHasSufficientPID
4m11s       Normal   RegisteredNode            node/minikube                      Node minikube event: Registered Node minikube in Controller
4m6s        Normal   Starting                  node/minikube                      Starting kube-proxy.

$ kubectl config view

apiVersion: v1
clusters:
- cluster:
    certificate-authority: /root/.minikube/ca.crt
    server: https://172.17.0.27:8443
  name: minikube
contexts:
- context:
    cluster: minikube
    user: minikube
  name: minikube
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
  user:
    client-certificate: /root/.minikube/client.crt
    client-key: /root/.minikube/client.key

# nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

$ kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx-deployment created
$ kubectl get events
$ kubectl get pods
$ kubectl delete deployment nginx-deployment
deployment.extensions "nginx-deployment" deleted

$ kubectl get deployments

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
hello-node   1/1     1            1           4m16s

$ kubectl delete deployment hello-node
deployment.extensions "hello-node" deleted

$ kubectl get deployments
No resources found.

$ kubectl get pods
No resources found.

# This script is the modified version from k8s documentation
RELEASE="$(curl -sSL https://dl.k8s.io/release/stable.txt)"

mkdir -p /usr/bin
cd /usr/bin

curl -L --remote-name-all https://storage.googleapis.com/kubernetes-release/release/${RELEASE}/bin/linux/amd64/{kubeadm,kubelet,kubectl}
chmod +x {kubeadm,kubelet,kubectl}

curl -sSL "https://raw.githubusercontent.com/kubernetes/kubernetes/${RELEASE}/build/debs/kubelet.service" > /etc/systemd/system/kubelet.service

mkdir -p /etc/systemd/system/kubelet.service.d

curl -sSL "https://raw.githubusercontent.com/kubernetes/kubernetes/${RELEASE}/build/debs/10-kubeadm.conf" > /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

[root@10 ~]# swapoff -a
[root@10 ~]# kubeadm init
[init] Using Kubernetes version: v1.15.3
[preflight] Running pre-flight checks
	[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly
	[WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [10.0.2.15 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.2.15]
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [10.0.2.15 localhost] and IPs [10.0.2.15 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [10.0.2.15 localhost] and IPs [10.0.2.15 127.0.0.1 ::1]
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 20.014010 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node 10.0.2.15 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node 10.0.2.15 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: n2e7ii.lp571oh88qidwzdj
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 10.0.2.15:6443 --token n2e7ii.lp571oh88qidwzdj \
    --discovery-token-ca-cert-hash sha256:0957baa4cdea8fda244c159cf2a038a2afe2c0b20fb922014472c5c7918dac81

[root@10 ~]# service kubelet status
Redirecting to /bin/systemctl status kubelet.service
● kubelet.service - kubelet: The Kubernetes Node Agent
   Loaded: loaded (/etc/systemd/system/kubelet.service; enabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/kubelet.service.d
           └─10-kubeadm.conf
   Active: active (running) since zo 2019-09-01 21:04:42 CEST; 1min 9s ago
     Docs: http://kubernetes.io/docs/
 Main PID: 4682 (kubelet)
   CGroup: /system.slice/kubelet.service
           └─4682 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --c...

sep 01 21:05:35 10.0.2.15 kubelet[4682]: E0901 21:05:35.780354    4682 summary_sys_containers.go:47] Failed to get system container stats for ...
sep 01 21:05:35 10.0.2.15 kubelet[4682]: E0901 21:05:35.780463    4682 summary_sys_containers.go:47] Failed to get system container stats for ...
sep 01 21:05:37 10.0.2.15 kubelet[4682]: W0901 21:05:37.277274    4682 cni.go:213] Unable to update cni config: No networks found in /...ni/net.d
sep 01 21:05:40 10.0.2.15 kubelet[4682]: E0901 21:05:40.725221    4682 kubelet.go:2169] Container runtime network not ready: NetworkRe...tialized
sep 01 21:05:42 10.0.2.15 kubelet[4682]: W0901 21:05:42.277894    4682 cni.go:213] Unable to update cni config: No networks found in /...ni/net.d
sep 01 21:05:45 10.0.2.15 kubelet[4682]: E0901 21:05:45.728937    4682 kubelet.go:2169] Container runtime network not ready: NetworkRe...tialized
sep 01 21:05:45 10.0.2.15 kubelet[4682]: E0901 21:05:45.813742    4682 summary_sys_containers.go:47] Failed to get system container stats for ...
sep 01 21:05:45 10.0.2.15 kubelet[4682]: E0901 21:05:45.813868    4682 summary_sys_containers.go:47] Failed to get system container stats for ...
sep 01 21:05:47 10.0.2.15 kubelet[4682]: W0901 21:05:47.278690    4682 cni.go:213] Unable to update cni config: No networks found in /...ni/net.d
sep 01 21:05:50 10.0.2.15 kubelet[4682]: E0901 21:05:50.733668    4682 kubelet.go:2169] Container runtime network not ready: NetworkRe...tialized
Hint: Some lines were ellipsized, use -l to show in full.

#run the following as a regular user, to start using the cluster
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

[root@10 ~]# kubectl get nodes
NAME        STATUS     ROLES    AGE     VERSION
10.0.2.15   NotReady   master   6m38s   v1.15.3

[root@10 ~]# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
serviceaccount/weave-net created
clusterrole.rbac.authorization.k8s.io/weave-net created
clusterrolebinding.rbac.authorization.k8s.io/weave-net created
role.rbac.authorization.k8s.io/weave-net created
rolebinding.rbac.authorization.k8s.io/weave-net created
daemonset.extensions/weave-net created

# kubernetes master is now in Ready status after deploying weave-net
[root@10 ~]# kubectl get nodes
NAME        STATUS   ROLES    AGE   VERSION
10.0.2.15   Ready    master   4d    v1.15.3

[root@10 ~]# kubectl get pods -n kube-system
NAME                                READY   STATUS    RESTARTS   AGE
coredns-5644d7b6d9-9gp2m            0/1     Running   0          23m
coredns-5644d7b6d9-x5f9f            0/1     Running   0          23m
etcd-10.0.2.15                      1/1     Running   0          22m
kube-apiserver-10.0.2.15            1/1     Running   0          22m
kube-controller-manager-10.0.2.15   1/1     Running   0          22m
kube-proxy-xw6mq                    1/1     Running   0          23m
kube-scheduler-10.0.2.15            1/1     Running   0          22m
weave-net-8hmqc                     2/2     Running   0          2m6s

[root@10 ~]# kubectl get pods -A
NAMESPACE     NAME                                READY   STATUS    RESTARTS   AGE
kube-system   coredns-5644d7b6d9-9gp2m            0/1     Running   0          23m
kube-system   coredns-5644d7b6d9-x5f9f            0/1     Running   0          23m
kube-system   etcd-10.0.2.15                      1/1     Running   0          22m
kube-system   kube-apiserver-10.0.2.15            1/1     Running   0          22m
kube-system   kube-controller-manager-10.0.2.15   1/1     Running   0          22m
kube-system   kube-proxy-xw6mq                    1/1     Running   0          23m
kube-system   kube-scheduler-10.0.2.15            1/1     Running   0          22m
kube-system   weave-net-8hmqc                     2/2     Running   0          2m9s

[root@10 ~]# kubectl get componentstatuses
NAME                 STATUS    MESSAGE             ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-0               Healthy   {"health":"true"}

[root@10 ~]# kubectl get events
LAST SEEN   TYPE     REASON                    OBJECT           MESSAGE
4d          Normal   NodeHasSufficientMemory   node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasSufficientMemory
4d          Normal   NodeHasNoDiskPressure     node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasNoDiskPressure
4d          Normal   NodeHasSufficientPID      node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasSufficientPID
4d          Normal   RegisteredNode            node/10.0.2.15   Node 10.0.2.15 event: Registered Node 10.0.2.15 in Controller
4d          Normal   Starting                  node/10.0.2.15   Starting kube-proxy.
38m         Normal   Starting                  node/10.0.2.15   Starting kubelet.
38m         Normal   NodeHasSufficientMemory   node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasSufficientMemory
38m         Normal   NodeHasNoDiskPressure     node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasNoDiskPressure
38m         Normal   NodeHasSufficientPID      node/10.0.2.15   Node 10.0.2.15 status is now: NodeHasSufficientPID
38m         Normal   NodeAllocatableEnforced   node/10.0.2.15   Updated Node Allocatable limit across pods
38m         Normal   Starting                  node/10.0.2.15   Starting kube-proxy.
38m         Normal   RegisteredNode            node/10.0.2.15   Node 10.0.2.15 event: Registered Node 10.0.2.15 in Controller
12m         Normal   NodeReady                 node/10.0.2.15   Node 10.0.2.15 status is now: NodeReady

[root@10 kubernetes]# tree /etc/kubernetes
/etc/kubernetes
├── admin.conf
├── controller-manager.conf
├── kubelet.conf
├── manifests
│   ├── etcd.yaml
│   ├── kube-apiserver.yaml
│   ├── kube-controller-manager.yaml
│   └── kube-scheduler.yaml
├── pki
│   ├── apiserver.crt
│   ├── apiserver-etcd-client.crt
│   ├── apiserver-etcd-client.key
│   ├── apiserver.key
│   ├── apiserver-kubelet-client.crt
│   ├── apiserver-kubelet-client.key
│   ├── ca.crt
│   ├── ca.key
│   ├── etcd
│   │   ├── ca.crt
│   │   ├── ca.key
│   │   ├── healthcheck-client.crt
│   │   ├── healthcheck-client.key
│   │   ├── peer.crt
│   │   ├── peer.key
│   │   ├── server.crt
│   │   └── server.key
│   ├── front-proxy-ca.crt
│   ├── front-proxy-ca.key
│   ├── front-proxy-client.crt
│   ├── front-proxy-client.key
│   ├── sa.key
│   └── sa.pub
└── scheduler.conf

3 directories, 30 files

[root@10 kubernetes]# docker images
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-proxy                v1.15.3             232b5c793146        13 days ago         82.4 MB
k8s.gcr.io/kube-apiserver            v1.15.3             5eb2d3fc7a44        13 days ago         207 MB
k8s.gcr.io/kube-scheduler            v1.15.3             703f9c69a5d5        13 days ago         81.1 MB
k8s.gcr.io/kube-controller-manager   v1.15.3             e77c31de5547        13 days ago         159 MB
k8s.gcr.io/coredns                   1.3.1               eb516548c180        7 months ago        40.3 MB
k8s.gcr.io/etcd                      3.3.10              2c4adeb21b4f        9 months ago        258 MB
k8s.gcr.io/pause                     3.1                 da86e6ba6ca1        20 months ago       742 kB

[root@10 ~]# kubeadm reset
[reset] Reading configuration from the cluster...
[reset] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[reset] WARNING: Changes made to this host by 'kubeadm init' or 'kubeadm join' will be reverted.
[reset] Are you sure you want to proceed? [y/N]: y
[preflight] Running pre-flight checks
[reset] Removing info for node "10.0.2.15" from the ConfigMap "kubeadm-config" in the "kube-system" Namespace
W0901 11:56:16.802756   29062 removeetcdmember.go:61] [reset] failed to remove etcd member: error syncing endpoints with etc: etcdclient: no available endpoints
.Please manually remove this etcd member using etcdctl
[reset] Stopping the kubelet service
[reset] Unmounting mounted directories in "/var/lib/kubelet"
[reset] Deleting contents of config directories: [/etc/kubernetes/manifests /etc/kubernetes/pki]
[reset] Deleting files: [/etc/kubernetes/admin.conf /etc/kubernetes/kubelet.conf /etc/kubernetes/bootstrap-kubelet.conf /etc/kubernetes/controller-manager.conf /etc/kubernetes/scheduler.conf]
[reset] Deleting contents of stateful directories: [/var/lib/etcd /var/lib/kubelet /etc/cni/net.d /var/lib/dockershim /var/run/kubernetes]

The reset process does not reset or clean up iptables rules or IPVS tables.
If you wish to reset iptables, you must do so manually.
For example:
iptables -F && iptables -t nat -F && iptables -t mangle -F && iptables -X

If your cluster was setup to utilize IPVS, run ipvsadm --clear (or similar)
to reset your system's IPVS tables.

The reset process does not clean your kubeconfig files and you must remove them manually.
Please, check the contents of the $HOME/.kube/config file.
[root@10 ~]#

# swapoff -a
# systemctl start kubelet
# systemctl status kubelet

# This command will create a new token and display the connection string
[root@10 ~]# kubeadm token create --print-join-command
kubeadm join 10.0.2.15:6443 --token 1clhim.pk9teustr2v1gnu2     --discovery-token-ca-cert-hash sha256:efe18b97c7a320e7173238af7126e33ebe76f3877255c8f9aa055f292dbf3755

# Other toke commands
kubeadm token list
kubeadm token delete <TOKEN>

# vi /var/log/messages
Sep  1 20:57:25 localhost kubelet: F0901 20:57:25.706063    2874 server.go:198] failed to load Kubelet config file /var/lib/kubelet/config.yaml, error failed to read kubelet config file "/var/lib/kubelet/config.yaml", error: open /var/lib/kubelet/config.yaml: no such file or directory
Sep  1 20:57:25 localhost systemd: kubelet.service: main process exited, code=exited, status=255/n/a
Sep  1 20:57:25 localhost systemd: Unit kubelet.service entered failed state.
Sep  1 20:57:25 localhost systemd: kubelet.service failed.
Sep  1 20:57:35 localhost systemd: kubelet.service holdoff time over, scheduling restart.
Sep  1 20:57:35 localhost systemd: Stopped kubelet: The Kubernetes Node Agent.
Sep  1 20:57:35 localhost systemd: Started kubelet: The Kubernetes Node Agent.
Sep  1 20:57:35 localhost kubelet: F0901 20:57:35.968939    2882 server.go:198] failed to load Kubelet config file /var/lib/kubelet/config.yaml, error failed to read kubelet config file "/var/lib/kubelet/config.yaml", error: open /var/lib/kubelet/config.yaml: no such file or directory
Sep  1 20:57:35 localhost systemd: kubelet.service: main process exited, code=exited, status=255/n/a
Sep  1 20:57:35 localhost systemd: Unit kubelet.service entered failed state.
Sep  1 20:57:35 localhost systemd: kubelet.service failed.

# Set go path, kind path and KUBECONFIG path

export PATH=$PATH:$HOME/go/bin:$HOME/k8s/bin
kind get kubeconfig-path)
# output: /home/sriram/.kube/kind-config-kind
export KUBECONFIG="$(kind get kubeconfig-path)"

sriram@sriram-Inspiron-5567:~$ kind create cluster
Creating cluster "kind" ...
 ✓ Ensuring node image (kindest/node:v1.15.0) 🖼 
 ✓ Preparing nodes 📦 
 ✓ Creating kubeadm config 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Cluster creation complete. You can now use the cluster with:

export KUBECONFIG="$(kind get kubeconfig-path --name="kind")"
kubectl cluster-info

kind create cluster
 kubectl cluster-info
 Kubernetes master is running at https://localhost:37933
 KubeDNS is running at https://localhost:37933/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

# To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

kind delete cluster
Deleting cluster "kind" ...
$KUBECONFIG is still set to use /home/sriram/.kube/kind-config-kind even though that file has been deleted, remember to unset it

$ kubectl version

Client Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.2", GitCommit:"f6278300bebbb750328ac16ee6dd3aa7d3549568", GitTreeState:"clean", BuildDate:"2019-08-05T09:23:26Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}

Server Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.0", GitCommit:"e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529", GitTreeState:"clean", BuildDate:"2019-06-19T16:32:14Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}

$ kubectl cluster-info
Kubernetes master is running at https://172.17.0.45:8443
KubeDNS is running at https://172.17.0.45:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

$ kubectl get nodes
NAME       STATUS   ROLES    AGE   VERSION
minikube   Ready    master   11m   v1.15.0

# list nodes with more information
$ kubectl get nodes -o=wide
NAME       STATUS   ROLES    AGE   VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE              KERNEL-VERSION   CONTAINER-RUNTIME
minikube   Ready    master   13m   v1.15.0   10.0.2.15     <none>        Buildroot 2018.05.3   4.15.0           docker://18.9.6

kubectl create namespace dev

Kubectl create configmap \
 <config-name> --from-literal=<key>=<value>

(or)
Kubectl create configmap \
 <config-name> --from-file=<path_to_file>

Kubectl create configmap \
app-color-config –from-literal=APP_COLOR=blue \
--from-literal=APP_MOD=prod

Kubectl create configmap \
app-config  --from-file=app-config.properties

sriram@sriram-Inspiron-5567:~/k8s$ minikube start
😄  minikube v1.2.0 on linux (amd64)
💿  Downloading Minikube ISO ...
 129.33 MB / 129.33 MB [============================================] 100.00% 0s
🔥  Creating virtualbox VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
🐳  Configuring environment for Kubernetes v1.15.0 on Docker 18.09.6
💾  Downloading kubeadm v1.15.0
💾  Downloading kubelet v1.15.0
🚜  Pulling images ...
🚀  Launching Kubernetes ... 
⌛  Verifying: apiserver proxy etcd scheduler controller dns
🏄  Done! kubectl is now configured to use "minikube"

$ minikube status
host: Running
kubelet: Running
apiserver: Running
kubectl: Correctly Configured: pointing to minikube-vm at 192.168.99.100

$ minikube service list

|-------------|------------|--------------|
|  NAMESPACE  |    NAME    |     URL      |
|-------------|------------|--------------|
| default     | kubernetes | No node port |
| kube-system | kube-dns   | No node port |
|-------------|------------|--------------|

$ minikube stop
✋  Stopping "minikube" in virtualbox ...
🛑  "minikube" stopped.

$ minikube status
host: Stopped
kubelet:
apiserver:
kubectl:

sriram@sriram-Inspiron-5567:~/k8s$ minikube start
😄  minikube v1.2.0 on linux (amd64)
💡  Tip: Use 'minikube start -p <name>' to create a new cluster, or 'minikube delete' to delete this one.
🔄  Restarting existing virtualbox VM for "minikube" ...
⌛  Waiting for SSH access ...
🐳  Configuring environment for Kubernetes v1.15.0 on Docker 18.09.6
🔄  Relaunching Kubernetes v1.15.0 using kubeadm ... 
⌛  Verifying: apiserver proxy etcd scheduler controller dns
🏄  Done! kubectl is now configured to use "minikube"

$ minikube addons enable metrics-server
✅  metrics-server was successfully enabled

sriram@sriram-Inspiron-5567:~/k8s$ kubectl get apiservices
NAME                                   SERVICE                      AVAILABLE   AGE
v1.                                    Local                        True        31m
v1.apps                                Local                        True        31m
v1.authentication.k8s.io               Local                        True        31m
v1.authorization.k8s.io                Local                        True        31m
v1.autoscaling                         Local                        True        31m
v1.batch                               Local                        True        31m
v1.coordination.k8s.io                 Local                        True        31m
v1.networking.k8s.io                   Local                        True        31m
v1.rbac.authorization.k8s.io           Local                        True        31m
v1.scheduling.k8s.io                   Local                        True        31m
v1.storage.k8s.io                      Local                        True        31m
v1beta1.admissionregistration.k8s.io   Local                        True        31m
v1beta1.apiextensions.k8s.io           Local                        True        31m
v1beta1.apps                           Local                        True        31m
v1beta1.authentication.k8s.io          Local                        True        31m
v1beta1.authorization.k8s.io           Local                        True        31m
v1beta1.batch                          Local                        True        31m
v1beta1.certificates.k8s.io            Local                        True        31m
v1beta1.coordination.k8s.io            Local                        True        31m
v1beta1.events.k8s.io                  Local                        True        31m
v1beta1.extensions                     Local                        True        31m
v1beta1.metrics.k8s.io                 kube-system/metrics-server   True        95s
v1beta1.networking.k8s.io              Local                        True        31m
v1beta1.node.k8s.io                    Local                        True        31m
v1beta1.policy                         Local                        True        31m
v1beta1.rbac.authorization.k8s.io      Local                        True        31m
v1beta1.scheduling.k8s.io              Local                        True        31m
v1beta1.storage.k8s.io                 Local                        True        31m
v1beta2.apps                           Local                        True        31m
v2beta1.autoscaling                    Local                        True        31m
v2beta2.autoscaling                    Local                        True        31m

export HTTP_PROXY=http://<proxy hostname:port>
export HTTPS_PROXY=https://<proxy hostname:port>
export NO_PROXY=localhost,127.0.0.1,10.96.0.0/12,192.168.99.0/24,192.168.39.0/24

minikube start

$ kubectl describe pods

Name:           kubernetes-bootcamp-5b48cfdcbd-5ddlwNamespace:      defaultPriority:       0

Node:           minikube/172.17.0.90
Start Time:     Mon, 26 Aug 2019 11:54:05 +0000
Labels:         pod-template-hash=5b48cfdcbd
                run=kubernetes-bootcamp

Annotations:    <none>

Status:         Running
IP:             172.18.0.5
Controlled By:  ReplicaSet/kubernetes-bootcamp-5b48cfdcbd

Containers:

  kubernetes-bootcamp:
    Container ID:   docker://016f25827984c14dc74e5cbaafe43b0fb77b20b8838b5818d1e9a90376b8ad5d
    Image:          gcr.io/google-samples/kubernetes-bootcamp:v1
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:0d6b8ee63bb57c5f5b6156f446b3bc3b3c143d233037f3a2f00e279c8fcc64af
    Port:           8080/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Mon, 26 Aug 2019 11:54:06 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-5wbkl (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-5wbkl:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-5wbkl
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age    From               Message
  ----    ------     ----   ----               -------
  Normal  Scheduled  6m58s  default-scheduler  Successfully assigned default/kubernetes-bootcamp-5b48cfdcbd-5ddlw to minikube
  Normal  Pulled     6m57s  kubelet, minikube  Container image "gcr.io/google-samples/kubernetes-bootcamp:v1" already present on machine
  Normal  Created    6m57s  kubelet, minikube  Created container kubernetes-bootcamp
  Normal  Started    6m57s  kubelet, minikube  Started container kubernetes-bootcamp

apiVersion: v1
kind: Pod
metadata:
  name: label-demo
  labels:
    environment: production
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    ports:
    - containerPort: 80

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  username: User
  password: **********

$ kubectl apply -f ./secret.yaml
$ kubectl get secrets
NAME                  TYPE                                  DATA   AGE
default-token-prh24   kubernetes.io/service-account-token   3      27m
mysecret              Opaque                                2      14m

$ export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}')

$ echo $POD_NAME
kubernetes-bootcamp-5b48cfdcbd-5ddlw

$ kubectl exec $POD_NAME env

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=kubernetes-bootcamp-5b48cfdcbd-5ddlw
KUBERNETES_SERVICE_HOST=10.96.0.1
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
NPM_CONFIG_LOGLEVEL=info
NODE_VERSION=6.3.1
HOME=/root

# Start a bash session in the Pod’s container:
 ## name of the container can be omitted if we only have a single container in the Pod

kubectl exec -ti $POD_NAME bash