The goal is to provide a stable, REST-based application submission gateway that is not inherently based on Akka, which is unstable across versions. This PR targets standalone cluster mode, but is implemented in a general enough manner that can be potentially extended to other modes in the future. Client mode is currently not included in the changes here because there are many more Akka messages exchanged there.

As of the changes here, the Master will advertise two ports, 7077 and 6066. We need to keep around the old one (7077) for client mode and older versions of Spark submit. However, all new versions of Spark submit will use the REST gateway (6066).

By the way this includes ~700 lines of tests and ~200 lines of license.

Author: Andrew Or <andrew@databricks.com>

Closes #4216 from andrewor14/rest and squashes the following commits:

8d7ce07 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
6f0c597 [Andrew Or] Use nullable fields for integer and boolean values
dfe4bd7 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
b9e2a08 [Andrew Or] Minor comments
02b5cea [Andrew Or] Fix tests
d2b1ef8 [Andrew Or] Comment changes + minor code refactoring across the board
9c82a36 [Andrew Or] Minor comment and wording updates
b4695e7 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
c9a8ad7 [Andrew Or] Do not include appResource and mainClass as properties
6fc7670 [Andrew Or] Report REST server response back to the user
40e6095 [Andrew Or] Pass submit parameters through system properties
cbd670b [Andrew Or] Include unknown fields, if any, in server response
9fee16f [Andrew Or] Include server protocol version on mismatch
09f873a [Andrew Or] Fix style
8188e61 [Andrew Or] Upgrade Jackson from 2.3.0 to 2.4.4
37538e0 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
9165ae8 [Andrew Or] Fall back to Akka if endpoint was not REST
252d53c [Andrew Or] Clean up server error handling behavior further
c643f64 [Andrew Or] Fix style
bbbd329 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
792e112 [Andrew Or] Use specific HTTP response codes on error
f98660b [Andrew Or] Version the protocol and include it in REST URL
721819f [Andrew Or] Provide more REST-like interface for submit/kill/status
581f7bf [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
9e0d1af [Andrew Or] Move some classes around to reduce number of files (minor)
42e5de4 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
1f1c03f [Andrew Or] Use Jackson's DefaultScalaModule to simplify messages
9229433 [Andrew Or] Reduce duplicate naming in REST field
ade28fd [Andrew Or] Clean up REST response output in Spark submit
b2fef8b [Andrew Or] Abstract the success field to the general response
6c57b4b [Andrew Or] Increase timeout in end-to-end tests
bf696ff [Andrew Or] Add checks for enabling REST when using kill/status
7ee6737 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
e2f7f5f [Andrew Or] Provide more safeguard against missing fields
9581df7 [Andrew Or] Clean up uses of exceptions
914fdff [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
e2104e6 [Andrew Or] stable -> rest
3db7379 [Andrew Or] Fix comments and name fields for better error messages
8d43486 [Andrew Or] Replace SubmitRestProtocolAction with class name
df90e8b [Andrew Or] Use Jackson for JSON de/serialization
d7a1f9f [Andrew Or] Fix local cluster tests
efa5e18 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
e42c131 [Andrew Or] Add end-to-end tests for standalone REST protocol
837475b [Andrew Or] Show the REST port on the Master UI
d8d3717 [Andrew Or] Use a daemon thread pool for REST server
6568ca5 [Andrew Or] Merge branch 'master' of github.com:apache/spark into rest
77774ba [Andrew Or] Minor fixes
206cae4 [Andrew Or] Refactor and add tests for the REST protocol
63c05b3 [Andrew Or] Remove MASTER as a field (minor)
9e21b72 [Andrew Or] Action -> SparkSubmitAction (minor)
51c5ca6 [Andrew Or] Distinguish client and server side Spark versions
b44e103 [Andrew Or] Implement status requests + fix validation behavior
120ab9d [Andrew Or] Support kill and request driver status through SparkSubmit
544de1d [Andrew Or] Major clean ups in code and comments
e958cae [Andrew Or] Supported nested values in messages
484bd21 [Andrew Or] Specify an ordering for fields in SubmitDriverRequestMessage
6ff088d [Andrew Or] Rename classes to generalize REST protocol
af9d9cb [Andrew Or] Integrate REST protocol in standalone mode
53e7c0e [Andrew Or] Initial client, server, and all the messages