elasticsearch-downgrade-semaphore.sh

#!/bin/bash

###
# Script for downgrading Elasticsearch to version 1.3.9
#
# Before running this script, please reset your dependency cache in Project Settings > Admin.
#
# Add the line below to your Setup commands in Project Settings (without the # at the beginning):
#
# wget https://gist.githubusercontent.com/reggieb/c16ce698f482904ad0a8f81bd1fe7af4/raw/1fc5a9883ee85f74b6fc8415213deac69b002e55/elasticsearch-downgrade-semaphore.sh ; sudo bash elasticsearch-downgrade-semaphore.sh
#
###

ES_HOST="0.0.0.0"
ES_PORT="9200"
ES_VERSION=${1:-'1.3.9'}
DEB="elasticsearch-$ES_VERSION.deb"
URL="https://download.elastic.co/elasticsearch/elasticsearch/$DEB"

function wait_for_elasticsearch() {
  printf "Waiting for ElasticSearch to become available"

  while true; do
    printf "."

    nc -4 -w 5 $ES_HOST $ES_PORT 2>/dev/null && break
    sleep 1
  done
  
  printf "\n"
}

function setup_java() {
  source /opt/change-java-version.sh
  change-java-version 7
}

function remove_installed_version() {
  echo "Stopping the service, removing current Elasticsearch and its configuration..."

  service elasticsearch stop
  sleep 1
  apt-get purge -y elasticsearch
  rm -rf /var/lib/elasticsearch
}

function install_version() {
  if ! [ -e $SEMAPHORE_CACHE_DIR/$DEB ]; then
    echo "Downloading Elasticsearch $ES_VERSION..."
    wget -O $SEMAPHORE_CACHE_DIR/$DEB $URL
  fi

  echo "Installing Elasticsearch $ES_VERSION..."
  echo 'Y' | dpkg -i $SEMAPHORE_CACHE_DIR/$DEB

  echo "Configuring Elasticsearch..."

  # Set the service to start on all runlevels
  update-rc.d elasticsearch defaults 95 10
  service elasticsearch stop

  # Default configuration for this version of Elasticsearch
  # It may not work with latest versions, be careful
  echo 'index.number_of_shards: 1' >> /etc/elasticsearch/elasticsearch.yml
  echo 'index.number_of_replicas: 0' >> /etc/elasticsearch/elasticsearch.yml
  service elasticsearch start

  echo "Installation completed successfully."
}

function run_health_check() {
  echo "Running health check..."
  curl http://"$ES_HOST":"$ES_PORT"/_cluster/health?pretty=true
}

if [ $EUID != 0 ]; then echo 'This script must be run as root, or by using sudo.'; exit 1; fi

setup_java

remove_installed_version

install_version

wait_for_elasticsearch

run_health_check

echo "Downgrade complete. Elasticsearch status:"
curl 'http://0.0.0.0:9200/?pretty'