本文接上一篇介绍如何从pod内部访问kubernetes API server。 所有的pod默认都关联上一个serviceAccount，只要该serviceAccount有权限访问你访问的资源对象，就可以直接访问。
我们使用default namespace中default serviceAccount， 提前创建了一个role并将default和该role进行roleBinding。
前提
先创建role， kubectl create -f role.yaml
[root@node1 yqyaml]# cat role.yaml
kind: Role
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
namespace: default
name: pod-reader
rules:
- apiGroups: [""] # The API group "" indicates the core API Group.
resources:
- configmaps
- secrets
- nodes
- nodes/metrics
- nodes/stats
- nodes/log
- nodes/spec
- nodes/proxy
- pods
- services
- resourcequotas
- replicationcontrollers
- limitranges
- persistentvolumeclaims
- persistentvolumes
- namespaces
- endpoints
- proxy
verbs:
- list
- watch
- get
- apiGroups:
- extensions
resources:
- daemonsets
- deployments
- replicasets
- ingresses
verbs:
- list
- watch
- apiGroups:
- apps
resources:
- statefulsets
- daemonsets
- deployments
- replicasets
verbs:
- list
- watch
- apiGroups:
- batch
resources:
- cronjobs
- jobs
verbs:
- list
- watch
- apiGroups:
- autoscaling
resources:
- horizontalpodautoscalers
verbs:
- list
- watch
- apiGroups:
- authentication.k8s.io
resources:
- tokenreviews
verbs:
- create
- apiGroups:
- authorization.k8s.io
resources:
- subjectaccessreviews
verbs:
- create
nonResourceURLs: []
[root@node1 yqyaml]#
然后绑定role和serviceAccount
kubectl create -f roleBinding1.yaml
[root@node1 yqyaml]# cat roleBinding1.yaml
# This role binding allows "test-deri" to read pods in the namespace "test-deri"
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: default-role-binding
namespace: default
subjects:
- kind: ServiceAccount # May be "User", "Group" or "ServiceAccount"
name: default
roleRef:
kind: Role
name: pod-reader
apiGroup: rbac.authorization.k8s.io
[root@node1 yqyaml]#
最后检查绑定关系. 检查已经创建的role和roleBinding
[root@node1 yqyaml]# kubectl get serviceaccount
NAME SECRETS AGE
default 1 18d
myaccount2 1 8h
test1 1 4h58m
yqaccount 1 44h
[root@node1 yqyaml]# kubectl get role
NAME AGE
pod-reader 45h
pod-reader2 45h
[root@node1 yqyaml]# kubectl get rolebinding
NAME AGE
default-role-binding 45h
default-role-binding2 44h
yqaccount-role-binding2 44h
[root@node1 yqyaml]#
解释：我的kubernetes上default空间已经创建很多role和serviceAccount，你只需要确保刚才提到的role pod-reader 和 rolebinding default-role-binding 存在就行。
简单的带有curl的镜像（非必须）
我先制作了一个简单的镜像，镜像只有curl工具, 可以直接使用其他任何带有curl工具的镜像。略过本步
Dockerfile文件
FROM alpine:latest
RUN apk add --update curl && rm -rf /var/cache/apk/*
然后执行命令（在Dockerfile文件所在目录执行， 后者指定Dockerfile文件路径）
docker build -t local/curl:v1 .
执行完成后，查看生成的镜像：
[root@node1 dockerFiles]# docker images -a|grep local
local/curl v1 fa8e179516ee 46 hours ago 6.95MB
[root@node1 dockerFiles]#
pod yaml文件
可以发下明我意的pod中镜像文件是local/curl:v1， 就是刚才生成的镜像。 它的运行命令是 [ "/bin/sh", "-c", "sleep 60000" ]
[root@node1 yqyaml]# cat curlPodWithEnv.yaml
apiVersion: v1
kind: Pod
metadata:
name: curl-yqaccount-meta-status-pod
spec:
containers:
- name: test-container
image: local/curl:v1
command: [ "/bin/sh", "-c", "sleep 60000" ]
env:
- name: SPECIAL_METADATA_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: SPECIAL_HOST_IP
valueFrom:
fieldRef:
fieldPath: status.hostIP
restartPolicy: Never
[root@node1 yqyaml]#
访问 API Server
1， 先进入的pod的容器中
2， 执行 如下命令获得token
TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
3， 访问API server
其中API server的地址和端口可以通过env命令获取
curl --cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt -H "Authorization: Bearer $TOKEN" -s https://10.1.0.1:443/api/v1/namespaces/default/pods/
需要强调的是因为我的role配置的不同，导致不能直接访问https://10.1.0.1:443， 但是可以访问https://10.1.0.1:443/api/v1/namespaces/default/pods/
# curl --cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt -H "Authorization: Bearer $TOKEN" -s https://10.1.0.1:443/api
{
"kind": "APIVersions",
"versions": [
"v1"
],
"serverAddressByClientCIDRs": [
{
"clientCIDR": "0.0.0.0/0",
"serverAddress": "192.168.119.142:6443"
}
]
}/ #
还可以在pod内删除其他pod
curl -s https://10.1.0.1/api/v1/namespaces/default/pods/{xxxpod} -X DELETE -H "Authorization: Bearer $TOKEN" --cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
提示：我的default serviceAccount绑定了两个role，另外一个role是pod-reader2
[root@node1 yqyaml]# cat simpleRole.yaml
kind: Role
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
namespace: default
name: pod-reader2
rules:
- apiGroups:
- '*'
resources:
- '*'
verbs:
- '*'
如取消关联pod-reader2， 按我的default serviceaccount可以访问获取pod list但是不能删除，可以参考如下结果
curl
curl的使用方法，请参考阮一峰老师的博客，http://www.ruanyifeng.com/blog/2019/09/curl-reference.html
