option_parser.py

#!/usr/bin/env python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

# Example .impalarc file:
#
# [impala]
# impalad=localhost:21002
# verbose=false
#
# [impala.query_options]
# EXPLAIN_LEVEL=2
# MT_DOP=2

import ConfigParser
import sys
from impala_shell_config_defaults import impala_shell_defaults
from optparse import OptionParser


class ConfigFileFormatError(Exception):
  """Raised when the config file cannot be read by ConfigParser."""
  pass


class InvalidOptionValueError(Exception):
  """Raised when an option contains an invalid value."""
  pass


def parse_bool_option(value):
  """Returns True for '1' and 'True', and False for '0' and 'False'.
     Throws ValueError for other values.
  """
  if value.lower() in ["true", "1"]:
    return True
  elif value.lower() in ["false", "0"]:
    return False
  else:
    raise InvalidOptionValueError("Unexpected value in configuration file. '" + value
      + "' is not a valid value for a boolean option.")


def parse_shell_options(options, defaults, option_list):
  """Filters unknown options and converts some values from string to their corresponding
     python types (booleans and None).  'option_list' contains the list of valid options,
     and 'defaults' is used to deduce the type of some options (only bool at the moment).

     Returns a dictionary with option names as keys and option values as values.
  """
  result = {}
  option_dests = dict((opt.dest, opt) for opt in option_list)
  for option, value in options:
    opt = option_dests.get(option)
    if opt is None:
        print >> sys.stderr, "WARNING: Unable to read configuration file correctly. " \
          "Ignoring unrecognized config option: '%s'\n" % option
    elif isinstance(defaults.get(option), bool) or \
        opt.action == "store_true" or opt.action == "store_false":
      result[option] = parse_bool_option(value)
    elif opt.action == "append":
      result[option] = value.split(",%s=" % option)
    elif value.lower() == "none":
      result[option] = None
    else:
      result[option] = value
  return result


def get_config_from_file(config_filename, option_list):
  """Reads contents of configuration file

  Two config sections are supported:
  "[impala]":
  Overrides the defaults of the shell arguments. Unknown options are filtered
  and some values are converted from string to their corresponding python types
  (booleans and None).

  Multiple flags are appended with ",option_name=" as its delimiter, e.g.
  The delimiter is for multiple options is ,<option>=. For example:
  var=msg1=hello,var=msg2=world. 

  Setting 'config_filename' in the config file would have no effect,
  so its original value is kept.

  "[impala.query_options]"
  Overrides the defaults of the query options. Not validated here,
  because validation will take place after connecting to impalad.

  Returns a pair of dictionaries (shell_options, query_options), with option names
  as keys and option values as values.
  """
  config = ConfigParser.ConfigParser()
  try:
    config.read(config_filename)
  except Exception, e:
    raise ConfigFileFormatError(
      "Unable to read configuration file correctly. Check formatting: %s" % e)

  shell_options = {}
  if config.has_section("impala"):
    shell_options = parse_shell_options(config.items("impala"), impala_shell_defaults,
                                        option_list)
    if "config_file" in shell_options:
      print >> sys.stderr, "WARNING: Option 'config_file' can be only set from shell."
      shell_options["config_file"] = config_filename

  try:
    config.read(config_filename)
  except Exception, e:
    raise ConfigFileFormatError(
      "Unable to read configuration file correctly. Check formatting: %s" % e)

  query_options = {}
  if config.has_section("impala.query_options"):
    # Query option keys must be "normalized" to upper case before updating with
    # options coming from command line.
    query_options = dict(
      [(k.upper(), v) for k, v in config.items("impala.query_options")])
  return shell_options, query_options


def get_option_parser(defaults):
  """Creates OptionParser and adds shell options (flags)

  Default values are loaded in initially
  """

  parser = OptionParser()
  parser.set_defaults(**defaults)

  parser.add_option("-i", "--impalad", dest="impalad",
                    help="<host:port> of impalad to connect to \t\t")
  parser.add_option("-b", "--kerberos_host_fqdn", dest="kerberos_host_fqdn",
                    help="If set, overrides the expected hostname of the Impalad's "
                         "kerberos service principal. impala-shell will check that "
                         "the server's principal matches this hostname. This may be "
                         "used when impalad is configured to be accessed via a "
                         "load-balancer, but it is desired for impala-shell to talk "
                         "to a specific impalad directly.")
  parser.add_option("-q", "--query", dest="query",
                    help="Execute a query without the shell")
  parser.add_option("-f", "--query_file", dest="query_file",
                    help="Execute the queries in the query file, delimited by ;."
                         " If the argument to -f is \"-\", then queries are read from"
                         " stdin and terminated with ctrl-d.")
  parser.add_option("-k", "--kerberos", dest="use_kerberos",
                    action="store_true", help="Connect to a kerberized impalad")
  parser.add_option("-o", "--output_file", dest="output_file",
                    help=("If set, query results are written to the "
                          "given file. Results from multiple semicolon-terminated "
                          "queries will be appended to the same file"))
  parser.add_option("-B", "--delimited", dest="write_delimited",
                    action="store_true",
                    help="Output rows in delimited mode")
  parser.add_option("--print_header", dest="print_header",
                    action="store_true",
                    help="Print column names in delimited mode"
                         " when pretty-printed.")
  parser.add_option("--output_delimiter", dest="output_delimiter",
                    help="Field delimiter to use for output in delimited mode")
  parser.add_option("-s", "--kerberos_service_name",
                    dest="kerberos_service_name",
                    help="Service name of a kerberized impalad")
  parser.add_option("-V", "--verbose", dest="verbose",
                    action="store_true",
                    help="Verbose output")
  parser.add_option("-p", "--show_profiles", dest="show_profiles",
                    action="store_true",
                    help="Always display query profiles after execution")
  parser.add_option("--quiet", dest="verbose",
                    action="store_false",
                    help="Disable verbose output")
  parser.add_option("-v", "--version", dest="version",
                    action="store_true",
                    help="Print version information")
  parser.add_option("-c", "--ignore_query_failure", dest="ignore_query_failure",
                    action="store_true", help="Continue on query failure")
  parser.add_option("-d", "--database", dest="default_db",
                    help="Issues a use database command on startup \t")
  parser.add_option("-l", "--ldap", dest="use_ldap",
                    action="store_true",
                    help="Use LDAP to authenticate with Impala. Impala must be configured"
                    " to allow LDAP authentication. \t\t")
  parser.add_option("-u", "--user", dest="user",
                    help="User to authenticate with.")
  parser.add_option("--ssl", dest="ssl",
                    action="store_true",
                    help="Connect to Impala via SSL-secured connection \t")
  parser.add_option("--ca_cert", dest="ca_cert",
                    help=("Full path to "
                    "certificate file used to authenticate Impala's SSL certificate."
                    " May either be a copy of Impala's certificate (for self-signed "
                    "certs) or the certificate of a trusted third-party CA. If not set, "
                    "but SSL is enabled, the shell will NOT verify Impala's server "
                    "certificate"))
  parser.add_option("--config_file", dest="config_file",
                    help=("Specify the configuration file to load options. "
                          "The following sections are used: [impala], "
                          "[impala.query_options]. Section names are case sensitive. "
                          "Specifying this option within a config file will have "
                          "no effect. Only specify this as an option in the commandline."
                          ))
  parser.add_option("--history_file", dest="history_file",
                    help=("The file in which to store shell history. This may also be "
                          "configured using the IMPALA_HISTFILE environment variable."))
  parser.add_option("--live_summary", dest="print_summary", action="store_true",
                    help="Print a query summary every 1s while the query is running.")
  parser.add_option("--live_progress", dest="print_progress", action="store_true",
                    help="Print a query progress every 1s while the query is running.")
  parser.add_option("--auth_creds_ok_in_clear", dest="creds_ok_in_clear",
                    action="store_true", help="If set, LDAP authentication " +
                    "may be used with an insecure connection to Impala. " +
                    "WARNING: Authentication credentials will therefore be sent " +
                    "unencrypted, and may be vulnerable to attack.")
  parser.add_option("--ldap_password_cmd", dest="ldap_password_cmd",
                    help="Shell command to run to retrieve the LDAP password")
  parser.add_option("--var", dest="keyval", action="append",
                    help="Defines a variable to be used within the Impala session."
                         " Can be used multiple times to set different variables."
                         " It must follow the pattern \"KEY=VALUE\","
                         " KEY starts with an alphabetic character and"
                         " contains alphanumeric characters or underscores.")
  parser.add_option("-Q", "--query_option", dest="query_options", action="append",
                    help="Sets the default for a query option."
                         " Can be used multiple times to set different query options."
                         " It must follow the pattern \"KEY=VALUE\","
                         " KEY must be a valid query option. Valid query options "
                         " can be listed by command 'set'.")
  parser.add_option("-t", "--client_connect_timeout_ms",
                    help="Timeout in milliseconds after which impala-shell will time out"
                    " if it fails to connect to Impala server. Set to 0 to disable any"
                    " timeout.")
  # add default values to the help text
  for option in parser.option_list:
    # since the quiet flag is the same as the verbose flag
    # we need to make sure to print the opposite value for it
    # (print quiet is false since verbose is true)
    if option == parser.get_option('--quiet'):
      option.help += " [default: %s]" % (not defaults['verbose'])
    elif option != parser.get_option('--help'):
      # don't want to print default value for help
      option.help += " [default: %default]"

  return parser