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Kubernetes

Sumario

Primeiros passos com Kubernetes

Listando nossos nodes com kubectl get nodes:

  1. Iniciando a aula e vendo que nosso cluster esta funcionando legal:
# kubectl get nodes
NAME                    STATUS   ROLES                  AGE    VERSION
kube-worker01           Ready    <none>                 9h     v1.23.1
kube-worker2            Ready    <none>                 114s   v1.23.1
localhost.localdomain   Ready    control-plane,master   10h    v1.23.1

Antes de prosseguir alguns conceitos...

  • no Kubernetes temos nodes worker e nodes master.
  • no master vai ter o APIserver, gerencia do meu cluster.
    • se os nodes etstao saudaveis, se ele esta comunicando com o master.
  • por default o master nao recebe containers, somente nos workers.

Usando o comando kubectl describe para mais detalhes

  1. Vamos agora testar o comando kubectl describe para ver os detalhes do master:
# kubectl describe nodes k8smaster
Name:               k8smaster
Roles:              control-plane,master
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=k8smaster
                    kubernetes.io/os=linux
                    node-role.kubernetes.io/control-plane=
                    node-role.kubernetes.io/master=
                    node.kubernetes.io/exclude-from-external-load-balancers=
Annotations:        kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
                    node.alpha.kubernetes.io/ttl: 0
                    volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp:  Sun, 27 Feb 2022 12:32:58 -0300
Taints:             node-role.kubernetes.io/master:NoSchedule
Unschedulable:      false
Lease:
  HolderIdentity:  k8smaster
  AcquireTime:     <unset>
  RenewTime:       Sat, 05 Mar 2022 14:02:00 -0300
Conditions:
  Type                 Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
  ----                 ------  -----------------                 ------------------                ------                       -------
  NetworkUnavailable   False   Wed, 02 Mar 2022 15:19:09 -0300   Wed, 02 Mar 2022 15:19:09 -0300   WeaveIsUp                    Weave pod has set this
  MemoryPressure       False   Sat, 05 Mar 2022 13:57:52 -0300   Sun, 27 Feb 2022 12:32:54 -0300   KubeletHasSufficientMemory   kubelet has sufficient memory available
  DiskPressure         False   Sat, 05 Mar 2022 13:57:52 -0300   Sun, 27 Feb 2022 12:32:54 -0300   KubeletHasNoDiskPressure     kubelet has no disk pressure
  PIDPressure          False   Sat, 05 Mar 2022 13:57:52 -0300   Sun, 27 Feb 2022 12:32:54 -0300   KubeletHasSufficientPID      kubelet has sufficient PID available
  Ready                True    Sat, 05 Mar 2022 13:57:52 -0300   Sun, 27 Feb 2022 12:40:03 -0300   KubeletReady                 kubelet is posting ready status
Addresses:

Adicionando novcs nodes ao cluster

  1. Agora vamos executar um comando para adicionar novos nodes ao cluster:
# kubeadm token create --print-join-command
kubeadm join 192.168.1.114:6434 --token j7ivmo.up6haifmk55pou7c --discovery-token-ca-cert-hash sha256:3fc69efd6451dedb945ce665bdf436ac3e54e0e55774fb0654b60562677944f7

Ativando o auto-complete para sistemas Red Hat

  1. Para ativar o auto-complete Red Hat based:
$ yum install bash-completion -y ; kubectl completion bash > /etc/bash_completion.d/kubectl
  1. Para ativar o auto-complete execute:
$ source <(kubectl completion bash)

Buscando os POD's do namespace kube-systems

  1. Vamos agora descrever um POD:
# kubectl get pods -n kube-system
NAME                                READY   STATUS    RESTARTS       AGE
coredns-64897985d-dkmwn             1/1     Running   1 (3d1h ago)   6d4h
coredns-64897985d-sj8s8             1/1     Running   1 (3d1h ago)   6d4h
etcd-k8smaster                      1/1     Running   1 (3d1h ago)   6d4h
kube-apiserver-k8smaster            1/1     Running   1 (3d1h ago)   6d4h
kube-controller-manager-k8smaster   1/1     Running   1 (3d1h ago)   6d4h
kube-proxy-5c7lt                    1/1     Running   1 (3d1h ago)   6d3h
kube-proxy-7cmng                    1/1     Running   1 (3d1h ago)   6d4h
kube-proxy-clgln                    1/1     Running   1 (3d1h ago)   6d3h
kube-scheduler-k8smaster            1/1     Running   1 (3d1h ago)   6d4h
weave-net-bkc5w                     2/2     Running   3 (3d1h ago)   6d4h
weave-net-cqvn8                     2/2     Running   2 (3d1h ago)   6d3h
weave-net-tfskb                     2/2     Running   2 (3d1h ago)   6d3h

Entendendo que um POD tambem tem mais de um container

  • um POD por ter mais de um container veja o caso acima do weave-net-bkc5w.
    • esses containers compartlha o mesmo IP, nome, mesmo namespace.
    • namespace: funciona como um cercado, voce tem maior controle da sua app.

Aqui agora descrevendo os POD's do Kube-System:

# kubectl describe pods -n kube-system
Name:                 coredns-64897985d-7wkj2
Namespace:            kube-system
Priority:             2000000000
Priority Class Name:  system-cluster-critical
Node:                 localhost.localdomain/192.168.0.155
Start Time:           Sat, 15 Jan 2022 16:21:31 -0300
Labels:               k8s-app=kube-dns
                      pod-template-hash=64897985d
Annotations:          <none>
Status:               Running
IP:                   10.32.0.2
IPs:
  IP:           10.32.0.2
Controlled By:  ReplicaSet/coredns-64897985d
Containers:
  coredns:
    Container ID:  docker://921353442b349cc1e77c7cc150701486b9782c6682324aae1cea7b1100062544
    Image:         k8s.gcr.io/coredns/coredns:v1.8.6
    Image ID:      docker-pullable://k8s.gcr.io/coredns/coredns@sha256:5b6ec0d6de9baaf3e92d0f66cd96a25b9edbce8716f5f15dcd1a616b3abd590e
    Ports:         53/UDP, 53/TCP, 9153/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      -conf
      /etc/coredns/Corefile
    State:          Running
      Started:      Mon, 17 Jan 2022 10:53:19 -0300
    Last State:     Terminated
      Reason:       Error
      Exit Code:    255
      Started:      Sat, 15 Jan 2022 16:49:02 -0300
      Finished:     Mon, 17 Jan 2022 10:52:03 -0300
    Ready:          True
    Restart Count:  1
  • eu posso ter mais de 1 container dentro de um mesmo POD.
  • esses containers compartilham o mesmo IP entre eles.

Mais detalhes do POD weave-net-cqvn8:

# kubectl describe pods -n kube-system weave-net-cqvn8
Name:                 weave-net-cqvn8
Namespace:            kube-system
Priority:             2000001000
Priority Class Name:  system-node-critical
Node:                 k8snode01/192.168.0.220
Start Time:           Sun, 27 Feb 2022 14:49:49 -0300
Labels:               controller-revision-hash=59d968cb54
                      name=weave-net
                      pod-template-generation=1
Annotations:          <none>
Status:               Running
IP:                   192.168.0.220
IPs:
  IP:           192.168.0.220
Controlled By:  DaemonSet/weave-net
Init Containers:
  weave-init:
    Container ID:  docker://01cfc8b8e6e4041c75ce9f7ad43426705ab4bd053f354f96f824eedf7aee5c93
    Image:         ghcr.io/weaveworks/launcher/weave-kube:2.8.1
    Image ID:      docker-pullable://ghcr.io/weaveworks/launcher/weave-kube@sha256:d797338e7beb17222e10757b71400d8471bdbd9be13b5da38ce2ebf597fb4e63
    Port:          <none>
    Host Port:     <none>
    Command:
      /home/weave/init.sh
    State:          Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Wed, 02 Mar 2022 15:19:14 -0300
      Finished:     Wed, 02 Mar 2022 15:19:17 -0300
    Ready:          True
    Restart Count:  1
    Environment:    <none>
    Mounts:
      /host/etc from cni-conf (rw)
      /host/home from cni-bin2 (rw)
      /host/opt from cni-bin (rw)
      /lib/modules from lib-modules (rw)
      /run/xtables.lock from xtables-lock (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-bs7dw (ro)
Containers:
  weave:
    Container ID:  docker://d591211f201a4412a76670a158d64b5ee1807ee47e9bb011ef0aa3a99550e86e
    Image:         ghcr.io/weaveworks/launcher/weave-kube:2.8.1
    Image ID:      docker-pullable://ghcr.io/weaveworks/launcher/weave-kube@sha256:d797338e7beb17222e10757b71400d8471bdbd9be13b5da38ce2ebf597fb4e63
    Port:          <none>
    Host Port:     <none>
    Command:
      /home/weave/launch.sh

Visualizando os namespaces

  1. Para visualizar todos os namespaces dos meus PODS ativos:
]# kubectl get pods --all-namespaces
NAMESPACE     NAME                                READY   STATUS    RESTARTS       AGE
kube-system   coredns-64897985d-dkmwn             1/1     Running   1 (3d1h ago)   6d4h
kube-system   coredns-64897985d-sj8s8             1/1     Running   1 (3d1h ago)   6d4h
kube-system   etcd-k8smaster                      1/1     Running   1 (3d1h ago)   6d4h
kube-system   kube-apiserver-k8smaster            1/1     Running   1 (3d1h ago)   6d4h
kube-system   kube-controller-manager-k8smaster   1/1     Running   1 (3d1h ago)   6d4h
kube-system   kube-proxy-5c7lt                    1/1     Running   1 (3d1h ago)   6d3h
kube-system   kube-proxy-7cmng                    1/1     Running   1 (3d1h ago)   6d4h
kube-system   kube-proxy-clgln                    1/1     Running   1 (3d1h ago)   6d4h
kube-system   kube-scheduler-k8smaster            1/1     Running   1 (3d1h ago)   6d4h
kube-system   weave-net-bkc5w                     2/2     Running   3 (3d1h ago)   6d4h
kube-system   weave-net-cqvn8                     2/2     Running   2 (3d1h ago)   6d4h
kube-system   weave-net-tfskb                     2/2     Running   2 (3d1h ago)   6d3h

Visualizando namespaces dos POD's ativos

  • Para visualizar todos os namespaces dos meus PODS ativos:
# kubectl get pods --all-namespaces -o wide
NAMESPACE     NAME                                READY   STATUS    RESTARTS       AGE    IP              NODE        NOMINATED NODE   READINESS GATES
kube-system   coredns-64897985d-dkmwn             1/1     Running   1 (3d1h ago)   6d4h   10.32.0.3       k8smaster   <none>           <none>
kube-system   coredns-64897985d-sj8s8             1/1     Running   1 (3d1h ago)   6d4h   10.32.0.2       k8smaster   <none>           <none>
kube-system   etcd-k8smaster                      1/1     Running   1 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   kube-apiserver-k8smaster            1/1     Running   1 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   kube-controller-manager-k8smaster   1/1     Running   1 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   kube-proxy-5c7lt                    1/1     Running   1 (3d1h ago)   6d3h   192.168.0.136   k8snode02   <none>           <none>
kube-system   kube-proxy-7cmng                    1/1     Running   1 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   kube-proxy-clgln                    1/1     Running   1 (3d1h ago)   6d4h   192.168.0.217   k8snode01   <none>           <none>
kube-system   kube-scheduler-k8smaster            1/1     Running   1 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   weave-net-bkc5w                     2/2     Running   3 (3d1h ago)   6d4h   192.168.0.235   k8smaster   <none>           <none>
kube-system   weave-net-cqvn8                     2/2     Running   2 (3d1h ago)   6d4h   192.168.0.215   k8snode01   <none>           <none>
kube-system   weave-net-tfskb                     2/2     Running   2 (3d1h ago)   6d3h   192.168.0.135   k8snode02   <none>           <none>
  1. Para visualizar todos os namespaces que eu tenho criado no meu control-plane, cluster:
# kubectl get namespaces
NAME              STATUS   AGE
default           Active   44h
kube-node-lease   Active   44h
kube-public       Active   44h
kube-system       Active   44h

Criando um namespace

  • esses namespaces sao padroes do Kubernetes.

8.1. Vamos agora criar um novo namespace, para isso devemos executar o comando abaixo:

# kubectl create namespace devops
namespace/devops created
  • Agora tenho ele listado:
# kubectl get namespaces
NAME              STATUS   AGE
amarops           Active   118s
default           Active   44h
kube-node-lease   Active   44h
kube-public       Active   44h
kube-system       Active   44h

Criando um novo POD com kubectl run

  1. Criando agora um novo POD (quando ele executa o comando run ele cria um POD):
# kubectl run nginx --image=nginx
pod/nginx created

9.1 Listando meu POD criado:

# kubectl get pods
NAME    READY   STATUS    RESTARTS      AGE
nginx   1/1     Running   1 (98m ago)   35h

Analisando o POD criado

9.2 Vendo mais detalhes desse POD:

# kubectl get pods nginx  -o wide
NAME    READY   STATUS    RESTARTS   AGE    IP          NODE        NOMINATED NODE   READINESS GATES
nginx   1/1     Running   0          100s   10.44.0.2   k8snode01   <none>           <none>

9.3 Mais detalhes do POD:

# kubectl describe pods nginx
Name:         nginx
Namespace:    default
Priority:     0
Node:         kube-worker01/192.168.1.210
Start Time:   Sun, 16 Jan 2022 00:48:48 -0300
Labels:       run=nginx
Annotations:  <none>
Status:       Running
IP:           10.44.0.1
IPs:
  IP:  10.44.0.1
Containers:
  nginx:
    Container ID:   docker://223d5b1e749a2065a760dd4cc8e71826504e5832b6632d67753f9e23c3673d52
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:0d17b565c37bcbd895e9d92315a05c1c3c9a29f762b011a10c54a66cd53c9b31
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Mon, 17 Jan 2022 10:53:03 -0300
    Last State:     Terminated
      Reason:       Error
      Exit Code:    255
      Started:      Sun, 16 Jan 2022 00:49:14 -0300
      Finished:     Mon, 17 Jan 2022 10:52:10 -0300
    Ready:          True
    Restart Count:  1
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-bx8dc (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  kube-api-access-bx8dc:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:                      <none>

Manifestos do Kubernetes: Use sempre o YML para acessar os manifestos

  1. Agora quero visualizar mais detalhes do POD do nginx, buscando o manifesto (objeto YML) no formato yml:
  • esse POD vem com mais sujeiras do k8s (podemos remover algumas linhas).
# kubectl get pods nginx -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2022-03-05T20:22:00Z"
  labels:
    run: nginx
  name: nginx
  namespace: default
  resourceVersion: "372146"
  uid: 4f255e36-4725-4e0e-82f1-4f34235d8e5d
spec:
  containers:
  - image: nginx
    imagePullPolicy: Always
    name: nginx
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-mfq45
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: k8snode01
  preemptionPolicy: PreemptLowerPriority
  priority: 0
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  serviceAccount: default
  serviceAccountName: default
  terminationGracePeriodSeconds: 30
  tolerations:
  - effect: NoExecute
    key: node.kubernetes.io/not-ready
    operator: Exists
    tolerationSeconds: 300
  - effect: NoExecute
    key: node.kubernetes.io/unreachable
    operator: Exists
    tolerationSeconds: 300
  volumes:
  - name: kube-api-access-mfq45
    projected:
      defaultMode: 420
      sources:
      - serviceAccountToken:
          expirationSeconds: 3607
          path: token
      - configMap:
          items:
          - key: ca.crt
            path: ca.crt
          name: kube-root-ca.crt
      - downwardAPI:
          items:
          - fieldRef:
              apiVersion: v1
              fieldPath: metadata.namespace
            path: namespace
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2022-03-05T06:39:08Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2022-03-05T06:39:13Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2022-03-05T06:39:13Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2022-03-05T20:22:00Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: docker://87a580be57bb0ea333fe860eb1ef480a70acede42cf3b1e8a0065fcc2582aee2
    image: nginx:latest
    imageID: docker-pullable://nginx@sha256:859ab6768a6f26a79bc42b231664111317d095a4f04e4b6fe79ce37b3d199097
    lastState: {}
    name: nginx
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2022-03-05T06:39:12Z"
  hostIP: 192.168.0.220
  phase: Running
  podIP: 10.44.0.2
  podIPs:
  - ip: 10.44.0.2
  qosClass: BestEffort
  startTime: "2022-03-05T06:39:08Z"
  • como ele foi criado para o Kubernetes
  • quando eu quiser criar um POD atraves do yml preciso fazer algo assim
  • muita coisa e lixo eu nao preciso

10.1. Primeiro vamos redirecionar um POD de teste para que eu tenha um exemplo:

# kubectl get pods nginx -o yaml >> meu_primeiro_pod_nginx.yml

O YML mais enxuto depois de analisado

10.2. Nosso yml file modificado:

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: nginx
  name: nginx
  namespace: amarops
spec:
  containers:
  - image: nginx
    imagePullPolicy: Always
    name: nginx
  dnsPolicy: ClusterFirst
  restartPolicy: Always

Criando nosso POD com kubectl apply

10.3. Agora sim vamos criar nosso primeiro POD e usar ele no meu namesoace devops:

# kubectl apply -f primeiro_pod_nginx.yml
pod/nginx created

10.3.a. Eu tambem posso remover/deletar esse POD:

# kubectl delete -f primeiro_pod_nginx.yml
pod "nginx" deleted

Simulando a criacao do POD

10.3.b. Tambem posso simular uma criacao de POD ja com o YML:

# kubectl run nginx --image=nginx --dry-run=client
pod/nginx created (dry run)

10.3.c. Ele vem com o YMLenxuto:

# kubectl run nginx --image=nginx --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
  • Posso dar apply:
# kubectl apply -f segundo_pod_nginx.yml
pod/nginx created

10.4. Se eu listar agora meu namespace eu posso ver meu POD:

# kubectl get pods -n devops
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          2m21s

10.5. Veja que eu posso tambem aproveitar um comando que ja me fornece o yml exatamente como eu preciso:

  • a opcao dry-run apenas simula a criacao do POD
# kubectl run nginx --image=nginx --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
  • veja agora:
# kubectl get pods
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          16s

Services

  1. Primeiramente vamos comecar analisando nosso POD:
# kubectl get pods
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          4h45m

Criando o primeiro service

  1. Agora vamos usar um outro comando para criar nosso service:
# kubectl expose pod nginx
error: couldn't find port via --port flag or introspection
See 'kubectl expose -h' for help and examples

Usando o comando expose

  • veja que ele retornou um erro pedindo para setar a porta.
  • vamos usar o YML para subir com a porta.
  • ClusterIP serve apenas executar dentro do cluster.
  • NodePort serve para ser acessado de fora do cluster (ele tras uma porta de 30000 ate 32500)
  1. Agora que editei a porta no YML file vamos executar de novo o comando expose:
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
    ports:
    - containerPort: 80
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
  1. Veja que agora podemos expor o service:
# kubectl expose pod nginx
service/nginx exposed
  1. Listando:
# kubectl describe pods nginx | grep -i port
    Port:           80/TCP
    Host Port:      0/TCP
  1. Veja que ele agora possui um service criado:
# kubectl get service
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP   6d10h
nginx        ClusterIP   10.106.174.205   <none>        80/TCP    14s
  1. Testando usando o comando curl:
# curl 10.106.174.205
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

Detalhes do service

  1. Veja agora mais detalhes do service:
# kubectl describe service nginx
Name:              nginx
Namespace:         default
Labels:            run=nginx
Annotations:       <none>
Selector:          run=nginx
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                10.106.174.205
IPs:               10.106.174.205
Port:              <unset>  80/TCP
TargetPort:        80/TCP
Endpoints:         10.44.0.1:80
Session Affinity:  None
Events:            <none>

Como editar um service usando o comando kubectl edit

  1. Vamos editar nosso service do NGINX:
# kubectl edit service nginx
service/nginx edited
  • mudei de ClusterIP -> NodePort
  • veja que agora ele aparece com a porta
# kubectl get service
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP        6d10h
nginx        NodePort    10.106.174.205   <none>        80:30654/TCP   11m
  1. Vou acessar no browser o IP da minha instancia com essa porta:

http://192.168.0.222:30654/

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and working. Further configuration is required.

For online documentation and support please refer to nginx.org.
Commercial support is available at nginx.com.

Thank you for using nginx.

Analisando o YML do meu service

  1. Pegando o YML do meu service:

# kubectl get service nginx -o yaml

apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2022-03-06T01:49:05Z"
  labels:
    run: nginx
  name: nginx
  namespace: default
  resourceVersion: "400096"
  uid: 040663fa-43be-4335-8517-95f70e9459e0
spec:
  clusterIP: 10.106.174.205
  clusterIPs:
  - 10.106.174.205
  externalTrafficPolicy: Cluster
  internalTrafficPolicy: Cluster
  ipFamilies:
  - IPv4
  ipFamilyPolicy: SingleStack
  ports:
  - nodePort: 30654
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    run: nginx
  sessionAffinity: None
  type: NodePort
status:
  loadBalancer: {}

Explicando os comandos do Kubernetes

  1. Podemos tambem usar um comando que mostra detalhes de cada componente do k8s:
# kubectl explain pods
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

FIELDS:
   apiVersion   <string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind <string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata     <Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   spec <Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

   status       <Object>
     Most recently observed status of the pod. This data may not be up to date.
     Populated by the system. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

# kubectl explain svc

KIND:     Service
VERSION:  v1

DESCRIPTION:
     Service is a named abstraction of software service (for example, mysql)   
     consisting of local port (for example 3306) that the proxy listens on, and
     the selector that determines which pods will answer requests sent through 
     the proxy.

FIELDS:
   apiVersion   <string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind <string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata     <Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   spec <Object>
     Spec defines the behavior of a service.
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

   status       <Object>
     Most recently observed status of the service. Populated by the system.
     Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

Encadeamento de Comandos

  1. Tambem podemos executar muitos comandos ao mesmo tempo:
# kubectl get pods,services,endpoints
NAME        READY   STATUS    RESTARTS   AGE
pod/nginx   1/1     Running   0          113m

NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP        6d12h
service/nginx        NodePort    10.106.174.205   <none>        80:30654/TCP   112m

NAME                   ENDPOINTS            AGE
endpoints/kubernetes   192.168.0.234:6443   6d12h
endpoints/nginx        10.44.0.1:80         112m

Comandos do Kubernetes abreviados

  1. Podemos usar abreviacoes de comandos:
# kubectl get po
No resources found in default namespace.

tambem:

# kubectl get ns
NAME              STATUS   AGE
default           Active   6d12h
devops            Active   7h23m
kube-node-lease   Active   6d12h
kube-public       Active   6d12h
kube-system       Active   6d12h

tambem:

# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   6d12h