path: root/scripts/distbuild

#!/usr/bin/env python
# Copyright (C) 2015  Codethink Limited
#
# 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; version 2 of the License.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

'''Run a local instance of a Morph distributed build network.

To use:

    scripts/distbuild run

If you want more info on what is going on, try:

    scripts/distbuild run --log=/dev/stdout

All distbuild subprocesses will be shut down on TERM signal or if any of them
crash.

Logs and build artifacts will be stored in a newly created temporary directory.
You can specify a different location with the --datadir argument. The directory
will not be deleted when the process exits.

'''


DISTBUILD_HELPER = 'distbuild-helper'
MORPH = 'morph'
MORPH_CACHE_SERVER = 'morph-cache-server'


import os
import select
import subprocess
import tempfile
import time
from logging import debug, info

import cliapp


def subdir(workdir, *path_components):
    '''Create a subdirectory and return the path to it.'''
    path = os.path.join(workdir, *path_components)
    os.makedirs(path)
    return path


class Process(subprocess.Popen):
    '''A running subprocess.'''

    def __init__(self, name, argv, settings, **kwargs):
        '''Start a new subprocess, using subprocess.Popen.

        The 'name' parameter is only used internally.

        The 'argv' parameter specifies the commandline to be run. The
        'settings' dict will be formatted as long-form commandline switches and
        added to 'argv'.

        '''
        self.name = name
        self.argv = argv
        self.settings = settings

        full_argv = argv + self._format_settings(settings)
        info('%s commandline: %s' % (name, ' '.join(full_argv)))
        super(Process, self).__init__(full_argv, **kwargs)
        info('%s process ID: %s' % (name, self.pid))

    def _format_settings(self, arg_dict):
        def as_string(key, value):
            if value is True:
                return '--%s' % key
            elif value is False:
                return ''
            else:
                return '--%s=%s' % (key, value)
        return [as_string(k, v) for k, v in arg_dict.iteritems()]


class MorphProcess(Process):
    '''A running instance of Morph, morph-cache-server or distbuild-helper.'''

    def __init__(self, name, argv, settings, log_path=None, **kwargs):
        '''Start an instance of Morph, morph-cache-server or distbuild-helper.

        The logs will be sent to a file called '$log_path/morph-$name.log', if
        log_path is passed.

        '''
        if log_path:
            settings['log'] = os.path.join(log_path, 'morph-%s.log' % name)
        settings['no-default-config'] = True

        super(MorphProcess, self).__init__(name, argv, settings, **kwargs)


class MorphListenerProcess(MorphProcess):
    '''A running instance of a Morph or morph-cache-server daemon process.'''

    def __init__(self, name, port_names, argv, settings, **kwargs):
        '''Start and wait for an instance of Morph or morph-cache-server.

        Using --port-file arguments, the constructor will wait for each port
        listed in 'port_names' to become ready before returning. The subprocess
        will pick a random available port number for each port. The numbers
        be accessible as attributes on this class.

        For example, if you pass port_names=['worker-daemon-port'], the
        subprocess will receive two extra commandline arguments:
            --worker-daemon-port=0 and --worker-daemon-port-file=xxx

        Once the process starts, self.worker_daemon_port will contain the
        number of the port that it is listening on.

        '''
        for port_name in port_names:
            self._setup_port_fifo(port_name, settings)

        super(MorphListenerProcess, self).__init__(
            name, argv, settings, **kwargs)

        for port_name in port_names:
            port_number = self._read_port_fifo(port_name, settings)
            info('%s: %s port is %s' % (name, port_name, port_number))

            port_attr = port_name.replace('-', '_')
            setattr(self, port_attr, port_number)

    def _setup_port_fifo(self, port_name, settings):
        tempdir = tempfile.mkdtemp()
        port_file = os.path.join(tempdir, '%s.port' % (port_name))
        os.mkfifo(port_file)

        # Note that Python passes dicts by reference, so this modifies the
        # dict that was passed in.
        settings['%s' % port_name] = 0
        settings['%s-file' % port_name] = port_file

    def _read_port_fifo(self,  port_name, settings):
        port_file = settings['%s-file' % port_name]

        debug('Read: %s' % port_file)
        with open(port_file, 'r') as f:
            # The readline() call will block until a line of data is written.
            # The process we are starting should only write out the port number
            # once the process is listening on that port. Thus, we block until
            # the process is ready, which is very important for avoiding races.
            port_number = int(f.readline())

        os.unlink(port_file)
        os.rmdir(os.path.dirname(port_file))

        return port_number


class MorphCacheServerProcess(MorphListenerProcess):
    '''A morph-cache-server process.'''

    def __init__(self, name, cache_path, log_path=None, enable_writes=False):
        '''Start a morph-cache-server process.'''

        ports = ['port']
        argv = [MORPH_CACHE_SERVER]

        settings = {
            'artifact-dir': subdir(cache_path, 'artifacts'),
            'enable-writes': enable_writes,
            'no-fcgi': True,
            'repo-dir': subdir(cache_path, 'gits'),
        }

        super(MorphCacheServerProcess, self).__init__(
            name, ports, argv, settings, log_path=log_path,
            stderr=subprocess.PIPE)


class MorphWorkerDaemonProcess(MorphListenerProcess):
    '''A `morph worker-daemon` process.'''
    def __init__(self, name, cache_server, log_path=None):
        '''Start a `morph worker-daemon` instance.'''

        ports = ['worker-daemon-port']
        argv = [MORPH, 'worker-daemon']

        settings = {
            'artifact-cache-server': 'http://localhost:%s' % cache_server.port,
        }

        super(MorphWorkerDaemonProcess, self).__init__(
            name, ports, argv, settings, log_path=log_path)


class ProcessMonitor(object):
    '''A tool for managing a bunch of subprocesses.'''

    def __init__(self):
        self.process = {}

    def watch(self, process):
        '''Start monitoring a running process.'''
        self.process[process.name] = process

    def check_all(self):
        '''Check all processes are running.'''
        for name, p in self.process.iteritems():
            if p.poll() != None:
                raise Exception(
                    '%s: exited with code %s' % (name, p.returncode))

    def terminate_all(self):
        '''Send TERM signal to all active subprocesses.'''
        for p in self.process.itervalues():
            if p.poll() == None:
                p.terminate()
                info('Waiting for process %i' % p.pid)
                p.wait()


class DistbuildTestHarness(cliapp.Application):
    '''Harness for running a distbuild network on a single machine.'''

    def __init__(self):
        super(DistbuildTestHarness, self).__init__()

        self.process_monitor = ProcessMonitor()

    def add_settings(self):
        self.settings.string(
            ['datadir'],
            'location to cache gits and artifacts, and write log files')
        self.settings.string(
            ['morph-instance'],
            'Path to Morph program that will run worker-build and '
            'serialise-artifact commands')
        self.settings.string(
            ['port-file'],
            'write port used by initiator to FILE, when ready')
        self.settings.integer(
            ['workers'],
            'number of workers to start',
            default=4)

    def cmd_run(self, args):
        '''Run a distbuild network.'''

        try:
            datadir = self.settings['datadir'] or tempfile.mkdtemp()

            worker_cache, shared_cache = self.start_cache_servers(datadir)

            controller = self.start_distbuild_network(
                datadir, worker_cache, shared_cache,
                morph_instance=self.settings['morph-instance'],
                n_workers=self.settings['workers'])

            if self.settings['port-file']:
                with open(self.settings['port-file'], 'w') as f:
                    f.write('%s' % controller.controller_initiator_port)

            print('Distbuild controller listening on port %i' %
                  controller.controller_initiator_port)
            print('Data in %s' % datadir)

            print('\nTo use: morph distbuild '
                  '--controller-initiator-address=localhost '
                  '--controller-initiator-port=%i FILE' %
                  controller.controller_initiator_port)

            # Run until we get a TERM signal.
            while True:
                select.select([], [], [], 1)
                self.process_monitor.check_all()
        finally:
            self.process_monitor.terminate_all()

    def start_cache_servers(self, workdir):
        '''Start necessary artifact cache servers.

        There needs to be a shared artifact cache server. In a normal distbuild
        setup this is part of the Trove system.

        There is a separate cache server for all the workers. In a real
        distbuild setup, each worker machine runs its own instance of
        morph-cache-server. The controller uses the same port number for all
        workers so in this test harness all workers will have to share one
        cache-server process.

        It's not possible to use a single cache server process at present,
        because when the /fetch method of the shared cache server is called, it
        will break because it can't fetch stuff from itself.

        '''
        worker_cache = MorphCacheServerProcess(
            name='worker-cache-server',
            cache_path=subdir(workdir, 'worker-cache'),
            log_path=workdir,
            enable_writes=False)
        self.process_monitor.watch(worker_cache)

        shared_cache = MorphCacheServerProcess(
            name='shared-cache-server',
            cache_path=subdir(workdir, 'shared-cache'),
            log_path=workdir,
            enable_writes=True)
        self.process_monitor.watch(shared_cache)

        return worker_cache, shared_cache

    def start_distbuild_network(self, workdir, worker_cache, shared_cache,
                                morph_instance=None, n_workers=4):
        '''Start Morph distbuild daemons and helper processes.

        This starts a `morph controller-daemon` process, and one or more `morph
        worker-daemon` processes. It also starts the helper process that these
        need. It returns the controller process, which is the one you need to
        talk to if you want to start a build.

        '''

        if not morph_instance:
            # Create a wrapper script for the Morph that will be used to run
            # `serialise-artifact` and `worker-build` commands, so we can pass
            # it the commandline arguments it neds.
            worker_morph = os.path.join(workdir, 'worker-morph')

            with open(worker_morph, 'w') as f:
                cache_dir = os.path.join(workdir, 'worker-cache')
                log = os.path.join(workdir, 'morph.log')
                f.write('#!/bin/sh\n')
                f.write('%s --cachedir=%s --log=%s $@\n' % (
                    MORPH, cache_dir, log))

            os.chmod(worker_morph, 0755)
            morph_instance = worker_morph

        workers = []
        for n in range(0, n_workers):
            worker = MorphWorkerDaemonProcess(
                name='worker-%i' % n,
                cache_server=worker_cache,
                log_path=workdir)
            self.process_monitor.watch(worker)

            workers.append('localhost:%i' % worker.worker_daemon_port)

            worker_helper = MorphProcess(
                name='worker-%i-helper' % n,
                argv=[DISTBUILD_HELPER],
                settings={
                    'parent-port': worker.worker_daemon_port,
                },
                log_path=workdir
            )
            self.process_monitor.watch(worker_helper)

        shared_cache_url = 'http://localhost:%s' % shared_cache.port

        controller = MorphListenerProcess(
            name='controller',
            # Order is significant -- helper-port must be first!
            port_names=['controller-helper-port', 'controller-initiator-port'],
            argv=[MORPH, 'controller-daemon'],
            settings={
                'controller-initiator-address': 'localhost',
                'morph-instance': morph_instance,
                'worker': ','.join(workers),
                'worker-cache-server-port': worker_cache.port,
                'writeable-cache-server': shared_cache_url,
            },
            log_path=workdir)
        self.process_monitor.watch(controller)

        controller_helper = MorphProcess(
            name='controller-helper',
            argv=[DISTBUILD_HELPER],
            settings={
                'parent-port': controller.controller_helper_port,
            },
            log_path=workdir
        )
        self.process_monitor.watch(controller_helper)

        # Need to wait for controller-helper to connect to controller.
        time.sleep(0.1)
        self.process_monitor.check_all()

        return controller


DistbuildTestHarness().run()