Class: LogStash::Inputs::LogstashInputAzureblob

Inherits:
Base
  • Object
show all
Defined in:
lib/logstash/inputs/azureblob.rb

Overview

Logstash input plugin for Azure Blobs

This logstash plugin gathers data from Microsoft Azure Blobs

Constant Summary collapse

MAX =

Constant of max integer

2 ** ([42].pack('i').size * 16 - 2 ) -1
UPDATE_REGISTRY_COUNT =

Update the registry offset each time after this number of entries have been processed

100

Instance Method Summary collapse

Instance Method Details

#acquire_lease(blob_name, retry_times = 60, interval_sec = 1) ⇒ Object

Acquire a lease on a blob item with retries.

By default, it will retry 60 times with 1 second interval.



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# File 'lib/logstash/inputs/azureblob.rb', line 302

def acquire_lease(blob_name, retry_times = 60, interval_sec = 1)
  lease = nil;
  retried = 0;
  while lease.nil? do
    begin
      lease = @azure_blob.acquire_blob_lease(@container, blob_name, { :timeout => 60, :duration => @registry_lease_duration })
    rescue StandardError => e
      if(e.type && e.type == 'LeaseAlreadyPresent')
        if (retried > retry_times)
          raise
        end
        retried += 1
        sleep interval_sec
      else
        # Anything else happend other than 'LeaseAlreadyPresent', break the lease. This is a work-around for the behavior that when
        # timeout exception is hit, somehow, a infinite lease will be put on the lock file.
        @azure_blob.break_blob_lease(@container, blob, { :break_period => 30 })
      end
    end
  end #while
  return lease
end

#cleanup_registry ⇒ Object

Clean up the registry.



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# File 'lib/logstash/inputs/azureblob.rb', line 414

def cleanup_registry
  begin
    lease = nil
    lease = acquire_lease(@registry_locker)
    registry_hash = load_registry
    registry_hash.each { | key, registry_item|
      registry_item.reader = nil if registry_item.reader == @reader
    }
    save_registry(registry_hash)
    @azure_blob.release_blob_lease(@container, @registry_locker, lease)
    lease = nil
  rescue StandardError => e
    @logger.error("Oh My, An error occurred. #{e}:\n#{e.backtrace}", :exception => e)
  ensure
    @azure_blob.release_blob_lease(@container, @registry_locker, lease) unless lease.nil?
    lease = nil
  end #rescue
end

#create_registry(blob_items) ⇒ Object

Create a registry file to coordinate between multiple azure blob inputs.



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# File 'lib/logstash/inputs/azureblob.rb', line 434

def create_registry (blob_items)
  registry_hash = Hash.new

  blob_items.each do |blob_item|
      initial_offset = 0
      initial_offset = blob_item.properties[:content_length] if @registry_create_policy == 'resume'
      registry_item = LogStash::Inputs::RegistryItem.new(blob_item.name, blob_item.properties[:etag], nil, initial_offset, 0)
    registry_hash[blob_item.name] = registry_item
  end # each
  save_registry(registry_hash)
  return registry_hash
end

#deserialize_registry_hash(json_string) ⇒ Object

Deserialize registry hash from json string.



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# File 'lib/logstash/inputs/azureblob.rb', line 250

def deserialize_registry_hash (json_string)
  result = Hash.new
  temp_hash = JSON.parse(json_string)
  temp_hash.values.each { |kvp|
    result[kvp['file_path']] = LogStash::Inputs::RegistryItem.new(kvp['file_path'], kvp['etag'], kvp['reader'], kvp['offset'], kvp['gen'])
  }
  return result
end

#enqueue_content(queue, content, header, tail) ⇒ Object

process



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# File 'lib/logstash/inputs/azureblob.rb', line 217

def enqueue_content(queue, content, header, tail)
  if (header.nil? || header.length == 0) && (tail.nil? || tail.length == 0)
    #skip some unnecessary copying
    full_content = content
  else
    full_content = ""
    full_content << header unless header.nil? || header.length == 0
    full_content << content
    full_content << tail unless tail.nil? || tail.length == 0
  end
  
  @codec.decode(full_content) do |event|
    decorate(event)
    queue << event
  end 
end

#list_all_blobs ⇒ Object

List all the blobs in the given container.



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# File 'lib/logstash/inputs/azureblob.rb', line 260

def list_all_blobs
  blobs = Set.new []
  continuation_token = NIL
  @blob_list_page_size = 100 if @blob_list_page_size <= 0
  loop do
    # Need to limit the returned number of the returned entries to avoid out of memory exception.
    entries = @azure_blob.list_blobs(@container, { :timeout => 60, :marker => continuation_token, :max_results => @blob_list_page_size })
    entries.each do |entry|
      blobs << entry
    end # each
    continuation_token = entries.continuation_token
    break if continuation_token.empty?
  end # loop
  return blobs
end

#load_registry ⇒ Object

Load the content of the registry into the registry hash and return it.



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# File 'lib/logstash/inputs/azureblob.rb', line 448

def load_registry
  # Get content
  registry_blob, registry_blob_body = @azure_blob.get_blob(@container, @registry_path)
  registry_hash = deserialize_registry_hash(registry_blob_body)
  return registry_hash
end

#on_entry_processed(start_index, content_length, blob_name, new_etag, gen) ⇒ Object 



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# File 'lib/logstash/inputs/azureblob.rb', line 234

def on_entry_processed(start_index, content_length, blob_name, new_etag, gen)
  @processed_entries = @processed_entries + 1
  if @processed_entries % UPDATE_REGISTRY_COUNT == 0
    request_registry_update(start_index, content_length, blob_name, new_etag, gen)
  end
end

#process(queue) ⇒ Object

Start processing the next item.



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# File 'lib/logstash/inputs/azureblob.rb', line 152

def process(queue)
  begin
    @processed_entries = 0
    blob, start_index, gen = register_for_read

    if(!blob.nil?)
      begin
        blob_name = blob.name
        @logger.debug("Processing blob #{blob.name}")
        blob_size = blob.properties[:content_length]
        # Work-around: After returned by get_blob, the etag will contains quotes.
        new_etag = blob.properties[:etag]
        # ~ Work-around

        blob, header = @azure_blob.get_blob(@container, blob_name, {:end_range => (@file_head_bytes-1) }) if header.nil? unless @file_head_bytes.nil? or @file_head_bytes <= 0

        blob, tail = @azure_blob.get_blob(@container, blob_name, {:start_range => blob_size - @file_tail_bytes}) if tail.nil? unless @file_tail_bytes.nil? or @file_tail_bytes <= 0

        if start_index == 0
          # Skip the header since it is already read.
          start_index = @file_head_bytes
        end

        @logger.debug("start index: #{start_index} blob size: #{blob_size}")

        content_length = 0
        blob_reader = BlobReader.new(@logger, @azure_blob, @container, blob_name, file_chunk_size_bytes, start_index, blob_size - 1 - @file_tail_bytes)

        is_json_codec = (defined?(LogStash::Codecs::JSON) == 'constant') && (@codec.is_a? LogStash::Codecs::JSON)
        if is_json_codec
          parser = JsonParser.new(@logger, blob_reader)

          parser.parse(->(json_content) {
            content_length = content_length + json_content.length

            enqueue_content(queue, json_content, header, tail)

            on_entry_processed(start_index, content_length, blob_name, new_etag, gen)
          }, ->(malformed_json) {
            @logger.debug("Skipping #{malformed_json.length} malformed bytes")
            content_length = content_length + malformed_json.length

            on_entry_processed(start_index, content_length, blob_name, new_etag, gen)
          })
        else
          begin
            content, are_more_bytes_available = blob_reader.read

            content_length = content_length + content.length
            enqueue_content(queue, content, header, tail)

            on_entry_processed(start_index, content_length, blob_name, new_etag, gen)
          end until !are_more_bytes_available || content.nil?

        end #if
      ensure
        # Making sure the reader is removed from the registry even when there's exception.
        request_registry_update(start_index, content_length, blob_name, new_etag, gen)
      end # begin
    end # if
  rescue => e
    @logger.error("Oh My, An error occurred. Error:#{e}: Trace: #{e.backtrace}", :exception => e)
  end # begin
end

#raise_gen(registry_hash, file_path) ⇒ Object

Raise generation for blob in registry



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# File 'lib/logstash/inputs/azureblob.rb', line 277

def raise_gen(registry_hash, file_path)
  begin
    target_item = registry_hash[file_path]
    begin
      target_item.gen += 1
      # Protect gen from overflow.
      target_item.gen = target_item.gen / 2 if target_item.gen == MAX
    rescue StandardError => e
      @logger.error("Fail to get the next generation for target item #{target_item}.", :exception => e)
      target_item.gen = 0
    end

    min_gen_item = registry_hash.values.min_by { |x| x.gen }
    while min_gen_item.gen > 0
      registry_hash.values.each { |value| 
        value.gen -= 1
      }
      min_gen_item = registry_hash.values.min_by { |x| x.gen }
    end
  end
end

#register ⇒ Object 



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# File 'lib/logstash/inputs/azureblob.rb', line 122

def register
  user_agent = "logstash-input-azureblob"
  user_agent << "/" << Gem.latest_spec_for("logstash-input-azureblob").version.to_s
  
  # this is the reader # for this specific instance.
  @reader = SecureRandom.uuid
  @registry_locker = "#{@registry_path}.lock"
 
  # Setup a specific instance of an Azure::Storage::Client
  client = Azure::Storage::Client.create(:storage_account_name => @storage_account_name, :storage_access_key => @storage_access_key, :storage_blob_host => "https://#{@storage_account_name}.blob.#{@endpoint}", :user_agent_prefix => user_agent)
  # Get an azure storage blob service object from a specific instance of an Azure::Storage::Client
  @azure_blob = client.blob_client
  # Add retry filter to the service object
  @azure_blob.with_filter(Azure::Storage::Core::Filter::ExponentialRetryPolicyFilter.new)
end

#register_for_read ⇒ Object

Return the next blob for reading as well as the start index.



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# File 'lib/logstash/inputs/azureblob.rb', line 326

def register_for_read
  begin
    all_blobs = list_all_blobs
    registry = all_blobs.find { |item| item.name.downcase == @registry_path  }
    registry_locker = all_blobs.find { |item| item.name.downcase == @registry_locker }

    candidate_blobs = all_blobs.select { |item| (item.name.downcase != @registry_path) && ( item.name.downcase != @registry_locker ) }
    
    start_index = 0
    gen = 0
    lease = nil

    # Put lease on locker file than the registy file to allow update of the registry as a workaround for Azure Storage Ruby SDK issue # 16.
    # Workaround: https://github.com/Azure/azure-storage-ruby/issues/16
    registry_locker = @azure_blob.create_block_blob(@container, @registry_locker, @reader) if registry_locker.nil?
    lease = acquire_lease(@registry_locker)
    # ~ Workaround

    if(registry.nil?)
      registry_hash = create_registry(candidate_blobs)
    else
      registry_hash = load_registry
    end #if
      
    picked_blobs = Set.new []
    # Pick up the next candidate
    picked_blob = nil
    candidate_blobs.each { |candidate_blob|
      @logger.debug("candidate_blob: #{candidate_blob.name} content length: #{candidate_blob.properties[:content_length]}")
      registry_item = registry_hash[candidate_blob.name]

      # Appending items that doesn't exist in the hash table
      if registry_item.nil?
        registry_item = LogStash::Inputs::RegistryItem.new(candidate_blob.name, candidate_blob.properties[:etag], nil, 0, 0)
        registry_hash[candidate_blob.name] = registry_item
      end # if
      @logger.debug("registry_item offset: #{registry_item.offset}")
      if ((registry_item.offset < candidate_blob.properties[:content_length]) && (registry_item.reader.nil? || registry_item.reader == @reader))
        @logger.debug("candidate_blob picked: #{candidate_blob.name} content length: #{candidate_blob.properties[:content_length]}")
        picked_blobs << candidate_blob
      end
    }

    picked_blob = picked_blobs.min_by { |b| registry_hash[b.name].gen }
    if !picked_blob.nil?
      registry_item = registry_hash[picked_blob.name]
      registry_item.reader = @reader
      registry_hash[picked_blob.name] = registry_item
      start_index = registry_item.offset
      raise_gen(registry_hash, picked_blob.name)
      gen = registry_item.gen
    end #if

    # Save the chnage for the registry
    save_registry(registry_hash)
    
    @azure_blob.release_blob_lease(@container, @registry_locker, lease)
    lease = nil;

    return picked_blob, start_index, gen
  rescue StandardError => e
    @logger.error("Oh My, An error occurred. #{e}: #{e.backtrace}", :exception => e)
    return nil, nil, nil
  ensure
    @azure_blob.release_blob_lease(@container, @registry_locker, lease) unless lease.nil?
    lease = nil
  end # rescue
end

#request_registry_update(start_index, content_length, blob_name, new_etag, gen) ⇒ Object 



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# File 'lib/logstash/inputs/azureblob.rb', line 241

def request_registry_update(start_index, content_length, blob_name, new_etag, gen)
  new_offset = start_index
  new_offset = new_offset + content_length unless content_length.nil?
  @logger.debug("New registry offset: #{new_offset}")
  new_registry_item = LogStash::Inputs::RegistryItem.new(blob_name, new_etag, nil, new_offset, gen)
  update_registry(new_registry_item)
end

#run(queue) ⇒ Object

def register



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# File 'lib/logstash/inputs/azureblob.rb', line 138

def run(queue)
  # we can abort the loop if stop? becomes true
  while !stop?
    process(queue)
    @logger.debug("Hitting interval of #{@interval}ms . . .")
    Stud.stoppable_sleep(@interval) { stop? }
  end # loop
end

#save_registry(registry_hash) ⇒ Object

Serialize the registry hash and save it.



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# File 'lib/logstash/inputs/azureblob.rb', line 456

def save_registry(registry_hash)
  # Serialize hash to json
  registry_hash_json = JSON.generate(registry_hash)

  # Upload registry to blob
  @azure_blob.create_block_blob(@container, @registry_path, registry_hash_json)
end

#stop ⇒ Object

def run



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# File 'lib/logstash/inputs/azureblob.rb', line 147

def stop
  cleanup_registry
end

#update_registry(registry_item) ⇒ Object

Update the registry



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# File 'lib/logstash/inputs/azureblob.rb', line 396

def update_registry (registry_item)
  begin
    lease = nil
    lease = acquire_lease(@registry_locker)
    registry_hash = load_registry
    registry_hash[registry_item.file_path] = registry_item
    save_registry(registry_hash)
    @azure_blob.release_blob_lease(@container, @registry_locker, lease)
    lease = nil
  rescue StandardError => e
    @logger.error("Oh My, An error occurred. #{e}:\n#{e.backtrace}", :exception => e)
  ensure
    @azure_blob.release_blob_lease(@container, @registry_locker, lease) unless lease.nil?
    lease = nil
  end #rescue
end