Add an example for running rethinkdb cluster on k8s

examples/rethinkdb/README.md

+RethinkDB Cluster on Kubernetes
+==============================
+
+Setting up a [rethinkdb](http://rethinkdb.com/) cluster on [kubernetes](http://kubernetes.io)
+
+**Features**
+
+ * Auto configuration cluster by querying info from k8s
+ * Simple
+
+Quick start
+-----------
+
+**Step 1**
+
+antmanler/rethinkdb will discover peer using endpoints porvided by kubernetes_ro service,
+so firstly create a service so the following pod can query its endpoint
+
+```shell
+kubectl create -f driver-service.yaml
+```
+
+check out:
+
+```shell
+$kubectl get se
+NAME                LABELS              SELECTOR                  IP                  PORT
+rethinkdb-driver    db=influxdb         db=rethinkdb              10.241.105.47       28015
+```
+
+**Step 2**
+
+start fist server in cluster
+
+```shell
+kubectl create -f rc.yaml
+```
+
+Actually, you can start servers as many as you want at one time, just modify the `replicas` in `rc.ymal`
+
+check out again:
+
+```shell
+$kubectl get po
+POD                                    IP                  CONTAINER(S)        IMAGE(S)            HOST                LABELS                       STATUS
+99f6d361-abd6-11e4-a1ea-001c426dbc28   10.240.2.68         rethinkdb           rethinkdb:1.16.0    10.245.2.2/         db=rethinkdb,role=replicas   Running
+```
+
+**Done!**
+
+
+---
+
+Scale
+-----
+
+You can scale up you cluster using `kubectl resize`, and new pod will join to exsits cluster automatically, for example
+
+
+```shell
+$kubectl resize rc rethinkdb-rc-1.16.0 --replicas=3
+resized
+$kubectl get po
+POD                                    IP                  CONTAINER(S)        IMAGE(S)            HOST                LABELS                       STATUS
+99f6d361-abd6-11e4-a1ea-001c426dbc28   10.240.2.68         rethinkdb           rethinkdb:1.16.0    10.245.2.2/         db=rethinkdb,role=replicas   Running
+d10182b5-abd6-11e4-a1ea-001c426dbc28   10.240.26.14        rethinkdb           rethinkdb:1.16.0    10.245.2.4/         db=rethinkdb,role=replicas   Running
+d101c1a4-abd6-11e4-a1ea-001c426dbc28   10.240.11.14        rethinkdb           rethinkdb:1.16.0    10.245.2.3/         db=rethinkdb,role=replicas   Running
+```
+
+Admin
+-----
+
+You need a separate pod (which labled as role:admin) to access Web Admin UI
+
+```shell
+kubectl create -f admin-pod.yaml
+kubectl create -f admin-service.yaml
+```
+
+find the service
+
+```shell
+$kubectl get se
+NAME                LABELS              SELECTOR                  IP                  PORT
+rethinkdb-admin     db=influxdb         db=rethinkdb,role=admin   10.241.220.209      8080
+rethinkdb-driver    db=influxdb         db=rethinkdb              10.241.105.47       28015
+```
+
+open a web browser and access to *http://10.241.220.209:8080* to manage you cluster
+
+**Why not just using pods in replicas?**
+
+This is because kube-proxy will act as a load balancer and send your traffic to different server,
+since the ui is not stateless when playing with Web Admin UI will cause `Connection not open on server` error.
+
+
+- - -
+
+**BTW**
+
+  * All services and pods are placed under namespace `rethinkdb`.
+
+  * `gen_pod.sh` is using to generate pod templates for my local cluster,
+the generated pods which is using `nodeSelector` to force k8s to schedule containers to my designate nodes, for I need to access persistent data on my host dirs.
+
+  * see [antmanler/rethinkdb-k8s](https://github.com/antmanler/rethinkdb-k8s) for detail

examples/rethinkdb/admin-pod.yaml

+apiVersion: v1beta1
+namespace: rethinkdb
+kind: Pod
+id: rethinkdb-admin-1.16.0
+labels:
+  db: rethinkdb
+  role: admin
+desiredState:
+  manifest:
+    version: v1beta1
+    id: rethinkdb
+    containers:
+      - name: rethinkdb
+        image: antmanler/rethinkdb:1.16.0
+        ports:
+          - name: admin-port
+            containerPort: 8080
+          - name: driver-port
+            containerPort: 28015
+          - name: cluster-port
+            containerPort: 29015
+        volumeMounts:
+          - name: rethinkdb-storage
+            mountPath: /data/rethinkdb_data
+    volumes:
+      - name: rethinkdb-storage
+        source:
+          emptyDir: {}
+    restartPolicy:
+      always: {}

examples/rethinkdb/admin-service.yaml

+apiVersion: v1beta1
+namespace: rethinkdb
+kind: Service
+id: rethinkdb-admin
+containerPort: admin-port
+port: 8080
+labels:
+  db: influxdb
+selector:
+  db: rethinkdb
+  role: admin

examples/rethinkdb/driver-service.yaml

+apiVersion: v1beta1
+namespace: rethinkdb
+kind: Service
+id: rethinkdb-driver
+containerPort: driver-port
+port: 28015
+labels:
+  db: influxdb
+selector:
+  db: rethinkdb

examples/rethinkdb/gen-pod.sh

+#!/bin/bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+: ${VERSION:=1.16.0}
+
+readonly NAME=${1-}
+if [[ -z "${NAME}" ]]; then
+  echo -e "\033[1;31mName must be specified\033[0m"
+  exit 1
+fi
+
+ADMIN=""
+if [[ ${NAME} == "admin" ]]; then
+  ADMIN="role: admin"
+fi
+
+NODE=""
+if [[ ! -z "${2-}" ]]; then
+  NODE="nodeSelector: { name: ${2} }"
+fi
+
+cat << EOF
+apiVersion: v1beta1
+namespace: rethinkdb
+kind: Pod
+id: rethinkdb-${NAME}-${VERSION}
+${NODE}
+labels:
+  db: rethinkdb
+  ${ADMIN}
+desiredState:
+  manifest:
+    version: v1beta1
+    id: rethinkdb
+    containers:
+      - name: rethinkdb
+        image: antmanler/rethinkdb:${VERSION}
+        ports:
+          - name: admin-port
+            containerPort: 8080
+          - name: driver-port
+            containerPort: 28015
+          - name: cluster-port
+            containerPort: 29015
+        volumeMounts:
+          - name: rethinkdb-storage
+            mountPath: /data/rethinkdb_data
+    volumes:
+      - name: rethinkdb-storage
+        source:
+          hostDir:
+            path: /data/db/rethinkdb
+    restartPolicy:
+      always: {}
+EOF

examples/rethinkdb/image/Dockerfile

+FROM rethinkdb:1.16.0
+
+MAINTAINER BinZhao <wo@zhaob.in>
+
+RUN apt-get update && \
+    apt-get install -yq curl && \
+    rm -rf /var/cache/apt/* && rm -rf /var/lib/apt/lists/* && \
+    curl -L http://stedolan.github.io/jq/download/linux64/jq > /usr/bin/jq && \
+    chmod u+x /usr/bin/jq
+
+COPY ./run.sh /usr/bin/run.sh
+RUN chmod u+x /usr/bin/run.sh
+
+CMD ["/usr/bin/run.sh"]

examples/rethinkdb/image/run.sh

+#!/bin/bash
+
+set -o pipefail
+
+IP=""
+if [[ -n "${KUBERNETES_RO_SERVICE_HOST}" ]]; then
+
+  : ${NAMESPACE:=rethinkdb}
+  # try to pick up first different ip from endpoints
+  MYHOST=$(ip addr | grep 'state UP' -A2 | tail -n1 | awk '{print $2}' | cut -f1  -d'/')
+  URL="${KUBERNETES_RO_SERVICE_HOST}/api/v1beta1/endpoints/rethinkdb-driver?namespace=${NAMESPACE}"
+  IP=$(curl -s ${URL} | jq -s -r --arg h "${MYHOST}" '.[0].endpoints | [ .[]? | split(":") ] | map(select(.[0] != $h)) | .[0][0]') || exit 1
+  [[ "${IP}" == null ]] && IP=""
+fi
+
+if [[ -n "${IP}" ]]; then
+  ENDPOINT="${IP}:29015"
+  echo "Join to ${ENDPOINT}"
+  exec rethinkdb --bind all  --join ${ENDPOINT}
+else
+  echo "Start single instance"
+  exec rethinkdb --bind all
+fi

examples/rethinkdb/rc.yaml

+apiVersion: v1beta1
+namespace: rethinkdb
+kind: ReplicationController
+id: rethinkdb-rc-1.16.0
+labels:
+  db: rethinkdb
+desiredState:
+  replicas: 1
+  replicaSelector:
+    db: rethinkdb
+    role: replicas
+  podTemplate:
+    labels:
+      db: rethinkdb
+      role: replicas
+    desiredState:
+      manifest:
+        version: v1beta1
+        id: rethinkdb
+        containers:
+          - name: rethinkdb
+            image: antmanler/rethinkdb:1.16.0
+            ports:
+              - name: admin-port
+                containerPort: 8080
+              - name: driver-port
+                containerPort: 28015
+              - name: cluster-port
+                containerPort: 29015
+            volumeMounts:
+                - name: rethinkdb-storage
+                  mountPath: /data/rethinkdb_data
+        volumes:
+          - name: rethinkdb-storage
+            source:
+              emptyDir: {}