全網最簡單的k8s User JWT token管理器

時間 2019-12-10

標籤全網最簡單 k8s user jwt token 管理器简体版

原文原文鏈接

kubernetes集羣三步安裝

概述

kubernetes server account的token很容易獲取，可是User的token很是麻煩，本文給出一個極簡的User token生成方式，讓用戶能夠一個http請求就能獲取到。git

token主要用來幹啥

官方dashboard登陸時須要。若是經過使用kubeconfig文件登陸而文件中又沒有token的話會失敗，如今大部分文章都介紹使用service account的token來登陸dashboard，能通，不過有問題：
第一：綁定角色時要指定類型是service account:github

apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  labels:
    k8s-app: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount   # 這裏不是User類型
  name: kubernetes-dashboard
  namespace: kube-system

第二：要理解kubeconfig裏是解析證書把CN做爲用戶名的，這時service account即使與CN同樣那仍是兩個帳戶，綁定角色時還須要綁定兩次，有點像把service account給"人"用, 因此把service account的token扔給某個開發人員去用每每不合適，service account token更多時候是給程序用的。web

想直接調用https的，沒有token就會：json

[root@iZj6cegflzze2l7fpcqoerZ ssl]# curl https://172.31.12.61:6443/api/v1/namespaces/default/pods --insecure
{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {

  },
  "status": "Failure",
  "message": "pods is forbidden: User \"system:anonymous\" cannot list resource \"pods\" in API group \"\" in the namespace \"default\"",
  "reason": "Forbidden",
  "details": {
    "kind": "pods"
  },
  "code": 403
}

由於沒有任何認證信息，因此匿名（anonymous）用戶沒有任何權限vim

加了token是這樣的：api

[root@iZj6cegflzze2l7fpcqoerZ ssl]# curl -H "Authorization: Bearer eyJhbGciOiJSUzI1NiIsImtpZCI6IkNnYzRPVEV5TlRVM0VnWm5hWFJvZFdJIn0.eyJpc3MiOiJodHRwczovL2RleC5leGFtcGxlLmNvbTo4MDgwIiwic3ViIjoiQ2djNE9URXlOVFUzRWdabmFYUm9kV0kiLCJhdWQiOiJleGFtcGxlLWFwcCIsImV4cCI6MTU1MTA5NzkwNiwiaWF0IjoxNTUwNzM3OTA2LCJlbWFpbCI6ImZodGpvYkBob3RtYWlsLmNvbSIsImVtYWlsX3ZlcmlmaWVkIjp0cnVlLCJncm91cHMiOlsiZGV2Il0sIm5hbWUiOiJmYW51eCJ9.ZqKn461UW0aGtyjyqu2Dc5tiUzC-6eYLag542d3AvklUdZuw8i9XwyaUg_f1OAj0ZsEcOybOe9_PeGMaUYzU0OvlKPY-q2zbQVC-m6u6sQw6ZXx8pi0W8k4wQSJnMaOLddCfurlYufmr8kScDBQlnKapSR0F9mJzvpKkHD-XNshQKWhX3n03g7OfFgb4RuhLjKDNQnoGn7DfBNntibHlF9sPo0jC5JjqTZaGvoGmiRE4PAXwxA-RJifsWDNf_jW8lrDiY4NSO_3O081cia4N1GKht51q9W3eaNMvFDD9hje7abDdZoz9KPi2vc3zvgH7cNv0ExVHKaA0-dwAZgTx4g" -k https://172.31.12.61:6443/api/v1/namespaces/default/pods
{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {

  },
  "status": "Failure",
  "message": "pods is forbidden: User \"https://dex.example.com:8080#fanux\" cannot list resource \"pods\" in API group \"\" in the namespace \"default\"",
  "reason": "Forbidden",
  "details": {
    "kind": "pods"
  },
  "code": 403
}

看，雖然仍是403 可是已經有了用戶信息，只要給該用戶受權就可正常訪問了，如何受權下文介紹瀏覽器

token種類介紹

token的生成方式有不少，主要分紅三種：app

service account token 這個建立service account就有，存在secret裏獲取比較簡單，可是要區分好 User 和 service account區別
普通的token，這種token就是個普通的字符串，通常是本身寫一個認證的web hook, k8s認證時調用這個hook 查詢token是否有效，比較low
基於openid的jwt(josn web token) 這種token，認證中心把用戶信息放在json裏，用私鑰加密，k8s拿到token後用公鑰解密，只要解密成功token就是合法的並且能拿到用戶信息，不須要再像認證中心請求

基於openid的jwt是本文介紹的重點。curl

社區用的比較多的就是dex,是一個比較完整的實現，可是對於不熟悉該技術的朋友來講仍是有點門檻的，容易繞進去。並且還存在一些使用不方便的問題。
如依賴複雜，首先得須要一個真正的用戶管理程序，如ldap 或者一個auth2服務端，這還能夠接受，關鍵是認證時可能須要依賴瀏覽器進行跳轉受權，這在十分多的場景裏就變的十分尷尬，就好比咱們的場景壓根沒有
界面，這樣生成token就成了一個大問題。其次集成到別的系統中時每每用戶已經登陸過了，因此須要一個二次受權的過程才能拿到token，依賴太重致使系統難以設計。
然而若是不是集成到別的系統中，好比從0開發一個完成的PaaS平臺那使用dex仍是一個完美的方案。ui

因此咱們實現了一個簡單粗暴的方案，徹底解放了這個過程, 只care最核心的東西。

sealyun fist介紹

咱們想要啥?

input:

{
    "User": "fanux",
    "Group": ["sealyun", "develop"]
}

output:

eyJhbGciOiJSUzI1NiIsImtpZCI6IkNnYzRPVEV5TlRVM0VnWm5hWFJvZFdJIn0.eyJpc3MiOiJodHRwczovL2RleC5leGFtcGxlLmNvbTo4MDgwIiwic3ViIjoiQ2djNE9URXlOVFUzRWdabmFYUm9kV0kiLCJhdWQiOiJleGFtcGxlLWFwcCIsImV4cCI6MTU1MTA5NzkwNiwiaWF0IjoxNTUwNzM3OTA2LCJlbWFpbCI6ImZodGpvYkBob3RtYWlsLmNvbSIsImVtYWlsX3ZlcmlmaWVkIjp0cnVlLCJncm91cHMiOlsiZGV2Il0sIm5hbWUiOiJmYW51eCJ9.ZqKn461UW0aGtyjyqu2Dc5tiUzC-6eYLag542d3AvklUdZuw8i9XwyaUg_f1OAj0ZsEcOybOe9_PeGMaUYzU0OvlKPY-q2zbQVC-m6u6sQw6ZXx8pi0W8k4wQSJnMaOLddCfurlYufmr8kScDBQlnKapSR0F9mJzvpKkHD-XNshQKWhX3n03g7OfFgb4RuhLjKDNQnoGn7DfBNntibHlF9sPo0jC5JjqTZaGvoGmiRE4PAXwxA-RJifsWDNf_jW8lrDiY4NSO_3O081cia4N1GKht51q9W3eaNMvFDD9hje7abDdZoz9KPi2vc3zvgH7cNv0ExVHKaA0-dwAZgTx4g

結束,多簡單，別整那麼多沒用的。

因此爲了實現上面的功能，咱們開發了 fist, fist的auth模塊把dex裏最核心的token生成功能以及jwt功能實現了。

sealyun fist/auth 使用教程

安裝部署

生成證書

# mkdir /etc/kubernetes/pki/fist
# cd /etc/kubernetes/pki/fist
# sh gencert.sh # 腳本內容內代碼

啓動fist auth模塊

kubectl create -f deploy/fist-auth.yaml

修改k8s apiserver啓動參數

vim /etc/kubernetes/manifests/kube-apiserver.yaml

- command:
    - kube-apiserver
    - --oidc-issuer-url=https://fist.sealyun.svc.cluster.local:8080
    - --oidc-client-id=example-app
    - --oidc-ca-file=/etc/kubernetes/pki/fist/ca.pem
    - --oidc-username-claim=name
    - --oidc-groups-claim=groups

獲取及使用 token

獲取token

curl https://fist.sealyun.svc.cluster.local:8080/token?user=fanux&group=sealyun,develop --cacert ca.pem

使用token

直接curl加bare token 見上文

加入到kubeconfig中:

kubectl config set-credentials --token=eyJhbGciOiJSUzI1NiIsImtpZCI6IkNnYzRPVEV5TlRVM0VnWm5hWFJvZFdJIn0.eyJpc3MiOiJodHRwczovL2RleC5leGFtcGxlLmNvbTo4MDgwIiwic3ViIjoiQ2djNE9URXlOVFUzRWdabmFYUm9kV0kiLCJhdWQiOiJleGFtcGxlLWFwcCIsImV4cCI6MTU1MTEwMDI5MywiaWF0IjoxNTUwNzQwMjkzLCJlbWFpbCI6ImZodGpvYkBob3RtYWlsLmNvbSIsImVtYWlsX3ZlcmlmaWVkIjp0cnVlLCJncm91cHMiOlsiZGV2Il0sIm5hbWUiOiJmYW51eCJ9.OAK4oIYqJszm1EACYW2neXTo738RW9kXFOIN5bOT4Z2CeKAvYqyOVKCWZf04xX45jwT78mATR3uas2YvRooDXlvxaD3K43ls4KBSG-Ofp-ynqlcVTpD3sUDqyux2iieNv4N6IyCv11smrU0lIlkrQC6oyxzTGae1FrJVGc5rHNsIRZHp2WrQvw83uLn_elHgUfSlsOq0cPtVONaAQWMAMi2DX-y5GCNpn1CDvudGJihqsTciPx7bj0AOXyiOznWhV186Ybk-Rgqn8h0eBaQhFMyNpwVt6oIP5pvJQs0uoODeRv6P3I3-AjKyuCllh9KDtlCVvSP4WtMUTfHQN4BigQ  kubernetes-admin

而後.kube/config 文件裏的 user.client-certifacate-data 和 client-key-data就能夠刪了，再執行kubectl會：

[root@iZj6cegflzze2l7fpcqoerZ ~]# kubectl get pod
Error from server (Forbidden): pods is forbidden: User "https://dex.example.com:8080#fanux" cannot list resource "pods" in API group "" in the namespace "default"

說明新用戶成功了

受權

[root@iZj6cegflzze2l7fpcqoerZ ~]# cat rolebind.yaml
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: read-secrets-global
subjects:
- kind: User
  name: "https://dex.example.com:8080#fanux" # Name is case sensitive
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: cluster-admin  # 超級用戶給他
  apiGroup: rbac.authorization.k8s.io

建立個role binding便可：

[root@iZj6cegflzze2l7fpcqoerZ ~]# kubectl  --kubeconfig /etc/kubernetes/admin.conf create  -f rolebind.yaml # 用管理員的kubeconfig
clusterrolebinding.rbac.authorization.k8s.io/read-secrets-global created
[root@iZj6cegflzze2l7fpcqoerZ ~]# kubectl get pod # 有權限訪問pod了
No resources found.

原理介紹

jwt原理

https://fist.sealyun.cluster.local:8080
k8s                                             jwt server
 |   /.well-known/openid-configuration             |
 |------------------------------------------------>|  k8s經過此url發現一些信息，最重要的就是用於校驗token公鑰的地址
 |   discover info                                 |
 |<------------------------------------------------|
 |     /keys                                       |
 |------------------------------------------------>|  上一步拿到地址，這一步獲取到公鑰
 |     public keys                                 |
 |<------------------------------------------------|
 |                                                 |

discoer info 是個json:

{
"issuer": "https://accounts.google.com",
"authorization_endpoint": "https://accounts.google.com/o/oauth2/v2/auth",
"token_endpoint": "https://oauth2.googleapis.com/token",
"userinfo_endpoint": "https://openidconnect.googleapis.com/v1/userinfo",
"revocation_endpoint": "https://oauth2.googleapis.com/revoke",
"jwks_uri": "https://www.googleapis.com/oauth2/v3/certs",
"response_types_supported": [
"code",
"token",
"id_token",
"code token",
"code id_token",
"token id_token",
"code token id_token",
"none"
],
...

public keys也是個json 相似：

{
"keys": [
{
"e": "AQAB",
"kty": "RSA",
"alg": "RS256",
"n": "3MdFK4pXPvehMipDL_COfqn6o9soHgSaq_V1o8U_5gTZ-j9DxO9PV7BVncXBgHFctnp3JQ1QTDF7txeHeuLOS4KziRw5r4ohaj2WoOTqXh7lqVMR2YDAcBK46asS177NpkQ1CqHIsy3kNfqhXLwTaKfdlwdA_XUfRbKORWbq0kDxV35egx35nHl5qJ6aP6fcpsnnPvHf7KWO0zkdvwuR-IX79HjqUAEg5UERd5FK4y06PRbxuXHjAgVhHu_sk4reNXNp1HRuTYtQ26DFbVaIjsWb8-nQC8-7FkTjlw9FteAwLVGOm9sTLFp73jAf0pWLh7sJ02pBxZKjsxLO1Lvg7w",
"use": "sig",
"kid": "7c309e3a1c1999cb0404ab7125ee40b7cdbcaf7d"
},
{
"alg": "RS256",
"n": "2K7epoJWl_B68lRUi1txaa0kEuIK4WHiHpi1yC4kPyu48d046yLlrwuvbQMbog2YTOZdVoG1D4zlWKHuVY00O80U1ocFmBl3fKVrUMakvHru0C0mAcEUQo7ItyEX7rpOVYtxlrVk6G8PY4EK61EB-Xe35P0zb2AMZn7Tvm9-tLcccqYlrYBO4SWOwd5uBSqc_WcNJXgnQ-9sYEZ0JUMhKZelEMrpX72hslmduiz-LMsXCnbS7jDGcUuSjHXVLM9tb1SQynx5Xz9xyGeN4rQLnFIKvgwpiqnvLpbMo6grhJwrz67d1X6MwpKtAcqZ2V2v4rQsjbblNH7GzF8ZsfOaqw",
"use": "sig",
"kid": "7d680d8c70d44e947133cbd499ebc1a61c3d5abc",
"e": "AQAB",
"kty": "RSA"
}
]
}

因此fist只須要實現這兩個url 和用私鑰匙加密用戶信息生成token便可。

建立密鑰對:

key, err := rsa.GenerateKey(rand.Reader, 2048)
    if err != nil {
        log.Fatalf("gen rsa key: %v", err)
    }
    priv = jose.JSONWebKey{
        Key:       key,
        KeyID:     "Cgc4OTEyNTU3EgZnaXRodWI",
        Algorithm: "RS256",
        Use:       "sig",
    }
    pub = jose.JSONWebKey{
        Key:       key.Public(),
        KeyID:     "Cgc4OTEyNTU3EgZnaXRodWI",
        Algorithm: "RS256",
        Use:       "sig",
    }

私鑰加密：

tok := idTokenClaims{
        Issuer:        "https://dex.example.com:8080",
        Subject:       "Cgc4OTEyNTU3EgZnaXRodWI",
        Audience:      "example-app",
        Expiry:        time.Now().Add(time.Hour * 100).Unix(),
        IssuedAt:      time.Now().Unix(),
        Email:         "fhtjob@hotmail.com",
        EmailVerified: &ev,
        Groups:        []string{"dev"},
        Name:          "fanux",
    }

    payload, err := json.Marshal(&tok)
    if err != nil {
        return
    }

    var idToken string
    if idToken, err = signPayload(&Priv, signingAlg, payload); err != nil {
        return