kubernetes

Contents

kubernetes

https://www.katacoda.com/courses/kubernetes
deploy docker images in containers. Cluster has nodes. Nodes has pods/containers. Each cluster might correspond to a service.
Ingress, An API object that manages external access to the services in a cluster, typically HTTP. Ideas like reverse-proxy and load balancer.
minikube version # check version 1.2.0
minikube start

   1 minikube version
   2 # minikube version: v1.2.0
   3 minikube start
   4 # * minikube v1.2.0 on linux (amd64)
   5 # * Creating none VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
   6 # * Configuring environment for Kubernetes v1.15.0 on Docker 18.09.5
   7 #   - kubelet.resolv-conf=/run/systemd/resolve/resolv.conf
   8 # * Pulling images ...
   9 # * Launching Kubernetes ...
  10 # 
  11 # * Configuring local host environment ...
  12 # * Verifying: apiserver proxy etcd scheduler controller dns
  13 # * Done! kubectl is now configured to use "minikube"
  14

cluster details and health status

   1 kubectl cluster-info
   2 # Kubernetes master is running at https://172.17.0.30:8443
   3 # KubeDNS is running at https://172.17.0.30:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
   4 # 
   5 # To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
   6

get cluster nodes

   1 kubectl get nodes
   2 # NAME       STATUS   ROLES    AGE    VERSION
   3 # minikube   Ready    master   3m1s   v1.15.0
   4

Deploy containers

   1 # deploy container
   2 kubectl create deployment first-deployment --image=katacoda/docker-http-server
   3 # deployment.apps/first-deployment created
   4 # deploy container in cluster
   5 # check pods
   6 kubectl get pods
   7 # NAME                               READY   STATUS    RESTARTS   AGE
   8 # first-deployment-8cbf74484-s2fkl   1/1     Running   0          25s
   9 # expose deployment
  10 kubectl expose deployment first-deployment --port=80 --type=NodePort
  11 # service/first-deployment exposed
  12 
  13 kubectl get svc first-deployment
  14 # NAME               TYPE       CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
  15 # first-deployment   NodePort   10.98.246.87   <none>        80:31219/TCP   105s
  16 # do request to port 80 in cluster ip
  17 curl 10.98.246.87:80
  18 # <h1>This request was processed by host: first-deployment-8cbf74484-s2fkl</h1>
  19 # 
  20 curl host01:31219
  21 # <h1>This request was processed by host: first-deployment-8cbf74484-s2fkl</h1>
  22

dashboard

   1 minikube addons enable dashboard 
   2 #The Kubernetes dashboard allows you to view your applications
   3 # in a UI.
   4 # * dashboard was successfully enabled
   5 kubectl apply -f /opt/kubernetes-dashboard.yaml 
   6 # only in katacoda
   7 # service/kubernetes-dashboard-katacoda created
   8 # check progress
   9 kubectl get pods -n kube-system -w  #check progress
  10 # NAME                                    READY   STATUS    RESTARTS   AGE
  11 # coredns-5c98db65d4-b2kxm                1/1     Running   0          17m
  12 # coredns-5c98db65d4-mm567                1/1     Running   1          17m
  13 # etcd-minikube                           1/1     Running   0          16m
  14 # kube-addon-manager-minikube             1/1     Running   0          16m
  15 # kube-apiserver-minikube                 1/1     Running   0          16m
  16 # kube-controller-manager-minikube        1/1     Running   0          16m
  17 # kube-proxy-pngm9                        1/1     Running   0          17m
  18 # kube-scheduler-minikube                 1/1     Running   0          16m
  19 # kubernetes-dashboard-7b8ddcb5d6-xt5nt   1/1     Running   0          76s
  20 # storage-provisioner                     1/1     Running   0          17m
  21 
  22 # dashboard url https://2886795294-30000-kitek05.environments.katacoda.com/
  23 # how to launch a Single Node Kubernetes cluster. 
  24

Init master

   1 master $ kubeadm init --kubernetes-version $(kubeadm version -o short)
   2 [init] Using Kubernetes version: v1.14.0
   3 [preflight] Running pre-flight checks
   4 [preflight] Pulling images required for setting up a Kubernetes cluster
   5 [preflight] This might take a minute or two, depending on the speed of your internet connection
   6 [preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
   7 [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
   8 [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
   9 [kubelet-start] Activating the kubelet service
  10 [certs] Using certificateDir folder "/etc/kubernetes/pki"
  11 [certs] Generating "ca" certificate and key
  12 [certs] Generating "apiserver" certificate and key
  13 [certs] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 172.17.0.69]
  14 [certs] Generating "apiserver-kubelet-client" certificate and key
  15 [certs] Generating "front-proxy-ca" certificate and key
  16 [certs] Generating "front-proxy-client" certificate and key
  17 [certs] Generating "etcd/ca" certificate and key
  18 [certs] Generating "etcd/healthcheck-client" certificate and key
  19 [certs] Generating "apiserver-etcd-client" certificate and key
  20 [certs] Generating "etcd/server" certificate and key
  21 [certs] etcd/server serving cert is signed for DNS names [master localhost] and IPs [172.17.0.69 127.0.0.1 ::1]
  22 [certs] Generating "etcd/peer" certificate and key
  23 [certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [172.17.0.69 127.0.0.1 ::1]
  24 [certs] Generating "sa" key and public key
  25 [kubeconfig] Using kubeconfig folder "/etc/kubernetes"
  26 [kubeconfig] Writing "admin.conf" kubeconfig file
  27 [kubeconfig] Writing "kubelet.conf" kubeconfig file
  28 [kubeconfig] Writing "controller-manager.conf" kubeconfig file
  29 [kubeconfig] Writing "scheduler.conf" kubeconfig file
  30 [control-plane] Using manifest folder "/etc/kubernetes/manifests"
  31 [control-plane] Creating static Pod manifest for "kube-apiserver"
  32 [control-plane] Creating static Pod manifest for "kube-controller-manager"
  33 [control-plane] Creating static Pod manifest for "kube-scheduler"
  34 [etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
  35 [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
  36 [apiclient] All control plane components are healthy after 16.503433 seconds
  37 [upload-config] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system"Namespace
  38 [kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
  39 [upload-certs] Skipping phase. Please see --experimental-upload-certs
  40 [mark-control-plane] Marking the node master as control-plane by adding the label "node-role.kubernetes.io/master=''"
  41 [mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
  42 [bootstrap-token] Using token: xfvno5.q2xfb2m3nw7grdjm
  43 [bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
  44 [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
  45 [bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approveCSRs from a Node Bootstrap Token
  46 [bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
  47 [bootstrap-token] creating the "cluster-info" ConfigMap in the "kube-public" namespace
  48 [addons] Applied essential addon: CoreDNS
  49 [addons] Applied essential addon: kube-proxy
  50 
  51 Your Kubernetes control-plane has initialized successfully!
  52 
  53 To start using your cluster, you need to run the following as a regular user:
  54 
  55   mkdir -p $HOME/.kube
  56   sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  57   sudo chown $(id -u):$(id -g) $HOME/.kube/config
  58 
  59 You should now deploy a pod network to the cluster.
  60 Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  61   https://kubernetes.io/docs/concepts/cluster-administration/addons/
  62 
  63 Then you can join any number of worker nodes by running the following on each as root:
  64 
  65 kubeadm join 172.17.0.69:6443 --token xfvno5.q2xfb2m3nw7grdjm \
  66     --discovery-token-ca-cert-hash sha256:26d11c038d236967630d401747f210af9e3679fb1638e8b599a2da4cb98ab159

   1 # In master 
   2 mkdir -p $HOME/.kube
   3 pwd
   4 # /root
   5 sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
   6 sudo chown $(id -u):$(id -g) $HOME/.kube/config
   7 export KUBECONFIG=$HOME/.kube/config
   8 echo $KUBECONFIG/root/.kube/config

Deploy cni weaveworks - deploy a pod network to the cluster

Container Network Interface (CNI) defines how the different nodes and their workloads should communicate. Weave Net provides a network to connect all pods together, implementing the Kubernetes model. Kubernetes uses the Container Network Interface (CNI) to join pods onto Weave Net.

   1 # In master
   2 kubectl apply -f /opt/weave-kube
   3 # serviceaccount/weave-net created
   4 # clusterrole.rbac.authorization.k8s.io/weave-net created
   5 # clusterrolebinding.rbac.authorization.k8s.io/weave-net created
   6 # role.rbac.authorization.k8s.io/weave-net created
   7 # rolebinding.rbac.authorization.k8s.io/weave-net created
   8 # daemonset.extensions/weave-net created
   9 kubectl get pod -n kube-system
  10 # NAME                             READY   STATUS    RESTARTS   AGE
  11 # coredns-fb8b8dccf-b9rd7          1/1     Running   0          11m
  12 # coredns-fb8b8dccf-sfgbn          1/1     Running   0          11m
  13 # etcd-master                      1/1     Running   0          10m
  14 # kube-apiserver-master            1/1     Running   0          10m
  15 # kube-controller-manager-master   1/1     Running   0          10m
  16 # kube-proxy-l42wp                 1/1     Running   0          11m
  17 # kube-scheduler-master            1/1     Running   1          10m
  18 # weave-net-mcxml                  2/2     Running   0          84s
  19

Join cluster

   1 # In master
   2 kubeadm token list # check tokens
   3 # TOKEN                     TTL       EXPIRES                USAGES                   DESCRIPTION
   4 #                     EXTRA GROUPS
   5 # xfvno5.q2xfb2m3nw7grdjm   23h       2019-07-28T16:19:18Z   authentication,signing   The default bootstrap # token generated by 'kubeadm init'.   system:bootstrappers:kubeadm:default-node-token
   6

   1 # in node01
   2 # join cluster
   3 kubeadm join --discovery-token-unsafe-skip-ca-verification --token=xfvno5.q2xfb2m3nw7grdjm 172.17.0.69:6443
   4 # [preflight] Running pre-flight checks
   5 # [preflight] Reading configuration from the cluster...
   6 # [preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
   7 # [kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespace
   8 # [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
   9 # [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
  10 # [kubelet-start] Activating the kubelet service
  11 # [kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
  12 # 
  13 # This node has joined the cluster:
  14 # * Certificate signing request was sent to apiserver and a response was received.
  15 # * The Kubelet was informed of the new secure connection details.
  16 # 
  17 # Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
  18 # The --discovery-token-unsafe-skip-ca-verification tag is used to bypass the Discovery Token verification. 
  19 
  20 # in master
  21 kubectl get nodes
  22 # NAME     STATUS   ROLES    AGE    VERSION
  23 # master   Ready    master   17m    v1.14.0
  24 # node01   Ready    <none>   107s   v1.14.0                                                       
  25 # bootstrap token generated b
  26 
  27 # in node01
  28 kubectl get nodes 
  29 # The connection to the server localhost:8080 was refused - did you specify the right host or port
  30

Deploy container in cluster

   1 # In master
   2 kubectl create deployment http --image=katacoda/docker-http-server:latest
   3 # deployment.apps/http created
   4 kubectl get pods
   5 # NAME                    READY   STATUS    RESTARTS   AGE
   6 # http-7f8cbdf584-74pd9   1/1     Running   0          11s
   7 docker ps | grep http-server
   8 
   9 # In node01
  10 docker ps | grep http-serveradb3cde7f861        
  11 # katacoda/docker-http-server   "/app"                   
  12 # About a minute ago
  13 # Up About a minute                       k8s_docker-http-server_http-7f8cbdf584-74pd9_default_04a
  14 # 17065-b08d-11e9-bff1-0242ac110045_0
  15 
  16 # expose deployment in master
  17 kubectl get pods
  18 # NAME                    READY   STATUS    RESTARTS   AGE
  19 # http-7f8cbdf584-74pd9   1/1     Running   0          17m                                        bootstrap # token generated b
  20 kubectl expose deployment http  --port=80 --type=NodePort
  21 # service/http exposed
  22 
  23 kubectl get service http
  24 # NAME   TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
  25 # http   NodePort   10.101.65.149   <none>        80:30982/TCP   49s
  26 
  27 curl 10.101.65.149:80
  28 # <h1>This request was processed by host: http-7f8cbdf584-74pd9</h1>
  29 
  30 curl http://10.101.65.149
  31 # <h1>This request was processed by host: http-7f8cbdf584-74pd9</h1>
  32

Apply dashboard in cluster

Dashboard General-purpose web UI for Kubernetes clusters Dashboard Version: v1.10.0

   1 #  In master 
   2 kubectl apply -f dashboard.yaml
   3 # secret/kubernetes-dashboard-certs created
   4 # serviceaccount/kubernetes-dashboard created
   5 # role.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
   6 # rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
   7 # deployment.apps/kubernetes-dashboard created
   8 # service/kubernetes-dashboard created
   9 kubectl get pods -n kube-system
  10 # NAME                                    READY   STATUS              RESTARTS   AGEcoredns-fb8b8dccf-b9rd7                 # 1/1     Running             0          42mcoredns-fb8b8dccf-sfgbn                 1/1     Running             # 0          42m
  11 # etcd-master                             1/1     Running             0          41m
  12 # kube-apiserver-master                   1/1     Running             0          40m
  13 # kube-controller-manager-master          1/1     Running             0          40m
  14 # kube-proxy-gwrps                        1/1     Running             0          26m
  15 # kube-proxy-l42wp                        1/1     Running             0          42m
  16 # kube-scheduler-master                   1/1     Running             1          40m
  17 # kubernetes-dashboard-5f57845f9d-ls7q2   0/1     ContainerCreating   0          2s
  18 # weave-net-gww8b                         2/2     Running             0          26m
  19 # weave-net-mcxml                         2/2     Running             0          31m
  20

Create service account for dashboard

   1 cat <<EOF | kubectl create -f - 
   2 apiVersion: v1
   3 kind: ServiceAccount
   4 metadata:
   5   name: admin-user
   6   namespace: kube-system
   7 ---
   8 apiVersion: rbac.authorization.k8s.io/v1beta1
   9 kind: ClusterRoleBinding
  10 metadata:
  11   name: admin-user
  12 roleRef:
  13   apiGroup: rbac.authorization.k8s.io
  14   kind: ClusterRole
  15   name: cluster-admin
  16 subjects:
  17 - kind: ServiceAccount
  18   name: admin-user
  19   namespace: kube-system
  20 EOF
  21 
  22 # Get login token
  23 kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep admin-user | awk '{print $1}')
  24 
  25 When the dashboard was deployed, it used externalIPs to bind the service to port 8443. This makes the dashboard available to outside of the cluster and viewable at https://2886795335-8443-kitek05.environments.katacoda.com/
  26 
  27 # Use the admin-user token to access the dashboard.
  28 https://2886795335-8443-kitek05.environments.katacoda.com/#!/login
  29 # sign in using token
  30 eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJrdWJlLXN5c3RlbSIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VjcmV0Lm5hbWUiOiJhZG1pbi11c2VyLXRva2VuLXNzcTl4Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9zZXJ2aWNlLWFjY291bnQubmFtZSI6ImFkbWluLXVzZXIiLCJrdWJlcm5ldGVzLmlvL3NlcnZpY2VhY2NvdW50L3NlcnZpY2UtYWNjb3VudC51aWQiOiI2Y2RiNGZmMy1iMDkwLTExZTktYmZmMS0wMjQyYWMxMTAwNDUiLCJzdWIiOiJzeXN0ZW06c2VydmljZWFjY291bnQ6a3ViZS1zeXN0ZW06YWRtaW4tdXNlciJ9.R2OtDYxXaR0Pgluzq1m8FMZflF2tdYtJdG5XhkVC28vf1WkJu-Zo51I5ONUiK2WdBEMPw-N2PW_R9l6lak1clvlxfUSn777nThYSxhmR5pfxi6GmDlFo928KJvWVPDen1jrzAaQOEUZ1maOzPcnjKGpR-CRTgmYDnxZY84rqi68y0vfdn16ER8HeW-wkJ-hfGyUAhryk_ob1CUBjjbs-vefpaLcHLdrWNaKaFi1j5fCc_eJi10FpSTmuBsb04xgN0I17hkTlSw2fyOAj7LtC3pBDrK0nOdHCJkBEtsg89rkvLufYph5AFeoWQVKdW9JZH8BYS91BFla7pZnTwdBVeA
  31 
  32 https://2886795335-8443-kitek05.environments.katacoda.com/#!/overview?namespace=default

List services

   1 # In master
   2 kubectl get service
   3 # NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
   4 # http         NodePort    10.101.65.149   <none>        80:30982/TCP   17m
   5 # kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        56m
   6

Start containers using Kubectl

   1 minikube start # start kubernetes cluster and its components
   2 # * minikube v1.2.0 on linux (amd64)
   3 # * Creating none VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
   4 # * Configuring environment for Kubernetes v1.15.0 on Docker 18.09.5
   5 #   - kubelet.resolv-conf=/run/systemd/resolve/resolv.conf
   6 # * Pulling images ...
   7 # * Launching Kubernetes ...
   8 # * Configuring local host environment ...
   9 # * Verifying: apiserver proxy etcd
  10 # 
  11 #  scheduler controller dns
  12 # * Done! kubectl is now configured to use "minikube"
  13 kubectl get nodes
  14 # NAME       STATUS   ROLES    AGE    VERSION
  15 # minikube   Ready    master   2m2s   v1.15.0
  16 
  17 kubectl get service
  18 # NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
  19 # kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   2m18s
  20 # This deployment is issued to the Kubernetes master which launches the Pods and containers required. Kubectl run_ is similar to docker run but at a cluster 
  21 level.
  22 #  launch a deployment called http which will start a container based on the Docker Image katacoda/docker-http-server:latest.
  23 kubectl run http --image=katacoda/docker-http-server:latest --replicas=1
  24 # kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version.Use kubectl run --generator=run-pod/v1 or kubectl create instead.
  25 # deployment.apps/http created
  26 kubectl get deployments
  27 # NAME   READY   UP-TO-DATE   AVAILABLE   AGE
  28 # http   1/1     1            1           6s
  29 
  30 # you can describe the deployment process.
  31 kubectl describe deployment http
  32 
  33 # expose the container port 80 on the host 8000 binding to the external-ip of the host.
  34 kubectl expose deployment http --external-ip="172.17.0.13" --port=8000 --target-port=80
  35 # service/http exposed
  36 
  37 curl http://172.17.0.13:8000
  38 # <h1>This request was processed by host: http-5fcf9dd9cb-zfkkz</h1>
  39 
  40 kubectl get pods
  41 # NAME                    READY   STATUS    RESTARTS   AGE
  42 # http-5fcf9dd9cb-zfkkz   1/1     Running   0          3m26s
  43 
  44 kubectl get service
  45 # NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
  46 # http         ClusterIP   10.100.157.159   172.17.0.13   8000/TCP   57s
  47 # kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP    7m41s
  48 
  49 curl http://10.100.157.159:8000
  50 # <h1>This request was processed by host: http-5fcf9dd9cb-zfkkz</h1>
  51 
  52 kubectl run httpexposed --image=katacoda/docker-http-server:latest --replicas=1 --port=80 --host
  53 port=8001
  54 # kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version.
  55 # Use kubectl run --generator=run-pod/v1 or kubectl create instead.
  56 # deployment.apps/httpexposed created
  57 curl http://172.17.0.13:8001
  58 # <h1>This request was processed by host: httpexposed-569df5d86-rzzhb</h1>
  59 kubectl get svc
  60 # NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
  61 # http         ClusterIP   10.100.157.159   172.17.0.13   8000/TCP   3m50s
  62 # kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP    10m
  63 
  64 kubectl get pods
  65 # NAME                          READY   STATUS    RESTARTS   AGE
  66 # http-5fcf9dd9cb-zfkkz         1/1     Running   0          7m9s
  67 # httpexposed-569df5d86-rzzhb   1/1     Running   0          36s
  68 
  69 # Scaling the deployment will request Kubernetes to launch additional Pods.
  70 kubectl scale --replicas=3 deployment http
  71 # deployment.extensions/http scaled
  72 
  73 kubectl get pods # amount of pods for service http increased to 3
  74 # NAME                          READY   STATUS    RESTARTS   AGE
  75 # http-5fcf9dd9cb-fhljh         1/1     Running   0          31s
  76 # http-5fcf9dd9cb-wb2dh         1/1     Running   0          31s
  77 # http-5fcf9dd9cb-zfkkz         1/1     Running   0          9m27s
  78 # httpexposed-569df5d86-rzzhb   1/1     Running   0          2m54s
  79 
  80 # Once each Pod starts it will be added to the load balancer service.
  81 kubectl get service
  82 # NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
  83 # http         ClusterIP   10.100.157.159   172.17.0.13   8000/TCP   7m28s
  84 # kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP    14m
  85 
  86 kubectl describe svc http
  87 # Name:              http
  88 # Namespace:         defaultLabels:            run=httpAnnotations:       <none>
  89 # Selector:          run=httpType:              ClusterIPIP:                10.100.157.159
  90 # External IPs:      172.17.0.13
  91 # Port:              <unset>  8000/TCP
  92 # TargetPort:        80/TCP
  93 # Endpoints:         172.18.0.4:80,172.18.0.6:80,172.18.0.7:80
  94 # Session Affinity:  None
  95 # Events:            <none>
  96 
  97 curl http://172.17.0.13:8000
  98 # <h1>This request was processed by host: http-5fcf9dd9cb-wb2dh</h1>
  99 curl http://172.17.0.13:8000
 100 # <h1>This request was processed by host: http-5fcf9dd9cb-fhljh</h1>
 101 curl http://172.17.0.13:8000
 102 # <h1>This request was processed by host: http-5fcf9dd9cb-zfkkz</h1>
 103

Certified kubernetes application developer

https://www.katacoda.com/courses/kubernetes/first-steps-to-ckad-certification

   1 # In master 
   2 launch.sh
   3 # Waiting for Kubernetes to start...
   4 # Kubernetes started
   5 kubectl get nodes
   6 # NAME     STATUS   ROLES    AGE   VERSION
   7 # master   Ready    master   85m   v1.14.0
   8 # node01   Ready    <none>   85m   v1.14.0
   9 
  10 # deploy app
  11 kubectl create deployment examplehttpapp --image=katacoda/docker-http-server
  12 # deployment.apps/examplehttpapp created
  13 
  14 # view all deployments
  15 kubectl get deployments
  16 # NAME             READY   UP-TO-DATE   AVAILABLE   AGE
  17 # examplehttpapp   1/1     1            1           25s
  18 
  19 # A deployment will launch a set of Pods. A pod is a group of one or more containers deployed across the cluster. 
  20 kubectl get pods
  21 # NAME                            READY   STATUS    RESTARTS   AGE
  22 # examplehttpapp-58f66848-n7wn7   1/1     Running   0          71s
  23 
  24 # show pod ip and node where it is
  25 kubectl get pods -o wide
  26 # NAME                            READY   STATUS    RESTARTS   AGE    IP          NODE     NOMINATED NODE   # READINESS GATES
  27 # examplehttpapp-58f66848-n7wn7   1/1     Running   0          113s   10.44.0.2   node01   <none>           <none>
  28 
  29 # describe pod
  30 kubectl describe pod examplehttpapp-58f66848-n7wn7
  31 # Name:               examplehttpapp-58f66848-n7wn7
  32 # Namespace:          default
  33 # Priority:           0
  34 # PriorityClassName:  <none>
  35 # Node:               node01/172.17.0.24
  36 # Start Time:         Sat, 27 Jul 2019 17:59:35 +0000
  37 # Labels:             app=examplehttpapp
  38 #                     pod-template-hash=58f66848
  39 # Annotations:        <none>
  40 # Status:             Running
  41 # IP:                 10.44.0.2
  42 
  43 # List all namespaces with in the cluster with 
  44 kubectl get namespaces
  45 kubectl get ns
  46 
  47 # The namespaces can be used to filter queries to the available objects. 
  48 kubectl get pods -n kube-system
  49 
  50 kubectl create ns testns
  51 # namespace/testns created
  52 kubectl create deployment namespacedeg -n testns --image=katacoda/docker-http-server
  53 # deployment.apps/namespacedeg created
  54 kubectl get pods -n testns
  55 # NAME                            READY   STATUS    RESTARTS   AGE
  56 # namespacedeg-74dcc7dc64-wcxnj   1/1     Running   0          3s
  57 kubectl get pods -n testns -o wide
  58 # NAME                            READY   STATUS    RESTARTS   AGE   IP          NODE     NOMINATED NODE   READINESS GATES
  59 # namespacedeg-74dcc7dc64-wcxnj   1/1     Running   0          18s   10.44.0.3   node01   <none>           <none>
  60 
  61 # Kubectl can help scale the number of Pods running for a deployment, referred to as replicas.
  62 kubectl scale deployment examplehttpapp --replicas=5
  63 # deployment.extensions/examplehttpapp scaled
  64 kubectl get deployments -o wide
  65 # NAME             READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS           IMAGES                        SELECTOR
  66 # examplehttpapp   5/5     5            5           9m6s   docker-http-server   katacoda/docker-http-server   app=examplehttpapp
  67 kubectl get pods -o wide
  68 # NAME                            READY   STATUS    RESTARTS   AGE     IP          NODE     NOMINATED NODE   READINESS GATES
  69 # examplehttpapp-58f66848-cf6pl   1/1     Running   0          65s     10.44.0.6   node01   <none>           <none>
  70 # examplehttpapp-58f66848-lfrq4   1/1     Running   0          65s     10.44.0.5   node01   <none>           <none>
  71 # examplehttpapp-58f66848-n7wn7   1/1     Running   0          9m26s   10.44.0.2   node01   <none>           <none>
  72 # examplehttpapp-58f66848-snwl7   1/1     Running   0          65s     10.44.0.7   node01   <none>           <none>
  73 # examplehttpapp-58f66848-vd8db   1/1     Running   0          65s     10.44.0.4   node01   <none>           <none>
  74 
  75 # everything within Kubernetes is controllable as YAML.
  76 kubectl edit deployment examplehttpapp # opens vi/vim, changing the spec.replicas to 10 after saving the file increased the number of pods
  77 
  78 kubectl get nodes -o wide
  79 # NAME     STATUS   ROLES    AGE    VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION      CONTAINER-RUNTIME
  80 # master   Ready    master   102m   v1.14.0   172.17.0.19   <none>        Ubuntu 16.04.6 LTS   4.4.0-150-generic   docker://18.9.5
  81 # node01   Ready    <none>   102m   v1.14.0   172.17.0.24   <none>        Ubuntu 16.04.6 LTS   4.4.0-150-generic   docker://18.9.5
  82 
  83 # Image can be changed using the set image command, rollout
  84 # apply new image to the pods/containers
  85 kubectl --record=true set image deployment examplehttpapp docker-http-server=katacoda/docker-http-server:v2
  86 # deployment.extensions/examplehttpapp image updated
  87 kubectl rollout status deployment examplehttpapp
  88 # Waiting for deployment "examplehttpapp" rollout to finish: 1 out of 3 new replicas have been updated...
  89 # Waiting for deployment "examplehttpapp" rollout to finish: 1 out of 3 new replicas have been updated...
  90 # Waiting for deployment "examplehttpapp" rollout to finish: 1 out of 3 new replicas have been updated...
  91 # Waiting for deployment "examplehttpapp" rollout to finish: 2 out of 3 new replicas have been updated...
  92 # Waiting for deployment "examplehttpapp" rollout to finish: 2 out of 3 new replicas have been updated...
  93 # Waiting for deployment "examplehttpapp" rollout to finish: 2 out of 3 new replicas have been updated...
  94 # Waiting for deployment "examplehttpapp" rollout to finish: 1 old replicas are pending termination...
  95 # Waiting for deployment "examplehttpapp" rollout to finish: 1 old replicas are pending termination...
  96 deployment "examplehttpapp" successfully rolled out
  97 
  98 # rollback deployment
  99 kubectl rollout undo deployment examplehttpapp
 100 # deployment.extensions/examplehttpapp rolled back
 101 
 102 # The expose command will create a new service for a deployment. The port specifies the port of the application we want to available
 103 kubectl expose deployment examplehttpapp --port 80
 104 # service/examplehttpapp exposed
 105 kubectl get svc -o wide
 106 # NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE    SELECTOR
 107 # examplehttpapp   ClusterIP   10.103.93.196   <none>        80/TCP    13s    app=examplehttpapp
 108 # kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP   105m   <none>
 109 kubectl describe svc examplehttpapp
 110 # Name:              examplehttpapp
 111 # Namespace:         default
 112 # Labels:            app=examplehttpapp
 113 # Annotations:       <none>
 114 # Selector:          app=examplehttpapp
 115 # Type:              ClusterIP
 116 # IP:                10.103.93.196
 117 # Port:              <unset>  80/TCP
 118 # TargetPort:        80/TCP
 119 # Endpoints:         10.44.0.2:80,10.44.0.4:80,10.44.0.5:80
 120 # Session Affinity:  None
 121 # Events:            <none>
 122 
 123 # But how does Kubernetes know where to send traffic? That is managed by Labels. 
 124 # Each Object within Kubernetes can have a label attached, allowing Kubernetes to discover and use the configuration. 
 125 
 126 kubectl get services -l app=examplehttpapp -o go-template='{{(index .items 0).spec.clusterIP}}'
 127 kubectl get services
 128 # NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
 129 # examplehttpapp   ClusterIP   10.103.93.196   <none>        80/TCP    2m32s
 130 # kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP   107m
 131 
 132 kubectl get services -o wide
 133 # NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE     SELECTOR
 134 # examplehttpapp   ClusterIP   10.103.93.196   <none>        80/TCP    2m36s   app=examplehttpapp
 135 # kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP   107m    <none>
 136 
 137 # kubectl logs to to view the logs for Pods
 138 kubectl logs $(kubectl get pods -l app=examplehttpapp -o go-template='{{(index .items 0).metadata.name}}')
 139 # Web Server started. Listening on 0.0.0.0:80
 140 
 141 # view the CPU or Memory usage of a node or Pod
 142 kubectl top node
 143 # NAME     CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%
 144 # master   133m         3%     1012Mi          53%
 145 # node01   49m          1%     673Mi           17%
 146 kubectl top pod
 147 # NAME                            CPU(cores)   MEMORY(bytes)
 148 # examplehttpapp-58f66848-ctnml   0m           0Mi
 149 # examplehttpapp-58f66848-gljk9   1m           0Mi
 150 # examplehttpapp-58f66848-hfqts   1m           0Mi
 151

Shows mapping between services and pods

   1 kubectl get endpoints

Show events ordered by last timestamp ascending

   1 kubectl get events --sort-by='.lastTimestamp'