k8s之使用secret獲取私有倉庫鏡像

一、前言

其實這次實踐算不上特別復雜，只是在實踐過程中遇到了一些坑，以及填坑的方法是非常值得在以后的學習過程中參考借鑒的

二、知識准備

1.harbor是一個企業級的鏡像倉庫，它比起docker registry提供了更多的功能
2.在私有倉庫中的鏡像是需要經過一系列的驗證才能夠被pull，比如insecure-registries等
3.本文主要描述通過k8s的secret來進行驗證

三、環境准備

組件	版本
OS	Ubuntu 18.04.1 LTS
docker	18.06.0-ce
k8s	1.10.1
harbor	v1.5.3

四、創建secret

根據官方文檔 https://v1-10.docs.kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/

root@k8s-master:~# kubectl create secret docker-registry regcred \
>         --docker-server=repo.mrvolleyball.com/library \
>         --docker-username=admin \
>         --docker-password='Harbor12345' \
>         --docker-email=[e-mail]
secret "regcred" created

root@k8s-master:~# kubectl apply -f <(echo 'apiVersion: v1
> kind: Pod
> metadata:
>   name: private-reg
> spec:
>   containers:
>   - name: private-reg-container
>     image: repo.mrvolleyball.com/library/busybox:latest
>   imagePullSecrets:
>   - name: regcred')
pod "private-reg" created

根本沒有難度啊，2條命令解決，當我滿懷欣喜的查看狀態的時候：

root@k8s-master:~# kubectl get pods private-reg
NAME          READY     STATUS             RESTARTS   AGE
private-reg   0/1       ImagePullBackOff   0          11s

root@k8s-master:~# kubectl describe pods private-reg
...
Events:
  Type     Reason                 Age                From                 Message
  ----     ------                 ----               ----                 -------
  Normal   Scheduled              40s                default-scheduler    Successfully assigned private-reg to k8s-master
  Normal   SuccessfulMountVolume  40s                kubelet, k8s-master  MountVolume.SetUp succeeded for volume "default-token-v9nkm"
  Normal   SandboxChanged         38s                kubelet, k8s-master  Pod sandbox changed, it will be killed and re-created.
  Normal   Pulling                22s (x2 over 39s)  kubelet, k8s-master  pulling image "repo.mrvolleyball.com/library/busybox:latest"
  Warning  Failed                 22s (x2 over 38s)  kubelet, k8s-master  Failed to pull image "repo.mrvolleyball.com/library/busybox:latest": rpc error: code = Unknown desc = Error response from daemon: pull access denied for repo.mrvolleyball.com/library/busybox, repository does not exist or may require 'docker login'
  Warning  Failed                 22s (x2 over 38s)  kubelet, k8s-master  Error: ErrImagePull
  Normal   BackOff                6s (x4 over 36s)   kubelet, k8s-master  Back-off pulling image "repo.mrvolleyball.com/library/busybox:latest"
  Warning  Failed                 6s (x4 over 36s)   kubelet, k8s-master  Error: ImagePullBackOff

這簡直是給了當頭一棒啊，我反反復復的檢查之后，用戶名、密碼、倉庫地址，官網提供的命令，都沒問題啊，這TM到底是幾個意思！！

在我一遍又一遍的check中發現了蛛絲馬跡

root@k8s-master:~# kubectl get secret regcred  -o yaml
apiVersion: v1
data:
  .dockercfg: eyJhdXRocyI6eyJqZC1yZXBvLmludC5hbmtlcmppZWRpYW4uY29tIjp7InVzZXJuYW1lIjoiYWRtaW4iLCJwYXNzd29yZCI6IkhhcmJvcjEyMzQ1IiwiZW1haWwiOiJ5dXhpYW9jQGp1bWVpLmNvbSIsImF1dGgiOiJZV1J0YVc0NlNHRnlZbTl5TVRJek5EVT0ifX19
kind: Secret
metadata:
  creationTimestamp: 2018-10-29T09:33:40Z
  name: regcred
  namespace: default
  resourceVersion: "7670942"
  selfLink: /api/v1/namespaces/default/secrets/regcred
  uid: b82b7527-db5d-11e8-9e67-b2aca3e7fa90
type: kubernetes.io/dockercfg

官網提供的信息：

apiVersion: v1
data:
  .dockerconfigjson: eyJodHRwczovL2luZGV4L ... J0QUl6RTIifX0=
kind: Secret
metadata:
  ...
  name: regcred
  ...
type: kubernetes.io/dockerconfigjson

細心的朋友已經看出來了：
通過命令創建的data是.dockercfg，並且類型也不同：type: kubernetes.io/dockercfg
而官網提供的的data是.dockerconfigjson，類型是：type: kubernetes.io/dockerconfigjson

細微差別，千里之外啊，趕緊改了試一試：

root@k8s-master:~# kubectl get secret regcred  -o yaml > secret.yaml

修改之：

root@k8s-master:~# more secret.yaml
apiVersion: v1
data:
  .dockerconfigjson: eyJhdXRocyI6eyJqZC1yZXBvLmludC5hbmtlcmppZWRpYW4uY29tIjp7InVzZXJuYW1lIjoiYWRtaW4iLCJwYXNzd29yZCI6IkhhcmJvcjEyMzQ1IiwiZW1haWwiOiJ5dXhpYW9jQGp1bWVpLmNvbSIsImF1dGgiOiJZV1J0YVc0NlNHRnlZbTl5TVRJek5EVT0ifX19
kind: Secret
metadata:
  name: regcred
  namespace: default
  selfLink: /api/v1/namespaces/default/secrets/regcred
type: kubernetes.io/dockerconfigjson

然后重建之：

root@k8s-master:~# kubectl delete secret regcred
root@k8s-master:~# kubectl create -f secret.yaml
root@k8s-master:~# kubectl delete -f <(echo 'apiVersion: v1
kind: Pod
metadata:
  name: private-reg
spec:
  containers:
  - name: private-reg-container
    image: repo.mrvolleyball.com/library/busybox:latest
  imagePullSecrets:
  - name: regcred')
pod "private-reg" deleted
root@k8s-master:~# kubectl apply -f <(echo 'apiVersion: v1
kind: Pod
metadata:
  name: private-reg
spec:
  containers:
  - name: private-reg-container
    image: repo.mrvolleyball.com/library/busybox:latest
  imagePullSecrets:
  - name: regcred')
pod "private-reg" created

root@k8s-master:~# kubectl get pods private-reg
NAME          READY     STATUS    RESTARTS   AGE
private-reg   1/1       Running   0          15s

終於，達到了需要的效果

五、小結

● 再詳細的文檔也需要一步一步實踐，只有實踐了，才是自己的知識，否則就是人雲亦雲
● 看文檔一定要非常仔細，而且要對比對比在對比，如果你確定了和文檔的一樣沒問題，做出來的依然錯誤，就去提issue吧

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至此，本文結束
在下才疏學淺，有撒湯漏水的，請各位不吝賜教...