Module: ElasticUtil

Defined in:
lib/elastic_util.rb

Overview

This module provides a way to backup and restore elasticsearch data.

Examples:

Backup data from one elasticsearch cluster and restore it to another.


ElasticUtil.backup('http://localhost:9200', '/tmp/mybackup', {size:5000})
ElasticUtil.restore('http://localhost:9201', '/tmp/mybackup')

Defined Under Namespace

Classes: Error

Constant Summary collapse

VERSION = 
"0.1.5"
DUMP_DIR =

The name of the data directory, relative to the user provided backup directory.

"es_data"

Class Method Summary collapse

Class Method Details

.backup(url, backup_dir, opts = {}) ⇒ true

Backup elasticsearch data to a local directory.

This uses ElasticSearch’s scroll api to fetch all records for indices and write the data to a local directory. The files it generates are given a .json.data extension. They are not valid JSON files, but rather are in the format expected by ElasticSearch’s _bulk api.

So #restore simply has to POST the contents of each file.

Use the :size option to change the number or results to fetch at once, and also the size of the data files generated. The latter correlates to the of the the api requests made in #restore.

Examples:

Backup default elasticsearch running locally.


ElasticUtil.backup('http://localhost:9200', '/tmp/mybackup')

Parameters:

  • url (String) —

    The url of the elasticsearch cluster eg. ‘localhost:9200’

  • backup_dir (String) —

    The local directory to store data in. eg. ‘/tmp/es2.4’

  • opts (Hash) (defaults to: {}) —

    The options for this backup.

Options Hash (opts):

  • :indices (Array) —

    The indices to backup. Default is all.

  • :exclude_indices (Array) —

    Exclude certain indexes.

  • :exclude_fields (Array) —

    Exclude certain fields. Default is [‘_id’].

  • :scroll (String) —

    The scroll api parameter, Default is ‘5m’.

  • :size (Integer) —

    The size api parameter. Default is 1000.

  • :force (true) —

    Delete existing backup directory instead of erroring. Default is false.

  • :quiet (true) —

    Don’t print anything. Default is false.

Returns:

  • (true) —

    or raises an error



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# File 'lib/elastic_util.rb', line 53

def self.backup(url, backup_dir, opts={})
  start_time = Time.now
  backup_dir = backup_dir.strip
  path = File.join(backup_dir.strip, DUMP_DIR)
  indices = []
  
  # ping it first
  uri = URI(url)
  response = Net::HTTP.get_response(uri)
  http = Net::HTTP.new(uri.host, uri.port)
  http.read_timeout = (60*3)
  http.open_timeout = 5
  response = http.start() {|http|
    http.get("/")
  }
  if !response.is_a?(Net::HTTPSuccess)
    raise Error, "Unable to reach elasticsearch at url '#{url}'!\n#{response.inspect}\n#{response.body.to_s}"
  end

  # determine indices to backup, default is everything.
  if opts[:indices]
    indices = opts[:indices]
  else
    uri = URI(url + "/_cat/indices?format=json")
    response = Net::HTTP.get_response(uri)
    if !response.is_a?(Net::HTTPSuccess)
      raise Error, "HTTP request failure!\n#{response.inspect}\n#{response.body.to_s}"
    end
    json_response = JSON.parse(response.body)
    json_response.each do |record|
      indices.push(record['index'])
    end
  end
  if opts[:exclude_indices]
    indices = indices.reject {|it| opts[:exclude_indices].include?(it) }
  end

  if indices.empty?
    raise Error, "no indices to back up!"
  end
  
  opts[:scroll] ||= '5m'
  opts[:size] ||= 1000
  
  # exclude _id by default.
  if !opts.key?(:exclude_fields)
    opts[:exclude_fields] = ['_id']
  end

  # validate backup path
  if File.exists?(path)
    if opts[:force]
      FileUtils.rmtree(path)
    else
      raise Error, "backup path '#{path}' already exists! Delete it first or use --force"
    end
  end
  FileUtils.mkdir_p(path)

  # dump data
  indices.each_with_index do |index_name, i|
    puts "(#{i+1}/#{indices.size}) backing up index #{index_name}" unless opts[:quiet]
    # initial request
    file_index = 0
    uri = URI(url + "/#{index_name}/_search")
    params = { 
      :format => "json",
      :scroll => opts[:scroll], 
      :size => opts[:size],
      :sort => ["_doc"] 
    }
    uri.query = URI.encode_www_form(params)
    # puts "HTTP REQUEST #{uri.inspect}"
    response = Net::HTTP.get_response(uri)
    if !response.is_a?(Net::HTTPSuccess)
      raise Error, "HTTP request failure!\n#{response.inspect}\n#{response.body.to_s}"
    end
    json_response = JSON.parse(response.body)
    raise Error, "No scroll_id returned in response:\n#{response.inspect}" unless json_response['_scroll_id']
    scroll_id = json_response['_scroll_id']
    hits = json_response['hits']['hits']
    save_bulk_data(path, hits, nil, opts)
    
    file_index = 1
    # scroll requests
    while !hits.empty?
      uri = URI(url + "/_search/scroll")
      params = {
        :scroll_id => scroll_id, 
        :scroll => opts[:scroll]
      }
      uri.query = URI.encode_www_form(params)
      # puts "HTTP REQUEST #{uri.inspect}"
      response = Net::HTTP.get_response(uri)
      if !response.is_a?(Net::HTTPSuccess)
        raise Error, "HTTP request failure!\n#{response.inspect}\n#{response.body.to_s}"
      end
      json_response = JSON.parse(response.body)
      raise Error, "No scroll_id returned in response:\n#{response.inspect}\n#{response.body.to_s}" unless json_response['_scroll_id']
      scroll_id = json_response['_scroll_id']
      hits = json_response['hits']['hits']
      save_bulk_data(path, hits, file_index, opts)
      file_index += 1
    end
  end
  
  puts "Finished backup of elasticsearch #{url} to directory #{backup_dir} (took #{(Time.now-start_time).round(3)}s)" unless opts[:quiet]
  return true
end

.restore(url, backup_dir, opts = {}) ⇒ true

Restore elasticsearch data from a backup. This will do a POST to the _bulk api for each file in the backup directory.

Examples:

Restore local cluster with our backup.


ElasticUtil.restore('http://localhost:9201', '/tmp/mybackup')

Parameters:

  • url (String) —

    The url of the elasticsearch cluster eg. ‘localhost:9200’.

  • backup_dir (String) —

    The backup directory.

  • opts (Hash) (defaults to: {}) —

    The options for this backup.

Options Hash (opts):

  • :quiet (true) —

    Don’t print anything. Default is false.

Returns:

  • (true) —

    or raises an error



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# File 'lib/elastic_util.rb', line 177

def self.restore(url, backup_dir, opts={})
  start_time = Time.now
  backup_dir = backup_dir.strip
  path = File.join(backup_dir.strip, DUMP_DIR)

  # validate backup path
  if !Dir.exists?(path)
    raise Error, "backup path '#{backup_dir}' does not exist!"
  end

  # ping it first
  uri = URI(url)
  response = Net::HTTP.get_response(uri)
  http = Net::HTTP.new(uri.host, uri.port)
  http.read_timeout = (60*3)
  http.open_timeout = 5
  response = http.start() {|http|
    http.get("/")
  }

  if !response.is_a?(Net::HTTPSuccess)
    raise Error, "Unable to reach elasticsearch at url '#{url}'!\n#{response.inspect}\n#{response.body.to_s}"
  end

  # find files to import
  found_files = Dir[File.join(path, '**', '*.json.data' )]
  if found_files.empty?
    raise Error, "backup path '#{backup_dir}' does not exist!"
  else
    puts "Found #{found_files.size} files to import" unless opts[:quiet]
  end

  # bulk api request for each file
  found_files.each_with_index do |file, i|
    puts "(#{i+1}/#{found_files.size}) bulk importing file #{file}" unless opts[:quiet]
    payload = File.read(file)
    # uri = URI(url)
    http = Net::HTTP.new(uri.host, uri.port)
    response = http.post("/_bulk", payload)
    if !response.is_a?(Net::HTTPSuccess)
      raise Error, "HTTP request failure!\n#{response.inspect}\n#{response.body.to_s}"
    end
  end

  puts "Finished restore of elasticsearch #{url} with backup #{backup_dir} (took #{(Time.now-start_time).round(3)}s)" unless opts[:quiet]
  return true
end

.save_bulk_data(path, hits, file_index = nil, opts = {}) ⇒ Object

:nodoc:



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# File 'lib/elastic_util.rb', line 225

def self.save_bulk_data(path, hits, file_index=nil, opts={}) # :nodoc:
  if hits && !hits.empty?
    hits.each do |hit|
      index_name = hit['_index']
      index_type = hit['_type']
      dir_name = File.join(path, index_name)
      FileUtils.mkdir_p(dir_name)
      file_name = File.join(dir_name, index_type) + (file_index ? "_#{file_index}" : "") + ".json.data"
      # prepare record for bulk api injection
      action_json = {'index' => {
        '_index' => hit['_index'], '_type' => hit['_type'], '_id' => hit['_id']
      } }
      source_json = hit['_source']
      if opts[:exclude_fields] && source_json
        opts[:exclude_fields].each do |field|
          source_json.delete(field)
        end
      end
      File.open(file_name, 'a') do |file|
        file.write JSON.generate(action_json) + "\n" + JSON.generate(source_json) + "\n"
      end
    end
  end
end