freeipa/ipaserver/advise/base.py

# Authors: Tomas Babej <tbabej@redhat.com>
#
# Copyright (C) 2013  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

from __future__ import print_function

import os
from textwrap import wrap

from ipalib import api
from ipalib.plugable import Plugin, API
from ipalib.errors import ValidationError
from ipaplatform.paths import paths
from ipapython import admintool
from ipapython.ipa_log_manager import log_mgr


"""
To add configuration instructions for a new use case, define a new class that
inherits from Advice class.

You should create a plugin file for it in ipaserver/advise/plugins folder.

The class can run any arbitrary code or IPA command via api.Command['command']()
calls. It needs to override get_info() method, which returns the formatted
advice string.

Important! Do not forget to register the class to the API.

>>> @register()
>>> class sample_advice(Advice):
>>>     description = 'Instructions for machine with SSSD 1.0 setup.'

Description provided shows itself as a header and in the list of all advices
currently available via ipa-advise.

Optionally, you can require root privileges for your plugin:

>>>     require_root = True

The following method should be implemented in your plugin:

>>>     def get_info():
>>>         self.log.debug('Entering execute() method')
>>>         self.log.comment('Providing useful advice just for you')
>>>         self.log.command('yum update sssd -y')

As you can see, Advice's log has 3 different levels. Debug lines are printed
out with '# DEBUG:' prefix if --verbose had been used. Comment lines utilize
'# ' prefix and command lines are printed raw.

Please note that comments are automatically wrapped after 70 characters.
Use wrapped=False option to force the unwrapped line in the comment.

>>>         self.log.comment("This line should not be wrapped", wrapped=False)

As a result, you can redirect the advice's output directly to a script file.

# ipa-advise sample-advice > script.sh
# ./script.sh
"""


class _AdviceOutput(object):

    def __init__(self):
        self.content = []
        self.prefix = '# '
        self.options = None

    def comment(self, line, wrapped=True):
        if wrapped:
            for wrapped_line in wrap(line, 70):
                self.content.append(self.prefix + wrapped_line)
        else:
            self.content.append(self.prefix + line)

    def debug(self, line):
        if self.options.verbose:
            self.comment('DEBUG: ' + line)

    def command(self, line, indent_spaces=0):
        self.content.append(
            '{}{}'.format(self._format_indent(indent_spaces), line))

    def _format_indent(self, num_spaces):
        return ' ' * num_spaces

    def echo_error(self, error_message, indent_spaces=0):
        self.command(
            self._format_error(error_message), indent_spaces=indent_spaces)

    def _format_error(self, error_message):
        return 'echo "{}" >&2'.format(error_message)

    def exit_on_failed_command(self, command_to_run,
                               error_message_lines, indent_spaces=0):
        self.command(command_to_run, indent_spaces=indent_spaces)
        self.exit_on_predicate(
            '[ "$?" -ne "0" ]',
            error_message_lines,
            indent_spaces=indent_spaces)

    def exit_on_nonroot_euid(self):
        self.exit_on_predicate(
            '[ "$(id -u)" -ne "0" ]',
            ["This script has to be run as root user"]
        )

    def exit_on_predicate(self, predicate, error_message_lines,
                          indent_spaces=0):
        commands_to_run = [
            self._format_error(error_message_line)
            for error_message_line in error_message_lines]

        commands_to_run.append('exit 1')
        self.commands_on_predicate(
            predicate,
            commands_to_run,
            indent_spaces=indent_spaces)

    def commands_on_predicate(self, predicate, commands_to_run_when_true,
                              commands_to_run_when_false=None,
                              indent_spaces=0):
        if_command = 'if {}'.format(predicate)
        self.command(if_command, indent_spaces=indent_spaces)
        self.command('then', indent_spaces=indent_spaces)

        indented_block_spaces = indent_spaces + 2

        for command_to_run_when_true in commands_to_run_when_true:
            self.command(
                command_to_run_when_true, indent_spaces=indented_block_spaces)

        if commands_to_run_when_false is not None:
            self.command("else", indent_spaces=indent_spaces)
            for command_to_run_when_false in commands_to_run_when_false:
                self.command(
                    command_to_run_when_false,
                    indent_spaces=indented_block_spaces)

        self.command('fi', indent_spaces=indent_spaces)


class Advice(Plugin):
    """
    Base class for advices, plugins for ipa-advise.
    """

    options = None
    require_root = False
    description = ''

    def __init__(self, api):
        super(Advice, self).__init__(api)
        self.log = _AdviceOutput()

    def set_options(self, options):
        self.options = options
        self.log.options = options

    def get_info(self):
        """
        This method should be overridden by child Advices.

        Returns a string with instructions.
        """

        raise NotImplementedError


class AdviseAPI(API):
    bases = (Advice,)

    @property
    def packages(self):
        import ipaserver.advise.plugins
        return (ipaserver.advise.plugins,)

advise_api = AdviseAPI()


class IpaAdvise(admintool.AdminTool):
    """
    Admin tool that given systems's configuration provides instructions how to
    configure the systems for various use cases.
    """

    command_name = 'ipa-advise'
    usage = "%prog ADVICE"
    description = "Provides configuration advice for various use cases. To "\
                  "see the list of possible ADVICEs, run ipa-advise without "\
                  "any arguments."

    def __init__(self, options, args):
        super(IpaAdvise, self).__init__(options, args)

    @classmethod
    def add_options(cls, parser):
        super(IpaAdvise, cls).add_options(parser)

    def validate_options(self):
        super(IpaAdvise, self).validate_options(needs_root=False)

        if len(self.args) > 1:
            raise self.option_parser.error("You can only provide one "
                                           "positional argument.")

    def log_success(self):
        pass

    def print_config_list(self):
        self.print_header('List of available advices')

        max_keyword_len = max(
            (len(advice.name) for advice in advise_api.Advice))

        for advice in advise_api.Advice:
            description = getattr(advice, 'description', '')
            keyword = advice.name.replace('_', '-')

            # Compute the number of spaces needed for the table to be aligned
            offset = max_keyword_len - len(keyword)
            prefix = "    {key} {off}: ".format(key=keyword, off=' ' * offset)
            wrapped_description = wrap(description, 80 - len(prefix))

            # Print the first line with the prefix (keyword)
            print(prefix + wrapped_description[0])

            # Print the rest wrapped behind the colon
            for line in wrapped_description[1:]:
                print("{off}{line}".format(off=' ' * len(prefix), line=line))

    def print_header(self, header, print_shell=False):
        header_size = len(header)

        prefix = ''
        if print_shell:
            prefix = '# '
            print('#!/bin/sh')

        # Do not print out empty header
        if header_size > 0:
            print((prefix + '-' * 70))
            for line in wrap(header, 70):
                print((prefix + line))
            print((prefix + '-' * 70))

    def print_advice(self, keyword):
        advice = getattr(advise_api.Advice, keyword, None)

        # Ensure that Configuration class for given --setup option value exists
        if advice is None:
            raise ValidationError(
                name="advice",
                error="No instructions are available for '{con}'. "
                      "See the list of available configuration "
                      "by invoking the ipa-advise command with no argument."
                      .format(con=keyword.replace('_', '-')))

        # Check whether root privileges are needed
        if advice.require_root and os.getegid() != 0:
            raise admintool.ScriptError(
                'Must be root to get advice for {adv}'
                .format(adv=keyword.replace('_', '-')), 1)

        # Print out nicely formatted header
        self.print_header(advice.description, print_shell=True)

        # Set options so that plugin can use verbose/quiet options
        advice.set_options(self.options)

        # Print out the actual advice
        api.Backend.rpcclient.connect()
        advice.get_info()
        api.Backend.rpcclient.disconnect()
        for line in advice.log.content:
            print(line)

    def run(self):
        super(IpaAdvise, self).run()

        api.bootstrap(in_server=False,
                      context='cli',
                      confdir=paths.ETC_IPA)
        api.finalize()
        advise_api.bootstrap(in_server=False,
                             context='cli',
                             confdir=paths.ETC_IPA)
        advise_api.finalize()
        if not self.options.verbose:
            # Do not print connection information by default
            logger_name = r'ipa\.ipalib\.plugins\.rpcclient'
            log_mgr.configure(dict(logger_regexps=[(logger_name, 'warning')]))

        # With no argument, print the list out and exit
        if not self.args:
            self.print_config_list()
            return
        else:
            keyword = self.args[0].replace('-', '_')
            self.print_advice(keyword)