Merge pull request #17761 from gmarek/flannel

cluster/gce/config-default.sh

@@ -113,7 +113,7 @@ ADMISSION_CONTROL=NamespaceLifecycle,LimitRanger,ServiceAccount,ResourceQuota
 KUBE_UP_AUTOMATIC_CLEANUP=${KUBE_UP_AUTOMATIC_CLEANUP:-false}
 
 # OpenContrail networking plugin specific settings
-NETWORK_PROVIDER="${NETWORK_PROVIDER:-none}" # opencontrail
+NETWORK_PROVIDER="${NETWORK_PROVIDER:-none}" # opencontrail, flannel
 OPENCONTRAIL_TAG="${OPENCONTRAIL_TAG:-R2.20}"
 OPENCONTRAIL_KUBERNETES_TAG="${OPENCONTRAIL_KUBERNETES_TAG:-master}"
 OPENCONTRAIL_PUBLIC_SUBNET="${OPENCONTRAIL_PUBLIC_SUBNET:-10.1.0.0/16}"

cluster/gce/config-test.sh

@@ -125,7 +125,7 @@ KUBE_UP_AUTOMATIC_CLEANUP=${KUBE_UP_AUTOMATIC_CLEANUP:-false}
 TEST_CLUSTER="${TEST_CLUSTER:-true}"
 
 # OpenContrail networking plugin specific settings
-NETWORK_PROVIDER="${NETWORK_PROVIDER:-none}" # opencontrail
+NETWORK_PROVIDER="${NETWORK_PROVIDER:-none}" # opencontrail,flannel
 OPENCONTRAIL_TAG="${OPENCONTRAIL_TAG:-R2.20}"
 OPENCONTRAIL_KUBERNETES_TAG="${OPENCONTRAIL_KUBERNETES_TAG:-master}"
 OPENCONTRAIL_PUBLIC_SUBNET="${OPENCONTRAIL_PUBLIC_SUBNET:-10.1.0.0/16}"

cluster/saltbase/salt/flannel-server/flannel-server.manifest

+{
+    "kind": "Pod",
+    "apiVersion": "v1",
+    "metadata": {
+        "name": "flannel-server",
+        "namespace": "kube-system",
+        "labels": {
+            "app": "flannel-server",
+            "version": "v0.1"
+        }
+    },
+    "spec": {
+        "volumes": [
+            {
+                "name": "varlog",
+                "hostPath": {
+                    "path": "/var/log"
+                }
+            },
+            {
+                "name": "etcdstorage",
+                "emptyDir": {}
+            },
+            {
+                "name": "networkconfig",
+                "hostPath": {
+                    "path": "/etc/kubernetes/network.json"
+                }
+            }
+        ],
+        "containers": [
+            {
+                "name": "flannel-server-helper",
+                "image": "gcr.io/google_containers/flannel-server-helper:0.1",
+                "args": [
+                    "--network-config=/etc/kubernetes/network.json",
+                    "--etcd-prefix=/kubernetes.io/network",
+                    "--etcd-server=http://127.0.0.1:4001"
+                ],
+                "volumeMounts": [
+                    {
+                        "name": "networkconfig",
+                        "mountPath": "/etc/kubernetes/network.json"
+                    }
+                ],
+                "imagePullPolicy": "Always"
+            },
+            {
+                "name": "flannel-container",
+                "image": "quay.io/coreos/flannel:0.5.5",
+                "command": [
+                    "/bin/sh",
+                    "-c",
+                    "/opt/bin/flanneld -listen 0.0.0.0:10253 -etcd-endpoints http://127.0.0.1:4001 -etcd-prefix /kubernetes.io/network 1>>/var/log/flannel_server.log 2>&1"
+                ],
+                "ports": [
+                    {
+                        "hostPort": 10253,
+                        "containerPort": 10253
+                    }
+                ],
+                "resources": {
+                    "limits": {
+                        "cpu": "100m"
+                    }
+                },
+                "volumeMounts": [
+                    {
+                        "name": "varlog",
+                        "mountPath": "/var/log"
+                    }
+                ]
+            },
+            {
+                "name": "etcd-container",
+                "image": "gcr.io/google_containers/etcd:2.2.1",
+                "command": [
+                    "/bin/sh",
+                    "-c",
+                    "/opt/bin/etcd --listen-peer-urls http://127.0.0.1:4001 --addr http://127.0.0.1:4001 --bind-addr 127.0.0.1:4001 --data-dir /var/etcd/data 1>>/var/log/etcd_flannel.log 2>&1"
+                ],
+                "resources": {
+                    "limits": {
+                        "cpu": "100m",
+                        "memory": "50Mi"
+                    }
+                },
+                "volumeMounts": [
+                    {
+                        "name": "etcdstorage",
+                        "mountPath": "/var/etcd/data"
+                    }
+                ]
+            }
+        ],
+        "hostNetwork": true
+    }
+}
+

cluster/saltbase/salt/flannel-server/init.sls

+touch /var/log/flannel.log:
+  cmd.run:
+    - creates: /var/log/flannel.log
+
+touch /var/log/etcd_flannel.log:
+  cmd.run:
+    - creates: /var/log/etcd_flannel.log
+
+/etc/kubernetes/network.json:
+  file.managed:
+    - source: salt://flannel-server/network.json
+    - makedirs: True
+    - user: root
+    - group: root
+    - mode: 755
+
+/etc/kubernetes/manifests/flannel-server.manifest:
+  file.managed:
+    - source: salt://flannel-server/flannel-server.manifest
+    - user: root
+    - group: root
+    - mode: 644
+    - makedirs: true
+    - dir_mode: 755

cluster/saltbase/salt/flannel-server/network.json

+{
+    "Network": "172.16.0.0/12",
+    "SubnetLen": 24,
+    "Backend": {
+        "Type": "vxlan",
+        "VNI": 1
+     }
+}

cluster/saltbase/salt/flannel/default

+{% if grains.api_servers is defined -%}
+  {% set daemon_args = "-remote " + grains.api_servers + ":10253" -%}
+{% else -%}
+  {% set daemon_args = "-remote 127.0.0.1:10253" -%}
+{% endif -%}
+DAEMON_ARGS="{{daemon_args}}"

cluster/saltbase/salt/flannel/init.sls

+# TODO: Run flannel daemon in a static pod once we've moved the overlay network
+# setup into a network plugin.
+flannel-tar:
+  archive:
+    - extracted
+    - user: root
+    - name: /usr/local/src
+    - makedirs: True
+    - source: https://github.com/coreos/flannel/releases/download/v0.5.5/flannel-0.5.5-linux-amd64.tar.gz
+    - tar_options: v
+    - source_hash: md5=972c717254775bef528f040af804f2cc
+    - archive_format: tar
+    - if_missing: /usr/local/src/flannel/flannel-0.5.5/
+
+flannel-symlink:
+  file.symlink:
+    - name: /usr/local/bin/flanneld
+    - target: /usr/local/src/flannel-0.5.5/flanneld
+    - force: true
+    - watch:
+        - archive: flannel-tar
+
+/etc/default/flannel:
+  file.managed:
+    - source: salt://flannel/default
+    - template: jinja
+    - user: root
+    - group: root
+    - mode: 644
+
+/etc/init.d/flannel:
+  file.managed:
+    - source: salt://flannel/initd
+    - user: root
+    - group: root
+    - mode: 755
+
+flannel:
+  service.running:
+    - enable: True
+    - watch:
+      - file: /usr/local/bin/flanneld
+      - file: /etc/init.d/flannel
+      - file: /etc/default/flannel

cluster/saltbase/salt/flannel/initd

+#!/bin/bash
+#
+### BEGIN INIT INFO
+# Provides:   flanneld
+# Required-Start:    $local_fs $network $syslog
+# Required-Stop:
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: Flannel daemon
+# Description:
+#   Flannel daemon.
+### END INIT INFO
+
+
+# PATH should only include /usr/* if it runs after the mountnfs.sh script
+PATH=/sbin:/usr/sbin:/bin:/usr/bin
+DESC="Flannel overlay network daemon"
+NAME=flannel
+DAEMON=/usr/local/bin/flanneld
+DAEMON_ARGS=""
+DAEMON_LOG_FILE=/var/log/$NAME.log
+PIDFILE=/var/run/$NAME.pid
+SCRIPTNAME=/etc/init.d/$NAME
+DAEMON_USER=root
+
+# Exit if the package is not installed
+[ -x "$DAEMON" ] || exit 0
+
+# Read configuration variable file if it is present
+[ -r /etc/default/$NAME ] && . /etc/default/$NAME
+
+# Define LSB log_* functions.
+# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
+# and status_of_proc is working.
+. /lib/lsb/init-functions
+
+#
+# Function that starts the daemon/service
+#
+do_start()
+{
+        # Avoid a potential race at boot time when both monit and init.d start
+        # the same service
+        PIDS=$(pidof $DAEMON)
+        for PID in ${PIDS}; do
+            kill -9 $PID
+	done
+
+        # Return
+        #   0 if daemon has been started
+        #   1 if daemon was already running
+        #   2 if daemon could not be started
+        start-stop-daemon --start --quiet --background --no-close \
+                --make-pidfile --pidfile $PIDFILE \
+                --exec $DAEMON -c $DAEMON_USER --test > /dev/null \
+                || return 1
+        start-stop-daemon --start --quiet --background --no-close \
+                --make-pidfile --pidfile $PIDFILE \
+                --exec $DAEMON -c $DAEMON_USER -- \
+                $DAEMON_ARGS >> $DAEMON_LOG_FILE 2>&1 \
+                || return 2
+}
+
+#
+# Function that stops the daemon/service
+#
+do_stop()
+{
+        # Return
+        #   0 if daemon has been stopped
+        #   1 if daemon was already stopped
+        #   2 if daemon could not be stopped
+        #   other if a failure occurred
+        start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --pidfile $PIDFILE --name $NAME
+        RETVAL="$?"
+        [ "$RETVAL" = 2 ] && return 2
+        # Many daemons don't delete their pidfiles when they exit.
+        rm -f $PIDFILE
+        return "$RETVAL"
+}
+
+
+case "$1" in
+  start)
+        log_daemon_msg "Starting $DESC" "$NAME"
+        do_start
+        case "$?" in
+                0|1) log_end_msg 0 || exit 0 ;;
+                2) log_end_msg 1 || exit 1 ;;
+        esac
+        ;;
+  stop)
+        log_daemon_msg "Stopping $DESC" "$NAME"
+        do_stop
+        case "$?" in
+                0|1) log_end_msg 0 ;;
+                2) exit 1 ;;
+        esac
+        ;;
+  status)
+        status_of_proc -p $PIDFILE "$DAEMON" "$NAME" && exit 0 || exit $?
+        ;;
+
+  restart|force-reload)
+        log_daemon_msg "Restarting $DESC" "$NAME"
+        do_stop
+        case "$?" in
+          0|1)
+                do_start
+                case "$?" in
+                        0) log_end_msg 0 ;;
+                        1) log_end_msg 1 ;; # Old process is still running
+                        *) log_end_msg 1 ;; # Failed to start
+                esac
+                ;;
+          *)
+                # Failed to stop
+                log_end_msg 1
+                ;;
+        esac
+        ;;
+  *)
+        echo "Usage: $SCRIPTNAME {start|stop|status|restart|force-reload}" >&2
+        exit 3
+        ;;
+esac

cluster/saltbase/salt/kube-controller-manager/kube-controller-manager.manifest

@@ -10,7 +10,11 @@
 {% if pillar['cluster_cidr'] is defined and pillar['cluster_cidr'] != "" -%}
   {% set cluster_cidr = "--cluster-cidr=" + pillar['cluster_cidr'] -%}
 {% endif -%}
-{% if pillar['allocate_node_cidrs'] is defined -%}
+# When we're using flannel it is responsible for cidr allocation.
+# This is expected to be a short-term compromise.
+{% if pillar.get('network_provider', '').lower() == 'flannel' %}
+  {% set allocate_node_cidrs = "--allocate-node-cidrs=false" -%}
+{% elif pillar['allocate_node_cidrs'] is defined -%}
   {% set allocate_node_cidrs = "--allocate-node-cidrs=" + pillar['allocate_node_cidrs'] -%}
 {% endif -%}
 {% if pillar['terminated_pod_gc_threshold'] is defined -%}

cluster/saltbase/salt/kubelet/default

@@ -85,6 +85,11 @@
   {% set configure_cbr0 = "--configure-cbr0=" + pillar['allocate_node_cidrs'] -%}
 {% endif -%}
 
+{% set experimental_flannel_overlay = "" -%}
+{% if pillar.get('network_provider', '').lower() == 'flannel' %}
+  {% set experimental_flannel_overlay = "--experimental-flannel-overlay=true" %}
+{% endif -%}
+
 # Run containers under the root cgroup and create a system container.
 {% set system_container = "" -%}
 {% set cgroup_root = "" -%}
@@ -117,4 +122,4 @@
 {% endif -%}
 
 # test_args has to be kept at the end, so they'll overwrite any prior configuration
-DAEMON_ARGS="{{daemon_args}} {{api_servers_with_port}} {{debugging_handlers}} {{hostname_override}} {{cloud_provider}} {{config}} {{manifest_url}} --allow-privileged={{pillar['allow_privileged']}} {{pillar['log_level']}} {{cluster_dns}} {{cluster_domain}} {{docker_root}} {{kubelet_root}} {{configure_cbr0}} {{cgroup_root}} {{system_container}} {{pod_cidr}} {{ master_kubelet_args }} {{cpu_cfs_quota}} {{network_plugin}} {{test_args}}"
+DAEMON_ARGS="{{daemon_args}} {{api_servers_with_port}} {{debugging_handlers}} {{hostname_override}} {{cloud_provider}} {{config}} {{manifest_url}} --allow-privileged={{pillar['allow_privileged']}} {{pillar['log_level']}} {{cluster_dns}} {{cluster_domain}} {{docker_root}} {{kubelet_root}} {{configure_cbr0}} {{cgroup_root}} {{system_container}} {{pod_cidr}} {{ master_kubelet_args }} {{cpu_cfs_quota}} {{network_plugin}} {{experimental_flannel_overlay}} {{test_args}}"

cluster/saltbase/salt/top.sls

@@ -13,6 +13,9 @@ base:
   'roles:kubernetes-pool':
     - match: grain
     - docker
+{% if pillar.get('network_provider', '').lower() == 'flannel' %}
+    - flannel
+{% endif %}
     - helpers
     - cadvisor
     - kube-client-tools
@@ -40,6 +43,10 @@ base:
     - match: grain
     - generate-cert
     - etcd
+{% if pillar.get('network_provider', '').lower() == 'flannel' %}
+    - flannel-server
+    - flannel
+{% endif %}
     - kube-apiserver
     - kube-controller-manager
     - kube-scheduler

cmd/kube-controller-manager/app/controllermanager.go

@@ -300,6 +300,8 @@ func (s *CMServer) Run(_ []string) error {
 			routeController := routecontroller.New(routes, kubeClient, s.ClusterName, &s.ClusterCIDR)
 			routeController.Run(s.NodeSyncPeriod)
 		}
+	} else {
+		glog.Infof("allocate-node-cidrs set to %v, node controller not creating routes", s.AllocateNodeCIDRs)
 	}
 
 	resourcequotacontroller.NewResourceQuotaController(kubeClient).Run(s.ResourceQuotaSyncPeriod)

cmd/kubelet/app/server.go

@@ -67,7 +67,10 @@ import (
 	"k8s.io/kubernetes/pkg/cloudprovider"
 )
 
-const defaultRootDir = "/var/lib/kubelet"
+const (
+	defaultRootDir             = "/var/lib/kubelet"
+	experimentalFlannelOverlay = false
+)
 
 // KubeletServer encapsulates all of the parameters necessary for starting up
 // a kubelet. These can either be set via command line or directly.
@@ -154,7 +157,8 @@ type KubeletServer struct {
 	KubeAPIBurst int
 
 	// Pull images one at a time.
-	SerializeImagePulls bool
+	SerializeImagePulls        bool
+	ExperimentalFlannelOverlay bool
 }
 
 // bootstrapping interface for kubelet, targets the initialization protocol
@@ -227,6 +231,7 @@ func NewKubeletServer() *KubeletServer {
 		ReconcileCIDR:                  true,
 		KubeAPIQPS:                     5.0,
 		KubeAPIBurst:                   10,
+		ExperimentalFlannelOverlay:     experimentalFlannelOverlay,
 	}
 }
 
@@ -341,6 +346,7 @@ func (s *KubeletServer) AddFlags(fs *pflag.FlagSet) {
 	fs.Float32Var(&s.KubeAPIQPS, "kube-api-qps", s.KubeAPIQPS, "QPS to use while talking with kubernetes apiserver")
 	fs.IntVar(&s.KubeAPIBurst, "kube-api-burst", s.KubeAPIBurst, "Burst to use while talking with kubernetes apiserver")
 	fs.BoolVar(&s.SerializeImagePulls, "serialize-image-pulls", s.SerializeImagePulls, "Pull images one at a time. We recommend *not* changing the default value on nodes that run docker daemon with version < 1.9 or an Aufs storage backend. Issue #10959 has more details. [default=true]")
+	fs.BoolVar(&s.ExperimentalFlannelOverlay, "experimental-flannel-overlay", s.ExperimentalFlannelOverlay, "Experimental support for starting the kubelet with the default overlay network (flannel). Assumes flanneld is already running in client mode. [default=false]")
 }
 
 // UnsecuredKubeletConfig returns a KubeletConfig suitable for being run, or an error if the server setup
@@ -478,6 +484,8 @@ func (s *KubeletServer) UnsecuredKubeletConfig() (*KubeletConfig, error) {
 		TLSOptions:                     tlsOptions,
 		Writer:                         writer,
 		VolumePlugins:                  ProbeVolumePlugins(),
+
+		ExperimentalFlannelOverlay: s.ExperimentalFlannelOverlay,
 	}, nil
 }
 
@@ -949,6 +957,8 @@ type KubeletConfig struct {
 	TLSOptions                     *kubelet.TLSOptions
 	Writer                         io.Writer
 	VolumePlugins                  []volume.VolumePlugin
+
+	ExperimentalFlannelOverlay bool
 }
 
 func CreateAndInitKubelet(kc *KubeletConfig) (k KubeletBootstrap, pc *config.PodConfig, err error) {
@@ -1031,6 +1041,7 @@ func CreateAndInitKubelet(kc *KubeletConfig) (k KubeletBootstrap, pc *config.Pod
 		kc.OOMAdjuster,
 		kc.SerializeImagePulls,
 		kc.ContainerManager,
+		kc.ExperimentalFlannelOverlay,
 	)
 
 	if err != nil {

docs/admin/kubelet.md

@@ -85,6 +85,7 @@ kubelet
       --enable-server[=true]: Enable the Kubelet's server
       --event-burst=10: Maximum size of a bursty event records, temporarily allows event records to burst to this number, while still not exceeding event-qps. Only used if --event-qps > 0
       --event-qps=5: If > 0, limit event creations per second to this value. If 0, unlimited.
+      --experimental-flannel-overlay[=false]: Experimental support for starting the kubelet with the default overlay network (flannel). Assumes flanneld is already running in client mode. [default=false]
       --file-check-frequency=20s: Duration between checking config files for new data
       --google-json-key="": The Google Cloud Platform Service Account JSON Key to use for authentication.
       --healthz-bind-address=127.0.0.1: The IP address for the healthz server to serve on, defaulting to 127.0.0.1 (set to 0.0.0.0 for all interfaces)
@@ -139,7 +140,7 @@ kubelet
       --tls-private-key-file="": File containing x509 private key matching --tls-cert-file.
 ```
 
-###### Auto generated by spf13/cobra on 21-Nov-2015
+###### Auto generated by spf13/cobra on 24-Nov-2015
 
 
 <!-- BEGIN MUNGE: GENERATED_ANALYTICS -->

docs/proposals/flannel-integration.md

+<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->
+
+<!-- BEGIN STRIP_FOR_RELEASE -->
+
+<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
+     width="25" height="25">
+<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
+     width="25" height="25">
+<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
+     width="25" height="25">
+<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
+     width="25" height="25">
+<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
+     width="25" height="25">
+
+<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
+
+If you are using a released version of Kubernetes, you should
+refer to the docs that go with that version.
+
+<strong>
+The latest release of this document can be found
+[here](http://releases.k8s.io/release-1.1/docs/proposals/flannel-integration.md).
+
+Documentation for other releases can be found at
+[releases.k8s.io](http://releases.k8s.io).
+</strong>
+--
+
+<!-- END STRIP_FOR_RELEASE -->
+
+<!-- END MUNGE: UNVERSIONED_WARNING -->
+
+# Flannel integration with Kubernetes
+
+## Why?
+
+* Networking works out of the box.
+* Cloud gateway configuration is regulated by quota.
+* Consistent bare metal and cloud experience.
+* Lays foundation for integrating with networking backends and vendors.
+
+## How?
+
+Thus:
+
+```
+Master                      |               Node1
+----------------------------------------------------------------------
+{192.168.0.0/16, 256 /24}   |               docker
+    |                       |                 | restart with podcidr
+apiserver            <------------------    kubelet (sends podcidr)
+    |                       |                 | here's podcidr, mtu
+flannel-server:10253 <------------------    flannel-daemon
+Allocates a /24      ------------------>    [config iptables, VXLan]
+                     <------------------    [watch subnet leases]
+I just allocated     ------------------>    [config VXLan]
+another /24                 |
+```
+
+## Proposal
+
+Explaining vxlan is out of the scope of this document, however it does take some basic understanding to grok the proposal. Assume some pod wants to communicate across nodes with the above setup. Check the flannel vxlan devices:
+
+```console
+node1 $ ip -d link show flannel.1
+4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1410 qdisc noqueue state UNKNOWN mode DEFAULT
+    link/ether a2:53:86:b5:5f:c1 brd ff:ff:ff:ff:ff:ff
+    vxlan
+node1 $ ip -d link show eth0
+2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc mq state UP mode DEFAULT qlen 1000
+    link/ether 42:01:0a:f0:00:04 brd ff:ff:ff:ff:ff:ff
+
+node2 $ ip -d link show flannel.1
+4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1410 qdisc noqueue state UNKNOWN mode DEFAULT
+    link/ether 56:71:35:66:4a:d8 brd ff:ff:ff:ff:ff:ff
+    vxlan
+node2 $ ip -d link show eth0
+2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc mq state UP mode DEFAULT qlen 1000
+    link/ether 42:01:0a:f0:00:03 brd ff:ff:ff:ff:ff:ff
+```
+
+Note that we're ignoring cbr0 for the sake of simplicity. Spin-up a container on each node. We're using raw docker for this example only because we want control over where the container lands:
+
+```
+node1 $ docker run -it radial/busyboxplus:curl /bin/sh
+[ root@5ca3c154cde3:/ ]$ ip addr show
+1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue
+8: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1410 qdisc noqueue
+    link/ether 02:42:12:10:20:03 brd ff:ff:ff:ff:ff:ff
+    inet 192.168.32.3/24 scope global eth0
+       valid_lft forever preferred_lft forever
+
+node2 $ docker run -it radial/busyboxplus:curl /bin/sh
+[ root@d8a879a29f5d:/ ]$ ip addr show
+1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue
+16: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1410 qdisc noqueue
+    link/ether 02:42:12:10:0e:07 brd ff:ff:ff:ff:ff:ff
+    inet 192.168.14.7/24 scope global eth0
+       valid_lft forever preferred_lft forever
+[ root@d8a879a29f5d:/ ]$ ping 192.168.32.3
+PING 192.168.32.3 (192.168.32.3): 56 data bytes
+64 bytes from 192.168.32.3: seq=0 ttl=62 time=1.190 ms
+```
+
+__What happened?__:
+
+From 1000 feet:
+* vxlan device driver starts up on node1 and creates a udp tunnel endpoint on 8472
+* container 192.168.32.3 pings 192.168.14.7
+    - what's the MAC of 192.168.14.0?
+        - L2 miss, flannel looks up MAC of subnet
+        - Stores `192.168.14.0 <-> 56:71:35:66:4a:d8` in neighbor table
+    - what's tunnel endpoint of this MAC?
+        - L3 miss, flannel looks up destination VM ip
+        - Stores `10.240.0.3 <-> 56:71:35:66:4a:d8` in bridge database
+* Sends `[56:71:35:66:4a:d8, 10.240.0.3][vxlan: port, vni][02:42:12:10:20:03, 192.168.14.7][icmp]`
+
+__But will it blend?__
+
+Kubernetes integration is fairly straight-forward once we understand the pieces involved, and can be prioritized as follows:
+* Kubelet understands flannel daemon in client mode, flannel server manages independent etcd store on master, node controller backs off cidr allocation
+* Flannel server consults the Kubernetes master for everything network related
+* Flannel daemon works through network plugins in a generic way without bothering the kubelet: needs CNI x Kubernetes standardization
+
+The first is accomplished in this PR, while a timeline for 2. and 3. are TDB. To implement the flannel api we can either run a proxy per node and get rid of the flannel server, or service all requests in the flannel server with something like a go-routine per node:
+* `/network/config`: read network configuration and return
+* `/network/leases`:
+	- Post:  Return a lease as understood by flannel
+		- Lookip node by IP
+		- Store node metadata from [flannel request] (https://github.com/coreos/flannel/blob/master/subnet/subnet.go#L34) in annotations
+		- Return [Lease object] (https://github.com/coreos/flannel/blob/master/subnet/subnet.go#L40) reflecting node cidr
+	- Get: Handle a watch on leases
+* `/network/leases/subnet`:
+	- Put: This is a request for a lease. If the nodecontroller is allocating CIDRs we can probably just no-op.
+* `/network/reservations`: TDB, we can probably use this to accomodate node controller allocating CIDR instead of flannel requesting it
+
+The ick-iest part of this implementation is going to the the `GET /network/leases`, i.e the watch proxy. We can side-step by waiting for a more generic Kubernetes resource. However, we can also implement it as follows:
+* Watch all nodes, ignore heartbeats
+* On each change, figure out the lease for the node, construct a [lease watch result](https://github.com/coreos/flannel/blob/0bf263826eab1707be5262703a8092c7d15e0be4/subnet/subnet.go#L72), and send it down the watch with the RV from the node
+* Implement a lease list that does a similar translation
+
+I say this is gross without an api objet because for each node->lease translation one has to store and retrieve the node metadata sent by flannel (eg: VTEP) from node annotations. [Reference implementation](https://github.com/bprashanth/kubernetes/blob/network_vxlan/pkg/kubelet/flannel_server.go) and [watch proxy](https://github.com/bprashanth/kubernetes/blob/network_vxlan/pkg/kubelet/watch_proxy.go).
+
+# Limitations
+
+* Integration is experimental
+* Flannel etcd not stored in persistent disk
+* CIDR allocation does *not* flow from Kubernetes down to nodes anymore
+
+# Wishlist
+
+This proposal is really just a call for community help in writing a Kubernetes x flannel backend.
+
+* CNI plugin integration
+* Flannel daemon in privileged pod
+* Flannel server talks to apiserver, described in proposal above
+* HTTPs between flannel daemon/server
+* Investigate flannel server runing on every node (as done in the reference implementation mentioned above)
+* Use flannel reservation mode to support node controller podcidr alloction
+
+
+<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/docs/proposals/flannel-integration.md?pixel)]()
+<!-- END MUNGE: GENERATED_ANALYTICS -->

hack/verify-flags/known-flags.txt

@@ -327,3 +327,4 @@ watch-only
 whitelist-override-label
 windows-line-endings
 www-prefix
+experimental-flannel-overlay

pkg/kubelet/flannel_helper.go

+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubelet
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+
+	utildbus "k8s.io/kubernetes/pkg/util/dbus"
+	utilexec "k8s.io/kubernetes/pkg/util/exec"
+	utiliptables "k8s.io/kubernetes/pkg/util/iptables"
+
+	"github.com/golang/glog"
+)
+
+// TODO: Move all this to a network plugin.
+const (
+	// TODO: The location of default docker options is distro specific, so this
+	// probably won't work on anything other than debian/ubuntu. This is a
+	// short-term compromise till we've moved overlay setup into a plugin.
+	dockerOptsFile    = "/etc/default/docker"
+	flannelSubnetKey  = "FLANNEL_SUBNET"
+	flannelNetworkKey = "FLANNEL_NETWORK"
+	flannelMtuKey     = "FLANNEL_MTU"
+	dockerOptsKey     = "DOCKER_OPTS"
+	flannelSubnetFile = "/var/run/flannel/subnet.env"
+)
+
+// A Kubelet to flannel bridging helper.
+type FlannelHelper struct {
+	subnetFile     string
+	iptablesHelper utiliptables.Interface
+}
+
+// NewFlannelHelper creates a new flannel helper.
+func NewFlannelHelper() *FlannelHelper {
+	return &FlannelHelper{
+		subnetFile:     flannelSubnetFile,
+		iptablesHelper: utiliptables.New(utilexec.New(), utildbus.New(), utiliptables.ProtocolIpv4),
+	}
+}
+
+// Ensure the required MASQUERADE rules exist for the given network/cidr.
+func (f *FlannelHelper) ensureFlannelMasqRule(kubeNetwork, podCIDR string) error {
+	// TODO: Investigate delegation to flannel via -ip-masq=true once flannel
+	// issue #374 is resolved.
+	comment := "Flannel masquerade facilitates pod<->node traffic."
+	args := []string{
+		"-m", "comment", "--comment", comment,
+		"!", "-d", kubeNetwork, "-s", podCIDR, "-j", "MASQUERADE",
+	}
+	_, err := f.iptablesHelper.EnsureRule(
+		utiliptables.Append,
+		utiliptables.TableNAT,
+		utiliptables.ChainPostrouting,
+		args...)
+	return err
+}
+
+// Handshake waits for the flannel subnet file and installs a few IPTables
+// rules, returning the pod CIDR allocated for this node.
+func (f *FlannelHelper) Handshake() (podCIDR string, err error) {
+	// TODO: Using a file to communicate is brittle
+	if _, err = os.Stat(f.subnetFile); err != nil {
+		return "", fmt.Errorf("Waiting for subnet file %v", f.subnetFile)
+	}
+	glog.Infof("Found flannel subnet file %v", f.subnetFile)
+
+	config, err := parseKVConfig(f.subnetFile)
+	if err != nil {
+		return "", err
+	}
+	if err = writeDockerOptsFromFlannelConfig(config); err != nil {
+		return "", err
+	}
+	podCIDR, ok := config[flannelSubnetKey]
+	if !ok {
+		return "", fmt.Errorf("No flannel subnet, config %+v", config)
+	}
+	kubeNetwork, ok := config[flannelNetworkKey]
+	if !ok {
+		return "", fmt.Errorf("No flannel network, config %+v", config)
+	}
+	if f.ensureFlannelMasqRule(kubeNetwork, podCIDR); err != nil {
+		return "", fmt.Errorf("Unable to install flannel masquerade %v", err)
+	}
+	return podCIDR, nil
+}
+
+// Take env variables from flannel subnet env and write to /etc/docker/defaults.
+func writeDockerOptsFromFlannelConfig(flannelConfig map[string]string) error {
+	// TODO: Write dockeropts to unit file on systemd machines
+	// https://github.com/docker/docker/issues/9889
+	mtu, ok := flannelConfig[flannelMtuKey]
+	if !ok {
+		return fmt.Errorf("No flannel mtu, flannel config %+v", flannelConfig)
+	}
+	dockerOpts, err := parseKVConfig(dockerOptsFile)
+	if err != nil {
+		return err
+	}
+	opts, ok := dockerOpts[dockerOptsKey]
+	if !ok {
+		glog.Errorf("Did not find docker opts, writing them")
+		opts = fmt.Sprintf(
+			" --bridge=cbr0 --iptables=false --ip-masq=false")
+	} else {
+		opts, _ = strconv.Unquote(opts)
+	}
+	dockerOpts[dockerOptsKey] = fmt.Sprintf("\"%v --mtu=%v\"", opts, mtu)
+	if err = writeKVConfig(dockerOptsFile, dockerOpts); err != nil {
+		return err
+	}
+	return nil
+}
+
+// parseKVConfig takes a file with key-value env variables and returns a dictionary mapping the same.
+func parseKVConfig(filename string) (map[string]string, error) {
+	config := map[string]string{}
+	if _, err := os.Stat(filename); err != nil {
+		return config, err
+	}
+	buff, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return config, err
+	}
+	str := string(buff)
+	glog.Infof("Read kv options %+v from %v", str, filename)
+	for _, line := range strings.Split(str, "\n") {
+		kv := strings.Split(line, "=")
+		if len(kv) != 2 {
+			glog.Warningf("Ignoring non key-value pair %v", kv)
+			continue
+		}
+		config[string(kv[0])] = string(kv[1])
+	}
+	return config, nil
+}
+
+// writeKVConfig writes a kv map as env variables into the given file.
+func writeKVConfig(filename string, kv map[string]string) error {
+	if _, err := os.Stat(filename); err != nil {
+		return err
+	}
+	content := ""
+	for k, v := range kv {
+		content += fmt.Sprintf("%v=%v\n", k, v)
+	}
+	glog.Warningf("Writing kv options %+v to %v", content, filename)
+	return ioutil.WriteFile(filename, []byte(content), 0644)
+}

pkg/kubelet/kubelet.go

@@ -217,6 +217,7 @@ func NewMainKubelet(
 	oomAdjuster *oom.OOMAdjuster,
 	serializeImagePulls bool,
 	containerManager cm.ContainerManager,
+	flannelExperimentalOverlay bool,
 ) (*Kubelet, error) {
 
 	if rootDirectory == "" {
@@ -327,8 +328,20 @@ func NewMainKubelet(
 		cpuCFSQuota:                    cpuCFSQuota,
 		daemonEndpoints:                daemonEndpoints,
 		containerManager:               containerManager,
+		flannelExperimentalOverlay:     flannelExperimentalOverlay,
+		flannelHelper:                  NewFlannelHelper(),
+	}
+	if klet.flannelExperimentalOverlay {
+		glog.Infof("Flannel is in charge of podCIDR and overlay networking.")
+	}
+	if klet.kubeClient == nil {
+		// The master kubelet cannot wait for the flannel daemon because it is responsible
+		// for starting up the flannel server in a static pod. So even though the flannel
+		// daemon runs on the master, it doesn't hold up cluster bootstrap. All the pods
+		// on the master run with host networking, so the master flannel doesn't care
+		// even if the network changes. We only need it for the master proxy.
+		klet.flannelExperimentalOverlay = false
 	}
-
 	if plug, err := network.InitNetworkPlugin(networkPlugins, networkPluginName, &networkHost{klet}); err != nil {
 		return nil, err
 	} else {
@@ -649,6 +662,13 @@ type Kubelet struct {
 
 	// oneTimeInitializer is used to initialize modules that are dependent on the runtime to be up.
 	oneTimeInitializer sync.Once
+
+	flannelExperimentalOverlay bool
+
+	// TODO: Flannelhelper doesn't store any state, we can instantiate it
+	// on the fly if we're confident the dbus connetions it opens doesn't
+	// put the system under duress.
+	flannelHelper *FlannelHelper
 }
 
 func (kl *Kubelet) allSourcesReady() bool {
@@ -2619,6 +2639,16 @@ var oldNodeUnschedulable bool
 func (kl *Kubelet) syncNetworkStatus() {
 	var err error
 	if kl.configureCBR0 {
+		if kl.flannelExperimentalOverlay {
+			podCIDR, err := kl.flannelHelper.Handshake()
+			if err != nil {
+				glog.Infof("Flannel server handshake failed %v", err)
+				return
+			}
+			glog.Infof("Setting cidr: %v -> %v",
+				kl.runtimeState.podCIDR(), podCIDR)
+			kl.runtimeState.setPodCIDR(podCIDR)
+		}
 		if err := ensureIPTablesMasqRule(); err != nil {
 			err = fmt.Errorf("Error on adding ip table rules: %v", err)
 			glog.Error(err)
@@ -2884,7 +2914,22 @@ func (kl *Kubelet) tryUpdateNodeStatus() error {
 	if node == nil {
 		return fmt.Errorf("no node instance returned for %q", kl.nodeName)
 	}
-	if kl.reconcileCIDR {
+	// Flannel is the authoritative source of pod CIDR, if it's running.
+	// This is a short term compromise till we get flannel working in
+	// reservation mode.
+	if kl.flannelExperimentalOverlay {
+		flannelPodCIDR := kl.runtimeState.podCIDR()
+		if node.Spec.PodCIDR != flannelPodCIDR {
+			node.Spec.PodCIDR = flannelPodCIDR
+			glog.Infof("Updating podcidr to %v", node.Spec.PodCIDR)
+			if updatedNode, err := kl.kubeClient.Nodes().Update(node); err != nil {
+				glog.Warningf("Failed to update podCIDR: %v", err)
+			} else {
+				// Update the node resourceVersion so the status update doesn't fail.
+				node = updatedNode
+			}
+		}
+	} else if kl.reconcileCIDR {
 		kl.runtimeState.setPodCIDR(node.Spec.PodCIDR)
 	}
 

pkg/master/ports/ports.go

@@ -32,6 +32,8 @@ const (
 	// ControllerManagerPort is the default port for the controller manager status server.
 	// May be overridden by a flag at startup.
 	ControllerManagerPort = 10252
+	// Port for flannel daemon.
+	FlannelDaemonPort = 10253
 	// KubeletReadOnlyPort exposes basic read-only services from the kubelet.
 	// May be overridden by a flag at startup.
 	// This is necessary for heapster to collect monitoring stats from the kubelet