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Added clustered etcd example

Michal Fojtik authored on 2015/05/06 23:31:39
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examples/etcd/Dockerfile
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+FROM centos:centos7
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+MAINTAINER http://openshift.io
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+
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+RUN yum install -y tar bind-utils && yum clean all
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+
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+ENV ETCD_RELEASE v2.0.10
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+
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+LABEL k8s.io/description="A highly-available key-value store for shared configuration and service discovery" \
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+      k8s.io/display-name="etcd v2.0.10" \
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+      openshift.io/expose-services="2379:http,2380:etcd" \
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+      openshift.io/tags="database,etcd,etcd20"
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+
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+RUN ETCD_URL=https://github.com/coreos/etcd/releases/download/${ETCD_RELEASE}/etcd-${ETCD_RELEASE}-linux-amd64.tar.gz && \
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+  mkdir -p /tmp/etcd && cd /tmp/etcd && \
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+  curl -L ${ETCD_URL} | tar -xzf - --strip-components=1 && \
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+  mv {etcd,etcdctl} /usr/local/bin/ && \
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+  mkdir -p /var/lib/etcd && \
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+  rm -rf /tmp/etcd
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+
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+EXPOSE 2379 2380
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+
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+VOLUME ["/var/lib/etcd"]
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+
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+ADD etcd*.sh /usr/local/bin/
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+
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+CMD ["/usr/local/bin/etcd.sh"]
examples/etcd/Makefile
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+all:
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+	docker build -t openshift/etcd-20-centos7 .
examples/etcd/README.md
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+Clustered etcd Template
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+========================
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+
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+etcd is a distributed, consistent key value store for shared configuration and
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+service discovery. For more details about etcd, visit:
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+
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+https://github.com/coreos/etcd
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+
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+### Requirements
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+
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+You can 'pre-pull' the Docker image used by this template by:
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+
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+```
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+$ docker pull openshift/etcd-20-centos7
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+```
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+
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+You can also build this Docker image yourself, by using provided Makefile:
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+
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+```
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+$ make
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+```
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+
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+### How to use this template
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+
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+You can import this template to OpenShift using:
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+
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+```
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+$ osc create -f examples/etcd/template.json
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+```
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+
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+Then you can navigate to OpenShift UI and click the 'Create' button on top right
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+and choose 'Browse templates...'. Choose the 'etcd' and hit create.
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+
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+Another way, is to use the CLI only:
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+
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+```
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+$ osc process -f examples/etcd/template.json | osc create -f -
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+```
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+
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+### How does it work
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+
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+This template creates two Services. The first service is used for initial
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+discovery and stores information about running members. This service is used
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+only internally by the cluster members and you should not need to access it.
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+You can however obtain information about the current state/size of the cluster.
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+
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+The second service 'etcd' is the main entrypoint for accessing the 'etcd'
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+cluster. This service is exposing two ports. The port 2380 is used for internal
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+server-to-server communication and the port 2379 is used for the client
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+connections.
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+
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+The 'etcd-discovery' pod created by this template will create an instance of
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+etcd server, that is used as cluster discovery service. This pod can be stopped
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+or deleted when desired size of the cluster is reached. If you want to add more
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+members you will have to start this pod again manually.
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+
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+The 'etcd' replication controller manage creation of the etcd cluster members.
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+By default this template will start 3 members. The members then register
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+themselves using the discovery service and elect the leader. You can adjust the
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+number of replicas as long as the 'etcd-discovery' service is running.
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+
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+### Cleaning up
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+
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+If you're done playing, you can remove all the created resources by executing
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+following command:
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+
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+```
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+$ ./examples/etcd/teardown.sh
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+```
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+
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+Note: This will also remove all data you have stored in the etcd.
examples/etcd/etcd-discovery.sh
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+#!/bin/bash -e
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+#
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+# This is a wrapper for the etcd that serves as 'discovery' server and manager
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+# for the cluster configuration
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+
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+address=$(getent ahosts ${HOSTNAME} | grep RAW | cut -d ' ' -f 1)
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+
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+exec /usr/local/bin/etcd \
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+  -advertise-client-urls http://${address}:2379 \
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+  -listen-client-urls http://${address}:2379 \
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+  -data-dir /var/lib/etcd \
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+  -name discovery
examples/etcd/etcd.sh
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+#!/bin/bash
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+#
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+# This is a wrapper script for the etcd command.
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+# This wrapper detects the presence of ETCD_DISCOVERY environment variable and
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+# if this variable is set then it will use DNS lookup to collect the IP
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+# addresses of the other members of the cluster. This wrapper then adjust the
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+# size of the cluster in the discovery service and register itself.
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+
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+# If we are not running in cluster, then just execute the etcd binary
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+if [[ -z "${ETCD_DISCOVERY-}" ]]; then
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+  exec /usr/local/bin/etcd "$@"
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+fi
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+
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+address=$(getent ahosts ${HOSTNAME} | grep RAW | cut -d ' ' -f 1)
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+
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+curl -sX PUT ${ETCD_DISCOVERY}/_config/size -d value=${ETCD_NUM_MEMBERS}
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+
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+# Adding UNIX timestamp prevents having duplicate member id's
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+member_id="${HOSTNAME}-$(date +"%s")"
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+
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+echo "Starting member ${member_id} (${address})..."
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+exec /usr/local/bin/etcd \
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+  -initial-advertise-peer-urls http://${address}:2380 \
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+  -listen-peer-urls http://${address}:2380 \
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+  -advertise-client-urls http://${address}:2379 \
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+  -listen-client-urls http://${address}:2379 \
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+  -data-dir /var/lib/etcd \
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+  -name ${member_id}
examples/etcd/template.json
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+{
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+  "kind": "Template",
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+  "apiVersion": "v1beta1",
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+  "labels": {
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+    "template": "etcd"
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+  },
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+  "metadata": {
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+    "annotations": {
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+      "description": "Example of clustered etcd",
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+      "tags": "database,etcd",
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+      "iconClass" : "icon-database"
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+    },
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+    "name": "etcd"
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+  },
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+  "parameters": [
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+    {
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+      "name": "ETCD_IMAGE",
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+      "description": "The name of etcd Docker image to use",
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+      "value": "openshift/etcd-20-centos7"
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+    },
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+    {
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+      "name": "ETCD_NUM_MEMBERS",
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+      "description": "Maximum number of members to launch (have to match with # of replicas)",
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+      "value": "3"
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+    },
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+    {
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+      "name": "ETCD_DISCOVERY",
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+      "description": "A token used for etcd discovery",
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+      "from": "http://etcd-discovery:2379/v2/keys/discovery/[a-z0-9]{40}",
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+      "generate": "expression"
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+    },
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+    {
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+      "name": "ETCD_CLUSTER_TOKEN",
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+      "description": "A token etcd use to generate unique cluster ID and member ID",
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+      "from": "etcd-cluster-[a-z0-9]{5}",
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+      "generate": "expression"
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+    }
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+  ],
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+  "items":[
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+    {
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+      "apiVersion": "v1beta1",
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+      "kind": "ImageStream",
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+      "metadata": {
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+        "name": "etcd"
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+      },
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+      "spec": {
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+        "dockerImageRepository": "${ETCD_IMAGE}",
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+        "tags": [
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+          {
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+            "name": "latest",
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+            "annotations": {
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+              "description": "Provides etcd v2.0.10",
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+              "iconClass": "icon-database",
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+              "tags": "database,etcd",
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+              "version": "2.0.10"
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+            }
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+          }
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+        ]
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+      }
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+    },
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+    {
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+      "kind": "Service",
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+      "apiVersion": "v1beta3",
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+      "metadata": {
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+        "name": "etcd-discovery",
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+        "labels": {
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+          "name": "etcd-discovery"
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+        }
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+      },
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+      "spec": {
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+        "portalIp": "None",
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+        "ports": [
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+          {
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+            "port": 2379,
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+            "targetPort": 2379
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+          }
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+        ],
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+        "selector": {
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+          "name": "etcd-discovery"
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+        }
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+      }
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+    },
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+    {
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+      "kind": "Service",
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+      "apiVersion": "v1beta3",
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+      "metadata": {
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+        "name": "etcd",
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+        "labels": {
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+          "name": "etcd"
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+        }
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+      },
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+      "spec": {
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+        "portalIP": "None",
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+        "ports": [
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+          {
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+            "name": "client",
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+            "port": 2379,
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+            "targetPort": 2379
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+          },
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+          {
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+            "name": "server",
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+            "port": 2380,
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+            "targetPort": 2380
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+          }
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+        ],
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+        "selector": {
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+          "name": "etcd"
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+        }
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+      }
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+    },
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+    {
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+      "apiVersion": "v1beta1",
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+      "kind": "DeploymentConfig",
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+      "metadata": {
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+        "name": "etcd-discovery"
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+      },
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+      "template": {
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+        "controllerTemplate": {
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+          "podTemplate": {
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+            "desiredState": {
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+              "manifest": {
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+                "containers":[
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+                  {
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+                    "name":  "discovery",
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+                    "image": "${ETCD_IMAGE}",
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+                    "command": ["etcd-discovery.sh"],
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+                    "ports":[
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+                      {
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+                        "containerPort": 2379
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+                      }
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+                    ]
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+                  }
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+                ],
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+                "version": "v1beta1"
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+              }
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+            },
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+            "labels": {
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+              "name": "etcd-discovery"
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+            }
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+          },
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+          "replicaSelector": {
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+            "name": "etcd-discovery"
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+          },
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+          "replicas": 1
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+        },
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+        "strategy": {
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+          "type": "Recreate"
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+        }
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+      },
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+      "triggers": [
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+        {
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+          "type": "ConfigChange"
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+        }
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+      ]
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+    },
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+    {
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+      "apiVersion": "v1beta1",
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+      "kind": "DeploymentConfig",
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+      "metadata": {
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+        "name": "etcd"
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+      },
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+      "template": {
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+        "controllerTemplate": {
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+          "podTemplate": {
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+            "desiredState": {
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+              "manifest": {
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+                "containers":[
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+                  {
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+                    "name":  "member",
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+                    "image": "${ETCD_IMAGE}",
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+                    "env": [
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+                      {
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+                        "name": "ETCD_NUM_MEMBERS",
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+                        "value": "${ETCD_NUM_MEMBERS}"
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+                      },
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+                      {
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+                        "name": "ETCD_INITIAL_CLUSTER_STATE",
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+                        "value": "new"
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+                      },
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+                      {
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+                        "name": "ETCD_INITIAL_CLUSTER_TOKEN",
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+                        "value": "${ETCD_CLUSTER_TOKEN}"
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+                      },
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+                      {
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+                        "name": "ETCD_DISCOVERY",
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+                        "value": "${ETCD_DISCOVERY}"
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+                      }
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+                    ],
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+                    "ports":[
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+                      {
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+                        "containerPort": 2379
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+                      },
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+                      {
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+                        "containerPort": 2380
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+                      }
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+                    ]
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+                  }
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+                ],
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+                "version": "v1beta1"
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+              }
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+            },
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+            "labels": {
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+              "name": "etcd"
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+            }
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+          },
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+          "replicaSelector": {
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+            "name": "etcd"
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+          },
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+          "replicas": 3
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+        },
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+        "strategy": {
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+          "type": "Recreate"
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+        }
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+      },
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+      "triggers": [
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+        {
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+          "type": "ConfigChange"
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+        }
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+      ]
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+    }
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+  ]
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+}