Class: Elasticsearch::Rails::HA::IndexStager

Inherits:
Object
  • Object
show all
Defined in:
lib/elasticsearch/rails/ha/index_stager.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(klass) ⇒ IndexStager

Returns a new instance of IndexStager.



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 7

def initialize(klass)
  @klass = klass.constantize
end

Instance Attribute Details

#klass ⇒ Object (readonly)

Returns the value of attribute klass.



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 5

def klass
  @klass
end

#live_index_name ⇒ Object (readonly)

Returns the value of attribute live_index_name.



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 5

def live_index_name
  @live_index_name
end

Instance Method Details

#alias_stage_to_tmp_index ⇒ Object 



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 24

def alias_stage_to_tmp_index
  es_client.indices.delete index: stage_index_name rescue false
  es_client.indices.update_aliases body: {
    actions: [
      { add: { index: tmp_index_name, alias: stage_index_name } }
    ]
  }
end

#promote(live_index_name = klass.index_name) ⇒ Object 



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 33

def promote(live_index_name=klass.index_name)
  @live_index_name = live_index_name

  # the renaming actions (performed atomically by ES)
  rename_actions = [
    { remove: { index: stage_aliased_to, alias: stage_index_name } },
    {    add: { index: stage_index_name, alias: live_index_name } }
  ]

  # zap any existing index known as index_name,
  # but do it conditionally since it is reasonable that it does not exist.
  to_delete = []
  existing_live_index = es_client.indices.get_aliases(index: live_index_name)
  existing_live_index.each do |k,v|

    # if the index is merely aliased, remove its alias as part of the aliasing transaction.
    if k != klass.index_name
      rename_actions.unshift({ remove: { index: k, alias: live_index_name } })

      # mark it for deletion when we've successfully updated aliases
      to_delete.push k

    else
      # this is a real, unaliased index with this name, so it must be deleted.
      # (This usually happens the first time we implement the aliasing scheme against
      # an existing installation.)
      es_client.indices.delete index: live_index_name rescue false
    end
  end

  # re-alias
  es_client.indices.update_aliases body: { actions: rename_actions }

  # clean up
  to_delete.each do |idxname|
    es_client.indices.delete index: idxname rescue false
  end
end

#stage_index_name ⇒ Object 



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 11

def stage_index_name
  if klass.respond_to?(:stage_index_name)
    klass.stage_index_name
  else
    klass.index_name + "_staged"
  end
end

#tmp_index_name ⇒ Object 



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# File 'lib/elasticsearch/rails/ha/index_stager.rb', line 19

def tmp_index_name
  @_suffix ||= Time.now.strftime('%Y%m%d%H%M%S') + '-' + SecureRandom.hex[0..7]
  "#{klass.index_name}_#{@_suffix}"
end