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
get cluster nodes
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
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 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
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
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
k3s - Lightweight Kubernetes
K3S works great from something as small as a Raspberry Pi to an AWS a1.4xlarge 32GiB server. Download k3s - latest release, x86_64, ARMv7, and ARM64 are supported Situations where a PhD in k8s clusterology is infeasible
1 curl -sfL https://get.k3s.io | sh -
2 sudo curl -sfL https://get.k3s.io | sh -
3 # [INFO] Finding latest release
4 # [INFO] Using v1.17.0+k3s.1 as release
5 # [INFO] Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.0+k3s.1/sha256sum-amd64.txt
6 # [INFO] Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.0+k3s.1/k3s
7 # [INFO] Verifying binary download
8 # [INFO] Installing k3s to /usr/local/bin/k3s
9 # [INFO] Creating /usr/local/bin/kubectl symlink to k3s
10 # [INFO] Creating /usr/local/bin/crictl symlink to k3s
11 # [INFO] Creating /usr/local/bin/ctr symlink to k3s
12 # [INFO] Creating killall script /usr/local/bin/k3s-killall.sh
13 # [INFO] Creating uninstall script /usr/local/bin/k3s-uninstall.sh
14 # [INFO] env: Creating environment file /etc/systemd/system/k3s.service.env
15 # [INFO] systemd: Creating service file /etc/systemd/system/k3s.service
16 # [INFO] systemd: Enabling k3s unit
17 # Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
18 # [INFO] systemd: Starting k3s
19 # as root
20 k3s kubectl cluster-info
21 kubectl create deployment springboot-test --image=vbodocker/springboot-test:latest
22 kubectl expose deployment springboot-test --port=8000 --target-port=8080 --type=NodePort
23 kubectl get services
24 IP_SPRINGBOOT=$(kubectl get services | grep springboot | awk '//{print $3}')
25 curl http://$IP_SPRINGBOOT:8000/dummy
26 # list containerd images and containers
27 k3s crictl images
28 k3s crictl ps
29 # connect to container id
30 crictl exec -it 997a2ad8c763a sh
31 # connect to container/pod
32 kubectl get pods
33 kubectl exec -it springboot-test-6bb5fdfc48-phh8k sh
34 cat /etc/os-release # alpine linux in container
35 # give sudo rights to user
36 /sbin/usermod -aG sudo user
37 # scale pods
38 sudo kubectl scale deployment springboot-test --replicas=3
39 sudo kubectl get pods -o wide
40 # add mariadb pod/service
41 sudo kubectl create deployment mariadb-test --image=mariadb:latest
42 sudo kubectl get pods -o wide
43 sudo kubectl delete deployment mariadb-test
44 # https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/
45 sudo kubectl apply -f mariadb-pv.yaml
46 #persistentvolume/mariadb-pv-volume created
47 #persistentvolumeclaim/mariadb-pv-claim created
48 sudo kubectl apply -f mariadb-deployment.yaml
49 #service/mariadb created
50 #deployment.apps/mariadb created
51 sudo kubectl describe deployment mariadb
52 sudo kubectl get svc -o wide
53 # connect to mariabdb pod
54 sudo kubectl exec -it mariadb-8578f4dc8c-r4ftv /bin/bash
55 ss -atn # show ports tcp listening
56 ip address # show ip addresses
57 mysql -h localhost -p
58 mysql -u root -h 10.42.0.12 -p
59
60 # delete service, persistent volume claim and persistent volume
61 sudo kubectl delete deployment,svc mariadb
62 sudo kubectl delete pvc mariadb-pv-claim
63 sudo kubectl delete pv mariadb-pv-volume
mariadb-pv.yaml
1 apiVersion: v1
2 kind: PersistentVolume
3 metadata:
4 name: mariadb-pv-volume
5 labels:
6 type: local
7 spec:
8 storageClassName: manual
9 capacity:
10 storage: 1Gi
11 accessModes:
12 - ReadWriteOnce
13 hostPath:
14 path: "/mnt/data"
15 ---
16 apiVersion: v1
17 kind: PersistentVolumeClaim
18 metadata:
19 name: mariadb-pv-claim
20 spec:
21 storageClassName: manual
22 accessModes:
23 - ReadWriteOnce
24 resources:
25 requests:
26 storage: 1Gi
mariadb-deployment.yaml
1 apiVersion: v1
2 kind: Service
3 metadata:
4 name: mariadb
5 spec:
6 ports:
7 - port: 3306
8 selector:
9 app: mariadb
10 clusterIP: None
11 ---
12 apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
13 kind: Deployment
14 metadata:
15 name: mariadb
16 spec:
17 selector:
18 matchLabels:
19 app: mariadb
20 strategy:
21 type: Recreate
22 template:
23 metadata:
24 labels:
25 app: mariadb
26 spec:
27 containers:
28 - image: mariadb:latest
29 name: mariadb
30 env:
31 # Use secret in real usage
32 - name: MYSQL_ROOT_PASSWORD
33 value: password
34 ports:
35 - containerPort: 3306
36 name: mariadb
37 volumeMounts:
38 - name: mariadb-persistent-storage
39 mountPath: /var/lib/mariadb
40 volumes:
41 - name: mariadb-persistent-storage
42 persistentVolumeClaim:
43 claimName: mariadb-pv-claim
Init containers
Init containers can contain utilities or setup scripts not present in an app image.
systemctl commands
Ubuntu pod
ubuntu.yaml
Alpine pod
alpine.yaml
Nginx with persistent volume
pv-volume.yaml
pv-claim.yaml
pv-pod.yaml
1 apiVersion: v1
2 kind: Pod
3 metadata:
4 name: task-pv-pod
5 spec:
6 volumes:
7 - name: task-pv-storage
8 persistentVolumeClaim:
9 claimName: task-pv-claim
10 containers:
11 - name: task-pv-container
12 image: nginx
13 ports:
14 - containerPort: 80
15 name: "http-server"
16 volumeMounts:
17 - mountPath: "/usr/share/nginx/html"
18 name: task-pv-storage
1 sudo kubectl apply -f pv-volume.yaml
2 sudo kubectl apply -f pv-claim.yaml
3 sudo kubectl apply -f pv-pod.yaml
4 sudo kubectl get pods -o wide
5 curl http://10.42.0.28/
6 sudo kubectl exec -it task-pv-pod -- bash
7 cd /usr/share/nginx/html
8 echo "Hey from Kubernetes storage" > index.html
9 cat /etc/os-release # debian buster
10 kubectl delete pod task-pv-pod
11 kubectl delete pvc task-pv-claim
12 kubectl delete pv task-pv-volume
13 cat /tmp/data/index.html
Generate yaml
1 sudo kubectl create deployment cherrypy-test --image=vbodocker/cherrypy-test --dry-run=client --output=yaml
2 sudo kubectl expose deployment cherrypy-test --port=8080 --type=NodePort --dry-run=client --output=yaml
3 sudo kubectl scale deployment cherrypy-test --replicas=3 --dry-run=client --output=yaml
Alpine persistent volume
alpine-shared.yaml
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: alpine-pv-volume
labels:
type: local
spec:
storageClassName: manual
capacity:
storage: 0.2Gi
accessModes:
- ReadWriteOnce
hostPath:
path: "/tmp/alpine-data"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: alpine-pv-claim
spec:
storageClassName: manual
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 0.2Gi
---
apiVersion: v1
kind: Pod
metadata:
name: alpine-pod
labels:
app: alpine-pod
spec:
volumes:
- name: alpine-pv-storage
persistentVolumeClaim:
claimName: alpine-pv-claim
containers:
- name: alpine
image: alpine:latest
command: ["/bin/sleep", "3650d"]
imagePullPolicy: IfNotPresent
volumeMounts:
- mountPath: "/mnt/alpine/data"
name: alpine-pv-storage
restartPolicy: Always
MariaDB + NFS
1 /vol *(rw,sync,insecure,fsid=0,no_subtree_check,no_root_squash)
2 exportfs -rav
3 exporting *:/vol
4 mkdir -p /vol/mariadb-0
5
6 kubectl apply -f mariadb-nfs.yaml
7 kubectl exec -it mariadb-79847f5d97-smbdx -- bash
8 touch /var/lib/mariadb/b
9 mount | grep nfs
10 kubectl delete -f mariadb-nfs.yaml
11 kubectl get pods
12 kubectl get pvc
13 kubectl get pv
mariadb-nfs.yaml
1 ---
2 apiVersion: v1
3 kind: PersistentVolume
4 metadata:
5 name: mdb-vol-0
6 labels:
7 volume: mdb-volume
8 spec:
9 storageClassName: manual
10 capacity:
11 storage: 1Gi
12 accessModes:
13 - ReadWriteOnce
14 nfs:
15 server: 127.0.0.1
16 path: "/vol/mariadb-0"
17 ---
18 apiVersion: v1
19 kind: PersistentVolumeClaim
20 metadata:
21 name: mdb-pv-claim
22 spec:
23 storageClassName: manual
24 accessModes:
25 - ReadWriteOnce
26 resources:
27 requests:
28 storage: 1Gi
29 ---
30 apiVersion: v1
31 kind: Service
32 metadata:
33 name: mariadb
34 spec:
35 ports:
36 - port: 3306
37 selector:
38 app: mariadb
39 clusterIP: None
40 ---
41 apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
42 kind: Deployment
43 metadata:
44 name: mariadb
45 spec:
46 selector:
47 matchLabels:
48 app: mariadb
49 strategy:
50 type: Recreate
51 template:
52 metadata:
53 labels:
54 app: mariadb
55 spec:
56 containers:
57 - image: mariadb:latest
58 name: mariadb
59 env:
60 # Use secret in real usage
61 - name: MYSQL_ROOT_PASSWORD
62 value: password
63 ports:
64 - containerPort: 3306
65 name: mariadb
66 volumeMounts:
67 - name: mdb-persistent-storage
68 mountPath: /var/lib/mariadb
69 volumes:
70 - name: mdb-persistent-storage
71 persistentVolumeClaim:
72 claimName: mdb-pv-claim
Persistent volumes
A PersistentVolume (PV) is a piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes.
A PersistentVolumeClaim (PVC) is a request for storage by a user.
Pods consume node resources and PVCs consume PV resources. Claims can request specific size and access modes (e.g., they can be mounted ReadWriteOnce, ReadOnlyMany or ReadWriteMany, see AccessModes).
Types of Persistent Volumes:
- local - local storage devices mounted on nodes.
- nfs - Network File System (NFS) storage
Ingress controller nginx example
ingress-cherrypy-test.yml
Steps
1 # install k3s
2 curl -sfL https://get.k3s.io | sh -
3 KUBECONFIG=~/.kube/config
4 mkdir ~/.kube 2> /dev/null
5 sudo k3s kubectl config view --raw > "$KUBECONFIG"
6 chmod 600 "$KUBECONFIG"
7 nano ~/.bashrc
8 export KUBECONFIG=~/.kube/config
9 source . ~/.bashrc
10
11 sudo nano /etc/systemd/system/k3s.service
12 ExecStart=/usr/local/bin/k3s server --write-kubeconfig-mode=644
13 sudo systemctl daemon-reload
14 sudo service k3s start
15 sudo service k3s status
16 kubectl get pods
17
18 k3s kubectl cluster-info
19
20 kubectl -n kube-system delete helmcharts.helm.cattle.io traefik
21 sudo service k3s stop
22 sudo nano /etc/systemd/system/k3s.service
23 # ExecStart=/usr/local/bin/k3s server --write-kubeconfig-mode=644 --no-deploy traefik
24 sudo systemctl daemon-reload
25 sudo rm /var/lib/rancher/k3s/server/manifests/traefik.yaml
26 sudo service k3s start
27 kubectl -n kube-system delete helmcharts.helm.cattle.io traefik
28 sudo systemctl restart k3s
29
30 kubectl get nodes
31 kubectl delete node localhost
32 kubectl get pods --all-namespaces
33 kubectl get services --all-namespaces
34 kubectl get deployment --all-namespaces
35
36 # install nginx ingress controller
37 kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.4.0/deploy/static/provider/cloud/deploy.yaml
38 kubectl get pods --namespace=ingress-nginx
39
40 kubectl create deployment cherrypy-test --image=vbodocker/cherrypy-test
41 kubectl expose deployment cherrypy-test --port=8000 --target-port=8080 --type=ClusterIP # cluster ip port 8000
42 kubectl get services
43
44 kubectl apply -f ingress-cherrypy-test.yml
45
46 EXTERNAL_IP=$(ip addr show | grep wlp | grep inet | awk '//{print $2}' | sed 's/\// /g' | awk '//{print $1}')
47 echo $EXTERNAL_IP
48 sudo sh -c " echo '$EXTERNAL_IP cp.info' >> /etc/hosts "
49 kubectl get ingress
50 curl cp.info
51
52 kubectl scale deployment cherrypy-test --replicas=5
53 curl http://cp.info/ -vvv
54 sudo apt install apache2-utils
55 ab -n 10 -c 10 http://cp.info/
56
57 # Push image to docker hub
58 docker build -t vbodocker/cherrypy-test .
59 docker run -p 8080:8080 vbodocker/cherrypy-test
60 docker login # login to docker hub
61 docker push vbodocker/cherrypy-test
62 docker pull vbodocker/cherrypy-test:latest
63
64 # Rollout, deploy new image
65 kubectl get deployments -o wide # shows image urls
66 kubectl rollout restart deployment cherrypy-test # redeploy image url for cherrypy-test
67 kubectl rollout status deployment cherrypy-test
68 kubectl get deployments -o wide
69 kubectl get pods -o wide # age should be low for the newly deployed pods
70
Install k3s static binary in Slack64
Binaries available in https://github.com/k3s-io/k3s#manual-download
wget https://github.com/k3s-io/k3s/releases/download/v1.25.3%2Bk3s1/k3s
/etc/rc.d/rc.k3s
1 #!/bin/sh
2 PATH=$PATH:/usr/sbin
3
4 k3s_start() {
5 /usr/bin/k3s server --write-kubeconfig-mode=644 \
6 --disable traefik > /var/log/k3s.log 2>&1 &
7 }
8
9 k3s_stop() {
10 kill $(ps uax | grep "/usr/bin/k3s" | head -1 | awk '//{print $2}')
11 ps uax | grep containerd | awk '//{print $2}' | xargs -i kill {}
12 }
13
14 k3s_restart() {
15 k3s_stop
16 k3s_start
17 }
18
19 case "$1" in
20 'start')
21 k3s_start
22 ;;
23 'stop')
24 k3s_stop
25 ;;
26 'restart')
27 k3s_restart
28 ;;
29 *)
30 echo "usage $0 start|stop|restart"
31 esac
ingress-cherrypy-test.yml
Steps
1 echo "alias kubectl='/usr/bin/k3s kubectl'" >> ~/.bashrc
2 source ~/.bashrc
3 sudo sh /etc/rc.d/rc.k3s start
4 kubectl get nodes
5 kubectl get deployments --all-namespaces
6 kubectl get services --all-namespaces
7 kubectl get pods --all-namespaces
8 kubectl cluster-info
9 # install nginx ingress controller
10 kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.4.0/deploy/static/provider/cloud/deploy.yaml
11 # wait for nginx ingress controller to finish
12 sleep 120
13 kubectl create deployment cherrypy-test --image=vbodocker/cherrypy-test
14 kubectl expose deployment cherrypy-test --port=8000 --target-port=8080 --type=ClusterIP
15 kubectl get pods --all-namespaces
16 kubectl get services --all-namespaces
17 kubectl apply -f ingress-cherrypy-test.yml
18 EXTERNAL_IP=$(/sbin/ip addr show | grep wl | grep inet | awk '//{print $2}' | sed 's/\// /g' | awk '//{print $1}')
19 echo $EXTERNAL_IP
20 sudo sh -c " echo '$EXTERNAL_IP cp.info' >> /etc/hosts "
21 cat /etc/hosts
22 kubectl get ingress
23 curl cp.info