Class: Jets::PolyFun::BaseExecutor

Inherits:
Object
  • Object
show all
Extended by:
Memoist
Defined in:
lib/jets/poly_fun/base_executor.rb

Direct Known Subclasses

NodeExecutor, PythonExecutor

Instance Method Summary collapse

Constructor Details

#initialize(task) ⇒ BaseExecutor

Returns a new instance of BaseExecutor.



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# File 'lib/jets/poly_fun/base_executor.rb', line 8

def initialize(task)
  @task = task
end

Instance Method Details

#cleanup ⇒ Object 



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# File 'lib/jets/poly_fun/base_executor.rb', line 112

def cleanup
  FileUtils.rm_rf(@temp_dir) unless ENV['KEEP_LAMBDA_WRAPPER']
end

#copy_src_to_temp ⇒ Object 



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# File 'lib/jets/poly_fun/base_executor.rb', line 39

def copy_src_to_temp
  app_class = @task.class_name.constantize
  internal = app_class.respond_to?(:internal) && app_class.internal
  src = internal ?
    "#{File.expand_path("../internal", File.dirname(__FILE__))}/#{@task.poly_src_path}" :
    "#{Jets.root}/#{@task.poly_src_path}"
  dest = "#{@temp_dir}/#{@task.poly_src_path}"

  FileUtils.mkdir_p(File.dirname(dest))
  FileUtils.cp(src, dest)
end

#create_tmpdir ⇒ Object

Mimic Dir.mktmpdir randomness, not using Dir.mktmpdir because that generates the folder at the /tmp level only.



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# File 'lib/jets/poly_fun/base_executor.rb', line 32

def create_tmpdir
  random = "#{Time.now.strftime("%Y%d%H")}-#{Process.pid}-#{SecureRandom.hex[0..6]}"
  tmpdir = "#{Jets.build_root}/executor/#{random}"
  FileUtils.mkdir_p(tmpdir)
  tmpdir
end

#handler ⇒ Object 



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# File 'lib/jets/poly_fun/base_executor.rb', line 116

def handler
  # Must use the generated CloudFormation template to get the handler because
  # the handler is derived from mutiple sources.
  resource = Jets::Resource::Lambda::Function.new(@task)
  full_handler = resource.properties["Handler"] # full handler here
  File.extname(full_handler).sub(/^./,'') # the extension of the full handler is the handler
end

#lambda_executor_script ⇒ Object 



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# File 'lib/jets/poly_fun/base_executor.rb', line 51

def lambda_executor_script
  File.dirname("#{@temp_dir}/#{@task.poly_src_path}") + "/lambda_executor" + @task.lang_ext
end

#run(event, context) ⇒ Object

Handler is in properties:

  1. copy lambda function into tmp folder

  2. generate Lang wrapper script

  3. call wrapper script from ruby. Handle stdout and stderr and result. Pass info back to ruby



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# File 'lib/jets/poly_fun/base_executor.rb', line 16

def run(event, context)
  @temp_dir = create_tmpdir
  copy_src_to_temp
  write(code)
  result = run_lambda_executor(event, context)
  cleanup
  result
end

#run_lambda_executor(event, context) ⇒ Object

When polymorphic method errors, this method reproduces an error in the lambda format Here’s some examples to help example:

Example of what the raw python prints out to stderr:

Traceback (most recent call last):
  File "/tmp/jets/lite/executor/20180804-10727-mcs6qk/lambda_executor.py", line 6, in <module>
    resp = handle(event, context)
  File "/tmp/jets/lite/executor/20180804-10727-mcs6qk/index.py", line 22, in handle
    return response({'message': e.message}, 400)
  File "/tmp/jets/lite/executor/20180804-10727-mcs6qk/index.py", line 5, in response
    badcode
NameError: global name 'badcode' is not defined

So last line has the error summary info. Other lines have stack trace after the Traceback indicator.

Example of the reproduced lambda error format:

{
  "errorMessage": "'NameError' object has no attribute 'message'",
  "errorType": "AttributeError",
  "stackTrace": [
    [
      "/var/task/handlers/controllers/posts_controller/python/index.py",
      22,
      "handle",
      "return response({'message': e.message}, 400)"
    ]
  ]
}



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# File 'lib/jets/poly_fun/base_executor.rb', line 86

def run_lambda_executor(event, context)
  interpreter = @task.lang
  command = %Q|#{interpreter} #{lambda_executor_script} '#{JSON.dump(event)}' '#{JSON.dump(context)}'|
  stdout, stderr, status = Open3.capture3(command)
  # puts "=> #{command}".color(:green)
  # puts "stdout #{stdout}"
  # puts "stderr #{stderr}"
  # puts "status #{status}"
  if status.success?
    stdout
  else
    # We'll mimic the way lambda displays an error.
    # $stderr.puts(stderr) # uncomment to debug
    error_lines = stderr.split("\n")
    error_message = error_lines.pop
    error_type = error_message.split(':').first
    error_lines.shift # remove first line that has the Traceback
    stack_trace = error_lines.reverse # python shows stack trace in opposite order from ruby
    JSON.dump(
      "errorMessage" => error_message,
      "errorType" => error_type, # hardcode
      "stackTrace" => stack_trace
    )
  end
end

#write(code) ⇒ Object 



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# File 'lib/jets/poly_fun/base_executor.rb', line 25

def write(code)
  puts "lambda_executor_script #{lambda_executor_script}" if ENV['KEEP_LAMBDA_WRAPPER']
  IO.write(lambda_executor_script, code)
end