(CKA) 07. Storage

CKA를 준비하면서 공부한 요약 내용입니다.

Docker Storage

File system

Layered architecture

build
- application 1
- application 2
run
copy-on-write

Volumes

Volume mounting

create and run
- create
  - docker volume create data_volume
- run
  - docker run -v data_volume:/var/lib/mysql mysql
create by run
- docker run -v data_volume2:/var/lib/mysql mysql
- automatically create data_volume

Bind mounting

docker run -v /data/mysql:/var/lib/mysql mysql

Preferred

old
- -v
new
- --mount
- docker run --mount type=bind,source=/data/mysql,target=/var/lib/mysql mysql

Storage drivers

AUFS
ZFS
BTFS
Device Mapper
Overlay
Overlay2

Volume Drivers

Local
Azure File Storage
Convoy
…

Volumes

docker
k8s

Volumes & Mounts

definition

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apiVersion: v1
kind: Pod
metadat:
  name: random-number-generator
spec:
  containers:
  - image: alpine
    name: alpine
    command: ["bin/sh", "-c"]
    args: ["shuf -i 0-100 -n 1 >> /opt/number.out;"]
    volumeMounts:
    - mountPath: /opt
      name: data-volume
  volumes:
  - name: data-volume
    hostPath:
      path: /data
      type: Directory

hostPath
- → single node is possible
- → not recommended in multi node

AWS

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  volumes:
  - name: data-volume
    awsElastricBlockStore:
      volumeID: <volume-id>
      fsType: ext4

Persistent Volume

생성

definition

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apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-vol1
spec:
  persistentVolumeReclaimPolicy: Retain
  accessModes:
    - ReadWriteOnce
  capacity:
    storage: 1Gi
  hostPath:
    path: /tmp/data

accessModes
- ReadOnlyMany
- ReadWriteOnce
- ReadWriteMany
persistentVolumeReclaimPolicy
- delete
- recycle
- retain

상태

kubectl get persistentvolume
kubectl get pv

Persistent Volume Claims

Persistent Volume
- administrator crates
Persistent Volume Claims
- users create to use persistent volume

생성

definition

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apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi

상태

kubectl get persistentvolumeclaim
kubectl get pvc

삭제

kubectl delete persistentvolumne myclaim

Pod with PVC

생성

definition w\ hostPath

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apiVersion: v1
kind: Pod
metadata:
  name: webapp
spec:
  containers:
  - name: event-simulator
    image: kodekloud/event-simulator
    env:
    - name: LOG_HANDLERS
      value: file
    volumeMounts:
    - mountPath: /log
      name: log-volume
  volumes:
  - name: log-volume
    hostPath:
      ## directory location on host
      path: /var/log/webapp
      ## this field is optional
      type: Directory

definition w\ PVC

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apiVersion: v1
kind: Pod
metadata:
  name: webapp
spec:
  containers:
  - name: event-simulator
    image: kodekloud/event-simulator
    env:
    - name: LOG_HANDLERS
      value: file
    volumeMounts:
    - mountPath: /log
      name: log-volume

  volumes:
  - name: log-volume
    persistentVolumeClaim:
      claimName: claim-log-1

Storage Class

상태

kubectl get storageclass
kubectl get sc