无法从pod内部ping ClusterIP,DNS无法用于google.com等外部域

Question

我在Bare-metal/Ubuntu上安装了Kubernetes.我正在使用6b649d7f9f2b09ca8b0dd8c0d3e14dcb255432d1git.我用cd kubernetes/cluster; KUBERNETES_PROVIDER=ubuntu ./kube-up.sh后来cd kubernetes/cluster/ubuntu; ./deployAddons.sh启动集群.一切都很顺利,集群起来了.

我的/ubuntu/config-default.sh情况如下:

# Define all your cluster nodes, MASTER node comes first"
# And separated with blank space like <user_1@ip_1> <user_2@ip_2> <user_3@ip_3> 
export nodes=${nodes:-"root@192.168.48.170 root@192.168.48.180"}

# Define all your nodes role: a(master) or i(minion) or ai(both master and minion), must be the order same 
role=${role:-"ai i"}
# If it practically impossible to set an array as an environment variable
# from a script, so assume variable is a string then convert it to an array
export roles=($role)

# Define minion numbers
export NUM_NODES=${NUM_NODES:-2}
# define the IP range used for service cluster IPs.
# according to rfc 1918 ref: https://tools.ietf.org/html/rfc1918 choose a private ip range here.
export SERVICE_CLUSTER_IP_RANGE=${SERVICE_CLUSTER_IP_RANGE:-192.168.3.0/24}  # formerly PORTAL_NET
# define the IP range used for flannel overlay network, should not conflict with above SERVICE_CLUSTER_IP_RANGE
export FLANNEL_NET=${FLANNEL_NET:-172.16.0.0/16}

# Optionally add other contents to the Flannel configuration JSON
# object normally stored in etcd as /coreos.com/network/config.  Use
# JSON syntax suitable for insertion into a JSON object constructor
# after other field name:value pairs.  For example:
# FLANNEL_OTHER_NET_CONFIG=', "SubnetMin": "172.16.10.0", "SubnetMax": "172.16.90.0"'

export FLANNEL_OTHER_NET_CONFIG
FLANNEL_OTHER_NET_CONFIG=''

# Admission Controllers to invoke prior to persisting objects in cluster
export ADMISSION_CONTROL=NamespaceLifecycle,LimitRanger,ServiceAccount,ResourceQuota,SecurityContextDeny

# Path to the config file or directory of files of kubelet
export KUBELET_CONFIG=${KUBELET_CONFIG:-""}

# A port range to reserve for services with NodePort visibility
SERVICE_NODE_PORT_RANGE=${SERVICE_NODE_PORT_RANGE:-"30000-32767"}

# Optional: Enable node logging.
ENABLE_NODE_LOGGING=false
LOGGING_DESTINATION=${LOGGING_DESTINATION:-elasticsearch}

# Optional: When set to true, Elasticsearch and Kibana will be setup as part of the cluster bring up.
ENABLE_CLUSTER_LOGGING=false
ELASTICSEARCH_LOGGING_REPLICAS=${ELASTICSEARCH_LOGGING_REPLICAS:-1}

# Optional: When set to true, heapster, Influxdb and Grafana will be setup as part of the cluster bring up.
ENABLE_CLUSTER_MONITORING="${KUBE_ENABLE_CLUSTER_MONITORING:-true}"

# Extra options to set on the Docker command line.  This is useful for setting
# --insecure-registry for local registries.
DOCKER_OPTS=${DOCKER_OPTS:-""}

# Extra options to set on the kube-proxy command line.  This is useful
# for selecting the iptables proxy-mode, for example.
KUBE_PROXY_EXTRA_OPTS=${KUBE_PROXY_EXTRA_OPTS:-""}

# Optional: Install cluster DNS.
ENABLE_CLUSTER_DNS="${KUBE_ENABLE_CLUSTER_DNS:-true}"
# DNS_SERVER_IP must be a IP in SERVICE_CLUSTER_IP_RANGE
DNS_SERVER_IP=${DNS_SERVER_IP:-"192.168.3.10"}
DNS_DOMAIN=${DNS_DOMAIN:-"cluster.local"}
DNS_REPLICAS=${DNS_REPLICAS:-1}

# Optional: Install Kubernetes UI
ENABLE_CLUSTER_UI="${KUBE_ENABLE_CLUSTER_UI:-true}"

# Optional: Enable setting flags for kube-apiserver to turn on behavior in active-dev
RUNTIME_CONFIG="--basic-auth-file=password.csv"

# Optional: Add http or https proxy when download easy-rsa.
# Add envitonment variable separated with blank space like "http_proxy=http://10.x.x.x:8080 https_proxy=https://10.x.x.x:8443"
PROXY_SETTING=${PROXY_SETTING:-""}

DEBUG=${DEBUG:-"false"}

然后,我使用以下yml文件创建了一个pod:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80

并使用以下yml的服务:

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  ports:
  - port: 8000
    targetPort: 80
    protocol: TCP
  selector:
    app: nginx
  type: NodePort

然后,我进入了启动的集装箱码头docker exec -it [CONTAINER_ID] bash.主要有两个问题:

1. 我无法ping google.com等外部域名,但我可以ping外部IP,如8.8.8.8.所以容器有互联网接入.
2. 内部服务决定纠正内部ClusterIPs,但我无法从容器内部ping该IP.

主机的/etc/resolve.conf文件如下:

nameserver 8.8.8.8
nameserver 127.0.1.1

容器的/etc/resolve.conf文件如下:

search default.svc.cluster.local svc.cluster.local cluster.local
nameserver 192.168.3.10
nameserver 8.8.8.8
nameserver 127.0.1.1
options ndots:5

关于第一个问题,我认为它可能与SkyDNS名称服务器misconfigurarion或我必须做的自定义配置有关,但我不知道.

但是,我不知道容器为什么不能ping ClusterIPs.

任何解决方法？

Answer 1

我可以回答你的ping clusterIP问题。我遇到了同样的问题，想从Pod ping服务的群集IP。

解决方案似乎无法对群集IP进行ping操作，但是可以使用带有端口的curl来访问端点。

我只是在寻找有关ping虚拟IP的详细信息。

Answer 2

我找到了一个解决方法。SkyDNS 文档中的命令行参数部分，特别是“名称服务器”参数意味着：

名称服务器：当对域不具有权威性时，将 DNS 请求转发到这些（递归）名称服务器（IP:端口组合数组）。默认为 /etc/resolv.conf 中列出的服务器

但事实并非如此！要解决此问题，应更改 dns addon 复制控制器配置文件 (cluster/addons/dns/skydns-rc.yaml.in) 以包含名称服务器配置。我按如下方式更改了 skydns 容器部分，它的效果非常好。

  - name: skydns
    image: gcr.io/google_containers/skydns:2015-10-13-8c72f8c
    resources:
      # keep request = limit to keep this container in guaranteed class
      limits:
        cpu: 100m
        memory: 50Mi
      requests:
        cpu: 100m
        memory: 50Mi
    args:
    # command = "/skydns"
    - -machines=http://127.0.0.1:4001
    - -addr=0.0.0.0:53
    - -nameservers=8.8.8.8:53
    - -ns-rotate=false
    - -domain={{ pillar['dns_domain'] }}.
    ports:
    - containerPort: 53
      name: dns
      protocol: UDP
    - containerPort: 53
      name: dns-tcp
      protocol: TCP
    livenessProbe:
      httpGet:
        path: /healthz
        port: 8080
        scheme: HTTP
      initialDelaySeconds: 30
      timeoutSeconds: 5
    readinessProbe:
      httpGet:
        path: /healthz
        port: 8080
        scheme: HTTP
      initialDelaySeconds: 1
      timeoutSeconds: 5