Curl 无法使用 kubernetes dns 解析主机

Question

您好，我在 kubernetes 中遇到了问题。当我从 pod 执行 nslookup 时，我得到正确的 ip:

~ kubectl -n exampleNamespace exec -it pod/curl -- nslookup exampleService.exampleNamespace
Defaulting container name to curl.
Use 'kubectl describe pod/curl -n exampleNamespace' to see all of the containers in this pod.
Server:     192.168.3.10
Address:    192.168.3.10:53

** server can't find exampleService.exampleNamespace: NXDOMAIN

Non-authoritative answer:
Name:   exampleService.exampleNamespace
Address: 192.168.3.64

command terminated with exit code 1

192.168.3.64 是正确的 ip，但是当我尝试从同一命名空间中的 pod 卷曲此 DNS 时，我得到以下信息：

~ kubectl -n exampleNamespace exec -it pod/curl -- curl http://exampleService.exampleNamespace/path
Defaulting container name to curl.
Use 'kubectl describe pod/curl -n exampleNamespace' to see all of the containers in this pod.
curl: (6) Could not resolve host: exampleService.exampleNamespace
command terminated with exit code 6

Curl pod 使用以下 yaml 启动：

apiVersion: v1
kind: Pod
metadata:
  name: curl
  namespace: exampleNamespace
spec:
  containers:
  - image: curlimages/curl
    command:
      - sleep
      - "3600"
    imagePullPolicy: IfNotPresent
    name: curl
  restartPolicy: Always

Answer 1

原来将图像从 curlimages/curl 交换到 buildpack-deps:curl 解决了问题，但我不知道为什么。

工作 yaml：

apiVersion: v1
kind: Pod
metadata:
  name: curl
  namespace: exampleNamespace
spec:
  containers:
  - image: buildpack-deps:curl
    command:
      - sleep
      - "3600"
    imagePullPolicy: IfNotPresent
    name: curl
  restartPolicy: Always

Answer 2

据一些网站报道，Alpine 和 Kubernetes dns 解析似乎存在一些问题：

https://www.openwall.com/lists/musl/2018/03/30/9
Does Alpine have known DNS issue within Kubernetes?
https://github.com/gliderlabs/docker-alpine/issues/8
https://github.com/kubernetes/kubernetes/issues/30215

使用图像 curlimages/curl:7.77.0 按预期工作。

Curl 无法使用 kubernetes dns 解析主机

Curl cant resolve host with kubernetes dns

dns

curl

kubernetes