dev/livy-shell

#!/usr/bin/env python
#
# Very bare bones shell for driving a Livy session. Usage:
#
#   livy-shell url [option=value ...]
#
# Options are set directly in the session creation request, so they must match the names of fields
# in the CreateInteractiveRequest structure. Option values should be python-like objects (should be
# parseable by python's "eval" function; naked strings are allowed). For example:
#
#   kind=spark
#   jars=[ '/foo.jar', '/bar.jar' ]
#   conf={ foo : bar, 'spark.option' : opt_value }
#
# By default, a Spark (Scala) session is created.
#

import httplib
import json
import readline
import sys
import time
import urlparse

def check(condition, msg, *args):
  if not condition:
    if args:
      msg = msg % args
    print >> sys.stderr, msg
    sys.exit(1)


def message(msg, *args):
  if args:
    msg = msg % args
  print msg


class LiteralDict(dict):
  def __missing__(self, name):
    return name


def request(conn, method, uri, body):
  body = json.dumps(body) if body else None
  headers = { 'Content-Type' : 'application/json' }
  conn.request(method, uri, body=body, headers=headers)

  resp = conn.getresponse()
  data = resp.read()
  if resp.status < 200 or resp.status >= 400:
    raise httplib.HTTPException, (resp.status, resp.reason, data)
  if resp.status < 300 and resp.status != httplib.NO_CONTENT:
    return json.loads(data)
  return None


def get(conn, uri):
  return request(conn, 'GET', uri, None)


def post(conn, uri, body):
  return request(conn, 'POST', uri, body)


def delete(conn, uri):
  return request(conn, 'DELETE', uri, None)


def create_session(conn):
  request = {
    "kind" : "spark"
  }
  for opt in sys.argv[2:]:
    check(opt.find('=') > 0, "Invalid option: %s.", opt)
    key, value = opt.split('=', 1)
    request[key] = eval(value, LiteralDict())

  return post(conn, "/sessions", request)


def wait_for_idle(sid):
  session = get(conn, "/sessions/%d" % (sid, ))
  while session['state'] == 'starting':
    message("Session not ready yet (%s)", session['state'])
    time.sleep(5)
    session = get(conn, "/sessions/%d" % (sid, ))

  if session['state'] != 'idle':
    raise Exception, "Session failed to start."


def monitor_statement(conn, sid, s):
  cnt = 0
  while True:
    state = s['state']
    if state == 'available':
      output = s['output']
      status = output['status']
      if status == 'ok':
        result = output['data']
        text = result.get('text/plain', None)
        if text is None:
          message("Success (non-text result).")
        elif text.rstrip():
          message("%s", text)
      elif status == 'error':
        ename = output['ename']
        evalue = output['evalue']
        traceback = "\n".join(output.get('traceback', []))
        message("%s: %s", ename, evalue)
        if traceback:
          message("%s", traceback)
      else:
        message("Statement finished with unknown status '%s'.", status)
      break
    elif state == 'error':
      message("%s", s['error'])
      break
    else:
      if cnt == 10:
        message("(waiting for result...)")
        cnt = 0
      else:
        cnt += 1
      time.sleep(1)
      s = get(conn, "/sessions/%d/statements/%s" % (sid, s['id']))


def run_shell(conn, sid):
  while True:
    cmd = raw_input('> ')
    if cmd == "quit()":
      break

    statement = post(conn, "/sessions/%d/statements" % (sid, ), { 'code' : cmd })
    monitor_statement(conn, sid, statement)

def open_connection(url):
  if url.scheme == "https":
    return httplib.HTTPSConnection(url.netloc)
  else:
    return httplib.HTTPConnection(url.netloc)

#
# main()
#

check(len(sys.argv) > 1, "Missing arguments.")

url = urlparse.urlparse(sys.argv[1])
conn = open_connection(url)

sid = -1
try:
  message("Creating new session...")
  session = create_session(conn)
  sid = int(session['id'])
  message("New session (id = %d, kind = %s), waiting for idle state...", sid, session['kind'])
  wait_for_idle(sid)
  message("Session ready.")
  run_shell(conn,sid)
except EOFError:
  pass
finally:
  conn.close()
  if sid != -1:
    conn = open_connection(url)
    try:
      delete(conn, "/sessions/%d" % (sid, ))
    finally:
      conn.close()