Differences between revisions 10 and 11

k8s/StudyNotes

k8s/StudyNotes/cubectl k8s/StudyNotes/Deployments k8s/StudyNotes/Pods k8s/StudyNotes/Services

Links
- https://kodekloud.com/
- Certified Kubernetes Administrator: https://www.cncf.io/certification/cka/
- Exam Curriculum (Topics): https://github.com/cncf/curriculum
- Candidate Handbook: https://www.cncf.io/certification/candidate-handbook
- Exam Tips: http://training.linuxfoundation.org/go//Important-Tips-CKA-CKAD
- Use the code – DEVOPS15 – while registering for the CKA or CKAD exams at Linux Foundation to get a 15% discount.
kubeadm
- deploys all the kubernetes services downloaded from web
Kube-Scheduler
1. Filter Nodes (Pod cant fit)
2. Rank Nodes (Compare resources left, try to balance cpu/mem usage)
kubelet - captain on each Worker Node
- Registers with Master node, reports status and executes
- Always manual install wget https://storage.googleapis.com/kubernetes-release/release/v1.xx.x/bin/linux/amd64/kubelet
  - Not kubeadm managed.
  - Needs tls bootstrap
Kube-proxy - run on each node, service's virtual component
- All pods can see all other pods, through POD Network, by IP/Name. Exposed through service: eg. db(IP)
- Watches for service creation, and then configure network e.g. Iptables to forward to actual pod.
- Install: download wget to install or
  - kubeadm will deploy it as deamon set to each pod in namespace kube-system
kind: Deployments - Encapsulates ReplicaSet that Encapsulate Pods
- Can have deployment and replacement policy
kind: ResourceQuote
- spec:
  - hard:
    - cpu:

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  Editor: PieterSmit
  Comment:
+   ← Revision 11 as of 2021-10-19 18:46:58 → ⇥
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  Editor: PieterSmit
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 7:
- * https://kodekloud.com/
Certified Kubernetes Administrator: https://www.cncf.io/certification/cka/

Exam Curriculum (Topics): https://github.com/cncf/curriculum

Candidate Handbook: https://www.cncf.io/certification/candidate-handbook

Exam Tips: http://training.linuxfoundation.org/go//Important-Tips-CKA-CKAD

Use the code – DEVOPS15 – while registering for the CKA or CKAD exams at Linux Foundation to get a 15% discount.
+ * Links
   * https://kodekloud.com/
   * Certified Kubernetes Administrator: https://www.cncf.io/certification/cka/
   * Exam Curriculum (Topics): https://github.com/cncf/curriculum
   * Candidate Handbook: https://www.cncf.io/certification/candidate-handbook
   * Exam Tips: http://training.linuxfoundation.org/go//Important-Tips-CKA-CKAD
   * Use the code – DEVOPS15 – while registering for the CKA or CKAD exams at Linux Foundation to get a 15% discount.
-Line 37:
+Line 34:
- * PODs
   * smallest object in k8s, contains containers, can contain one or more containers
   * scale service by creating more pod instances.
   * additional container could be helper container. 
   * network space is shared between containers in the same pod, they can communicate on localhost.

  * k8s Controllers - the brains
    * kind: !ReplicaSets - Replication controller -> newer -> Replica Sets
      1. yml definition ```ReplicationController```  same 4 sections as other configs
        * apiVersion: v1
        * kind: !ReplicationController
        * metadata:
            name: myapp-rc
            labels:
              app: myapp
              type: front-end
        * spec:
            template:
              <pod definition nested, with same 2 sections, metadata, spec>
            replicas: 3

      1. yml definition newer ```ReplicationSet```, requires selector: {{{
         apiVersion: apps/v1
         kind: ReplicaSet
         metadata:
           name: myapp-rc
           labels:
             app: myapp
             type: front-end
           selector:
             app: myapp
             type: front-end
          }}}
        * spec:
            template:
              <pod definition nested, with same 2 sections, metadata, spec>
            replicas: 3
            selector:
                matchLabels:
                  type: front-end
-Line 88:
+Line 45:
- * kind: Service , 
    1. Service-!NodePort k8s-Obj-bind external node port to internal. NodePort is external port 30000-32767  {{{   
         apiVersion: v1
         kind: Service
         metadata:
           name: myapp-service
         spec:
           type: NodePort
           ports:
            - targetPort: 80   ->POD
              port: 80         ->This service local ip port (Optional)
              nodePort: 30008  ->Node external port listening on host, same port on all Nodes!
           selector:
             app: myapp
             type: front-end
       }}}
    2. Service-!ClusterIP internal network, default type {{{
         apiVersion: v1
         kind: Service
         metadata:
           name: back-end-service
         spec:
           type: ClusterIP   << Default if not specified
           ports:
            - targetPort: 80
              port: 80
           selector:
             name: my-app
             type: back-end     
       }}}
    3. Service-!LoadBalancer - Configure external LB {{{
         apiVersion: v1
         kind: Service
         metadata:
           name: myapp-service
         spec:
           type: Loadbalancer
           ports:
            - targetPort: 80
              port: 80
              nodePort: 30008
           selector:
             name: my-app
             type: back-end        
       }}}