Move Guide topic: Master-Node Communication. (#3098)

2017-03-29 09:20:12 -07:00
parent 750f9323c5
commit dfd2fed09c
3 changed files with 110 additions and 98 deletions
@@ -52,6 +52,7 @@ toc:
  - docs/concepts/cluster-administration/sysctl-cluster.md
  - docs/concepts/cluster-administration/access-cluster.md
  - docs/concepts/cluster-administration/authenticate-across-clusters-kubeconfig.md
  - docs/concepts/cluster-administration/master-node-communication.md
 - title: Storage
  section:
@@ -3,104 +3,9 @@ assignees:
 - dchen1107
 - roberthbailey
 - liggitt
-title: Master-Node communication
+title: Master-Node Communication
 ---
-* TOC
+{% include user-guide-content-moved.md %}
 {:toc}
-## Overview
+[Master-Node Communication](/docs/concepts/cluster-administration/master-node-communication/)
 This document catalogs the communication paths between the master (really the
 apiserver) and the Kubernetes cluster. The intent is to allow users to
 customize their installation to harden the network configuration such that
 the cluster can be run on an untrusted network (or on fully public IPs on a
 cloud provider).
 ## Cluster -> Master
 All communication paths from the cluster to the master terminate at the
 apiserver (none of the other master components are designed to expose remote
 services). In a typical deployment, the apiserver is configured to listen for
 remote connections on a secure HTTPS port (443) with one or more forms of
 client [authentication](/docs/admin/authentication/) enabled. One or more forms
 of [authorization](/docs/admin/authorization/) should be enabled, especially
 if [anonymous requests](/docs/admin/authentication/#anonymous-requests) or 
 [service account tokens](/docs/admin/authentication/#service-account-tokens) 
 are allowed.
 Nodes should be provisioned with the public root certificate for the cluster
 such that they can connect securely to the apiserver along with valid client
 credentials. For example, on a default GCE deployment, the client credentials
 provided to the kubelet are in the form of a client certificate. See 
 [kubelet TLS bootstrapping](/docs/admin/kubelet-tls-bootstrapping/) for 
 automated provisioning of kubelet client certificates. 
 Pods that wish to connect to the apiserver can do so securely by leveraging a 
 service account so that Kubernetes will automatically inject the public root
 certificate and a valid bearer token into the pod when it is instantiated.
 The `kubernetes` service (in all namespaces) is configured with a virtual IP
 address that is redirected (via kube-proxy) to the HTTPS endpoint on the
 apiserver.
 The master components communicate with the cluster apiserver over the
 insecure (not encrypted or authenticated) port. This port is typically only
 exposed on the localhost interface of the master machine, so that the master
 components, all running on the same machine, can communicate with the
 cluster apiserver. Over time, the master components will be migrated to use
 the secure port with authentication and authorization (see
 [#13598](https://github.com/kubernetes/kubernetes/issues/13598)).
 As a result, the default operating mode for connections from the cluster
 (nodes and pods running on the nodes) to the master is secured by default
 and can run over untrusted and/or public networks.
 ## Master -> Cluster
 There are two primary communication paths from the master (apiserver) to the
 cluster. The first is from the apiserver to the kubelet process which runs on
 each node in the cluster. The second is from the apiserver to any node, pod,
 or service through the apiserver's proxy functionality.
 ### apiserver -> kubelet
 The connections from the apiserver to the kubelet are used for fetching logs
 for pods, attaching (through kubectl) to running pods, and using the kubelet's
 port-forwarding functionality. These connections terminate at the kubelet's 
 HTTPS endpoint.
 By default, the apiserver does not verify the kubelet's serving certificate,
 which makes the connection subject to man-in-the-middle attacks, and 
 **unsafe** to run over untrusted and/or public networks.
 To verify this connection, use the `--kubelet-certificate-authority` flag to 
 provide the apiserver with a root certificates bundle to use to verify the 
 kubelet's serving certificate.
 If that is not possible, use [SSH tunneling](/docs/admin/master-node-communication/#ssh-tunnels)
 between the apiserver and kubelet if required to avoid connecting over an 
 untrusted or public network.
 Finally, [Kubelet authentication and/or authorization](/docs/admin/kubelet-authentication-authorization/)
 should be enabled to secure the kubelet API. 
 ### apiserver -> nodes, pods, and services
 The connections from the apiserver to a node, pod, or service default to plain
 HTTP connections and are therefore neither authenticated nor encrypted. They
 can be run over a secure HTTPS connection by prefixing `https:` to the node,
 pod, or service name in the API URL, but they will not validate the certificate
 provided by the HTTPS endpoint nor provide client credentials so while the
 connection will be encrypted, it will not provide any guarantees of integrity.
 These connections **are not currently safe** to run over untrusted and/or
 public networks.
 ### SSH Tunnels
 [Google Container Engine](https://cloud.google.com/container-engine/docs/) uses
 SSH tunnels to protect the Master -> Cluster communication paths. In this
 configuration, the apiserver initiates an SSH tunnel to each node in the
 cluster (connecting to the ssh server listening on port 22) and passes all
 traffic destined for a kubelet, node, pod, or service through the tunnel.
 This tunnel ensures that the traffic is not exposed outside of the private
 GCE network in which the cluster is running.
@@ -0,0 +1,106 @@
 ---
 assignees:
 - dchen1107
 - roberthbailey
 - liggitt
 title: Master-Node communication
 ---
 * TOC
 {:toc}
 ## Overview
 This document catalogs the communication paths between the master (really the
 apiserver) and the Kubernetes cluster. The intent is to allow users to
 customize their installation to harden the network configuration such that
 the cluster can be run on an untrusted network (or on fully public IPs on a
 cloud provider).
 ## Cluster -> Master
 All communication paths from the cluster to the master terminate at the
 apiserver (none of the other master components are designed to expose remote
 services). In a typical deployment, the apiserver is configured to listen for
 remote connections on a secure HTTPS port (443) with one or more forms of
 client [authentication](/docs/admin/authentication/) enabled. One or more forms
 of [authorization](/docs/admin/authorization/) should be enabled, especially
 if [anonymous requests](/docs/admin/authentication/#anonymous-requests) or 
 [service account tokens](/docs/admin/authentication/#service-account-tokens) 
 are allowed.
 Nodes should be provisioned with the public root certificate for the cluster
 such that they can connect securely to the apiserver along with valid client
 credentials. For example, on a default GCE deployment, the client credentials
 provided to the kubelet are in the form of a client certificate. See 
 [kubelet TLS bootstrapping](/docs/admin/kubelet-tls-bootstrapping/) for 
 automated provisioning of kubelet client certificates. 
 Pods that wish to connect to the apiserver can do so securely by leveraging a 
 service account so that Kubernetes will automatically inject the public root
 certificate and a valid bearer token into the pod when it is instantiated.
 The `kubernetes` service (in all namespaces) is configured with a virtual IP
 address that is redirected (via kube-proxy) to the HTTPS endpoint on the
 apiserver.
 The master components communicate with the cluster apiserver over the
 insecure (not encrypted or authenticated) port. This port is typically only
 exposed on the localhost interface of the master machine, so that the master
 components, all running on the same machine, can communicate with the
 cluster apiserver. Over time, the master components will be migrated to use
 the secure port with authentication and authorization (see
 [#13598](https://github.com/kubernetes/kubernetes/issues/13598)).
 As a result, the default operating mode for connections from the cluster
 (nodes and pods running on the nodes) to the master is secured by default
 and can run over untrusted and/or public networks.
 ## Master -> Cluster
 There are two primary communication paths from the master (apiserver) to the
 cluster. The first is from the apiserver to the kubelet process which runs on
 each node in the cluster. The second is from the apiserver to any node, pod,
 or service through the apiserver's proxy functionality.
 ### apiserver -> kubelet
 The connections from the apiserver to the kubelet are used for fetching logs
 for pods, attaching (through kubectl) to running pods, and using the kubelet's
 port-forwarding functionality. These connections terminate at the kubelet's 
 HTTPS endpoint.
 By default, the apiserver does not verify the kubelet's serving certificate,
 which makes the connection subject to man-in-the-middle attacks, and 
 **unsafe** to run over untrusted and/or public networks.
 To verify this connection, use the `--kubelet-certificate-authority` flag to 
 provide the apiserver with a root certificates bundle to use to verify the 
 kubelet's serving certificate.
 If that is not possible, use [SSH tunneling](/docs/admin/master-node-communication/#ssh-tunnels)
 between the apiserver and kubelet if required to avoid connecting over an 
 untrusted or public network.
 Finally, [Kubelet authentication and/or authorization](/docs/admin/kubelet-authentication-authorization/)
 should be enabled to secure the kubelet API. 
 ### apiserver -> nodes, pods, and services
 The connections from the apiserver to a node, pod, or service default to plain
 HTTP connections and are therefore neither authenticated nor encrypted. They
 can be run over a secure HTTPS connection by prefixing `https:` to the node,
 pod, or service name in the API URL, but they will not validate the certificate
 provided by the HTTPS endpoint nor provide client credentials so while the
 connection will be encrypted, it will not provide any guarantees of integrity.
 These connections **are not currently safe** to run over untrusted and/or
 public networks.
 ### SSH Tunnels
 [Google Container Engine](https://cloud.google.com/container-engine/docs/) uses
 SSH tunnels to protect the Master -> Cluster communication paths. In this
 configuration, the apiserver initiates an SSH tunnel to each node in the
 cluster (connecting to the ssh server listening on port 22) and passes all
 traffic destined for a kubelet, node, pod, or service through the tunnel.
 This tunnel ensures that the traffic is not exposed outside of the private
 GCE network in which the cluster is running.