storage: add etcd storage

This patch adds etcd storage implementation. This should be useful in
environments where
- we dont want to depends on a separate, hard to maintain SQL cluster
- we dont want to incur the overhead of talking to kubernetes apiservers
- kubernetes is not available yet, or if kubernetes depends on dex
to perform authentication and the operator would like to remove any
circular dependency if possible.

storage/etcd/standup.sh

@@ -0,0 +1,109 @@
+#!/bin/bash
+
+if [ "$EUID" -ne 0 ]
+  then echo "Please run as root"
+  exit
+fi
+
+function usage {
+  cat << EOF >> /dev/stderr
+Usage: sudo ./standup.sh [create|destroy] [etcd]
+
+This is a script for standing up test databases. It uses systemd to daemonize
+rkt containers running on a local loopback IP.
+
+The general workflow is to create a daemonized container, use the output to set
+the test environment variables, run the tests, then destroy the container.
+
+	sudo ./standup.sh create etcd
+	# Copy environment variables and run tests.
+	go test -v -i # always install test dependencies
+	go test -v
+	sudo ./standup.sh destroy etcd
+
+EOF
+  exit 2
+}
+
+function main {
+  if [ "$#" -ne 2 ]; then
+    usage
+    exit 2
+  fi
+
+  case "$1" in
+  "create")
+     case "$2" in
+     "etcd")
+        create_etcd;;
+     *)
+       usage
+       exit 2
+       ;;
+     esac
+     ;;
+  "destroy")
+     case "$2" in
+     "etcd")
+        destroy_etcd;;
+     *)
+       usage
+       exit 2
+       ;;
+     esac
+     ;;
+  *)
+    usage
+    exit 2
+    ;;
+  esac
+}
+
+function wait_for_file {
+  while [ ! -f $1 ]; do
+    sleep 1
+  done
+}
+
+function wait_for_container {
+  while [ -z "$( rkt list --full | grep $1 | grep running )" ]; do
+    sleep 1
+  done
+}
+
+function create_etcd {
+  UUID_FILE=/tmp/dex-etcd-uuid
+  if [ -f $UUID_FILE ]; then
+    echo "etcd database already exists, try ./standup.sh destroy etcd"
+    exit 2
+  fi
+
+  echo "Starting etcd . To view progress run:"
+  echo ""
+  echo "  journalctl -fu dex-etcd"
+  echo ""
+  UNIFIED_CGROUP_HIERARCHY=no \
+  systemd-run --unit=dex-etcd \
+      rkt run --uuid-file-save=$UUID_FILE --insecure-options=image \
+	  --net=host \
+	  docker://quay.io/coreos/etcd:v3.2.9
+
+  wait_for_file $UUID_FILE
+
+  UUID=$( cat $UUID_FILE )
+  wait_for_container $UUID
+  echo "To run tests export the following environment variables:"
+  echo ""
+  echo "  export DEX_ETCD_ENDPOINTS=http://localhost:2379"
+  echo ""
+}
+
+function destroy_etcd {
+  UUID_FILE=/tmp/dex-etcd-uuid
+  systemctl stop dex-etcd
+  rkt rm --uuid-file=$UUID_FILE
+  rm $UUID_FILE
+}
+
+
+main $@