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|
#!/usr/bin/env python
#
# Copyright (C) 2014 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.
import errno
import logging
import json
import os
import sqlite3
import time
import wsgiref.simple_server
import bottle
import cliapp
from flup.server.fcgi import WSGIServer
STATUS_HTML_TEMPLATE = '''
<!DOCTYPE HTML>
<html>
<head>
<title>Lorry Controller status</title>
</head>
<body>
<blockquote>{quote}</blockquote>
<h1>Status of Lorry Controller</h1>
<p>Running queue: {running-queue}.</p>
<p>Free disk space: {disk-free-gib} GiB.</p>
<hr>
<p>Updated: {timestamp}</p>
</body>
</html>
'''
class StateDB(object):
'''A wrapper around raw Sqlite for STATEDB.'''
def __init__(self, filename):
self._filename = filename
self._conn = None
def _open(self):
if self._conn is None:
self._conn = sqlite3.connect(self._filename)
self._initialise_tables()
def _initialise_tables(self):
c = self._conn.cursor()
c.execute('BEGIN TRANSACTION')
c.execute('CREATE TABLE IF NOT EXISTS running_queue (running INT)')
c.execute('INSERT INTO running_queue VALUES (0)')
c.execute('CREATE TABLE IF NOT EXISTS lorries (path TEXT, text TEXT, generated INT)')
self._conn.commit()
def get_running_queue(self):
self._open()
c = self._conn.cursor()
for (running,) in c.execute('SELECT running FROM running_queue'):
return bool(running)
def set_running_queue(self, new_status):
if new_status:
new_value = 1
else:
new_value = 0
self._open()
c = self._conn.cursor()
c.execute('UPDATE running_queue SET running = ?', str(new_value))
self._conn.commit()
def get_lorries(self):
self._open()
c = self._conn.cursor()
return c.execute('SELECT * FROM lorries')
class LorryControllerRoute(object):
'''Base class for Lorry Controller HTTP API routes.
A route is an HTTP request that the Bottle web application
recognises as satisfied by a particular callback. To make it
easier to implement them and get them added automagically to a
Bottle instance, we define the callbacks as subclasses of this
base class.
Subclasses MUST define the attributes ``http_method`` and
``path``, which are given the bottle.Bottle.route method as the
arguments ``method`` and ``path``, respectively.
'''
def __init__(self, app_settings, statedb):
self.app_settings = app_settings
self.statedb = statedb
def run(self, **kwargs):
raise NotImplementedError()
class StatusRenderer(object):
'''Helper class for rendering service status as JSON/HTML'''
def get_status_as_dict(self, statedb, work_directory):
quotes = [
"Never get drunk unless you're willing to pay for it - "
"the next day.",
"I'm giving her all she's got, Captain!",
]
import random
status = {
'quote': '%s' % random.choice(quotes),
'running-queue': statedb.get_running_queue(),
'timestamp': time.strftime('%Y-%m-%d %H:%M:%S'),
}
status.update(self.get_free_disk_space(work_directory))
return status
def render_status_as_html(self, status):
return STATUS_HTML_TEMPLATE.format(**status)
def write_status_as_html(self, status, filename):
html = self.render_status_as_html(status)
with open(filename, 'w') as f:
f.write(html)
def get_free_disk_space(self, dirname):
result = os.statvfs(dirname)
free_bytes = result.f_bavail * result.f_bsize
return {
'disk-free': free_bytes,
'disk-free-mib': free_bytes / 1024**2,
'disk-free-gib': free_bytes / 1024**2,
}
class Status(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/status'
def run(self, **kwargs):
renderer = StatusRenderer()
status = renderer.get_status_as_dict(self.statedb, self.app_settings['statedb'])
renderer.write_status_as_html(status, self.app_settings['status-html'])
return status
class StatusHTML(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/status-html'
def run(self, **kwargs):
renderer = StatusRenderer()
status = renderer.get_status_as_dict(self.statedb, self.app_settings['statedb'])
renderer.write_status_as_html(status, self.app_settings['status-html'])
return renderer.render_status_as_html(status)
class ReadConfiguration(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/read-configuration'
def run(self, **kwargs):
# FIXME: This doesn't update the git repo from upstream, yet.
conf_obj = self.read_config_file()
troves = [x for x in conf_obj if x['type'] == 'trove']
lorries = [x for x in conf_obj if x['type'] == 'lorries']
# FIXME: put the troves and the lorries into STATEDB, but
# don't generate lorries from troves, yet. Don't, in fact,
# scan for local lorries either, yet. Just make sure STATEDB
# has the right tables and columns so that /1.0/list-queue
# will return something reasonable-looking.
return { 'troves': troves, 'lorries': lorries }
def read_config_file(self):
'''Read the configuration file, return as Python object.'''
filename = os.path.join(
self.app_settings['configuration-directory'],
'lorry-controller.conf')
try:
with open(filename) as f:
return json.load(f)
except IOError as e:
if e.errno == errno.ENOENT:
# File doesn't exist. Return an empty configuration.
return []
bottle.abort(500, 'Error reading %s: %s' % (filename, e))
class ListQueue(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/list-queue'
def run(self, **kwargs):
return {
'queue': [row.path for row in self.statedb.get_lorries()],
}
class StartQueue(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/start-queue'
def run(self, **kwargs):
self.statedb.set_running_queue(1)
return 'Queue set to run'
class StopQueue(LorryControllerRoute):
http_method = 'GET'
path = '/1.0/stop-queue'
def run(self, **kwargs):
self.statedb.set_running_queue(0)
return 'Queue set to not run'
class WEBAPP(cliapp.Application):
def add_settings(self):
self.settings.string(
['statedb'],
'use FILE as the state database',
metavar='FILE')
self.settings.string(
['configuration-directory'],
'use DIR as the configuration directory',
metavar='DIR',
default='.')
self.settings.string(
['status-html'],
'write a static HTML page to FILE to describe overall status',
metavar='FILE',
default='/dev/null')
self.settings.boolean(
['wsgi'],
'run in wsgi mode (default is debug mode, for development)')
self.settings.integer(
['debug-port'],
'use PORT in debugging mode '
'(i.e., when not running under WSGI); '
'note that using this to non-zero disables --debug-port-file',
metavar='PORT',
default=0)
self.settings.string(
['debug-port-file'],
'write listening port to FILE when in debug mode '
'(i.e., not running under WSGI)',
metavar='FILE',
default='webapp.port')
self.settings.string(
['debug-host'],
'listen on HOST when in debug mode (i.e., not running under WSGI)',
metavar='HOST',
default='0.0.0.0')
def find_routes(self):
'''Return all classes that are API routes.
This is a generator.
'''
# This is a bit tricky and magic. globals() returns a dict
# that contains all objects in the global namespace. We
# iterate over the objects and pick the ones that are
# subclasses of our superclass (no duck typing here), but ARE
# NOT the superclass itself.
for x in globals().values():
is_route = (
type(x) == type and # it must be class, for issubclass
issubclass(x, LorryControllerRoute) and
x != LorryControllerRoute)
if is_route:
yield x
def process_args(self, args):
self.settings.require('statedb')
statedb = StateDB(self.settings['statedb'])
webapp = bottle.Bottle()
for route_class in self.find_routes():
route = route_class(self.settings, statedb)
webapp.route(
path=route.path,
method=route.http_method,
callback=route.run)
logging.info('Starting server')
if self.settings['wsgi']:
self.run_wsgi_server(webapp)
else:
self.run_debug_server(webapp)
def run_wsgi_server(self, webapp):
WSGIServer(webapp).run()
def run_debug_server(self, webapp):
if self.settings['debug-port']:
self.run_debug_server_on_given_port(webapp)
else:
self.run_debug_server_on_random_port(webapp)
def run_debug_server_on_given_port(self, webapp):
bottle.run(
webapp,
host=self.settings['debug-host'],
port=self.settings['debug-port'],
quiet=True,
debug=True)
def run_debug_server_on_random_port(self, webapp):
server_port_file = self.settings['debug-port-file']
class DebugServer(wsgiref.simple_server.WSGIServer):
'''WSGI-like server that uses an ephemeral port.
Rather than use a specified port, or default, the
DebugServer connects to an ephemeral port and writes
its number to debug-port-file, so a non-racy temporary
port can be used.
'''
def __init__(self, (host, port), *args, **kwargs):
wsgiref.simple_server.WSGIServer.__init__(
self, (host, 0), *args, **kwargs)
with open(server_port_file, 'w') as f:
f.write(str(self.server_port) + '\n')
bottle.run(
webapp,
host=self.settings['debug-host'],
server_class=DebugServer,
quiet=True,
debug=True)
WEBAPP().run()
|
