\section{The Evolution of Finger: configuration and packaging of the finger service\label{doc/howto/tutorial/configuration.xhtml}}


\subsection{Introduction}


 This is the eleventh part of the Twisted tutorial \textit{Twisted from Scratch, or The Evolution of Finger}\loreref{doc/howto/tutorial/index.xhtml}.

In this part, we make it easier for non-programmers to configure a finger server, and show how to package it in the .deb and RPM package formats.

\subsection{Plugins}


So far, the user had to be somewhat of a programmer to be able to configure stuff. Maybe we can eliminate even that? Move old code to finger/\_\_init\_\_.py and...

 Full source code for finger module here: \begin{verbatim}
# finger.py module

from twisted.application import internet, service, strports
from twisted.internet import protocol, reactor, defer
from twisted.protocols import basic, irc
from twisted.python import components
from twisted.web import resource, server, static, xmlrpc, microdom
from twisted.web.woven import page, model, interfaces
from twisted.spread import pb
from OpenSSL import SSL
import cgi

class IFingerService(components.Interface):

    def getUser(self, user):
        """Return a deferred returning a string"""

    def getUsers(self):
        """Return a deferred returning a list of strings"""

class IFingerSetterService(components.Interface):

    def setUser(self, user, status):
        """Set the user's status to something"""

def catchError(err):
    return "Internal error in server"

class FingerProtocol(basic.LineReceiver):

    def lineReceived(self, user):
        d = self.factory.getUser(user)
        d.addErrback(catchError)
        def writeValue(value):
            self.transport.write(value+'\n')
            self.transport.loseConnection()
        d.addCallback(writeValue)


class IFingerFactory(components.Interface):

    def getUser(self, user):
        """Return a deferred returning a string"""

    def buildProtocol(self, addr):
        """Return a protocol returning a string"""


class FingerFactoryFromService(protocol.ServerFactory):
    __implements__ = protocol.ServerFactory.__implements__, IFingerFactory

    protocol = FingerProtocol

    def __init__(self, service):
        self.service = service

    def getUser(self, user):
        return self.service.getUser(user)

components.registerAdapter(FingerFactoryFromService,
                           IFingerService,
                           IFingerFactory)

class FingerSetterProtocol(basic.LineReceiver):

    def connectionMade(self):
        self.lines = []

    def lineReceived(self, line):
        self.lines.append(line)

    def connectionLost(self, reason):
        if len(self.lines) == 2:
            self.factory.setUser(*self.lines)


class IFingerSetterFactory(components.Interface):

    def setUser(self, user, status):
        """Return a deferred returning a string"""

    def buildProtocol(self, addr):
        """Return a protocol returning a string"""


class FingerSetterFactoryFromService(protocol.ServerFactory):

    __implements__ = protocol.ServerFactory.__implements__,IFingerSetterFactory

    protocol = FingerSetterProtocol

    def __init__(self, service):
        self.service = service

    def setUser(self, user, status):
        self.service.setUser(user, status)


components.registerAdapter(FingerSetterFactoryFromService,
                           IFingerSetterService,
                           IFingerSetterFactory)

class IRCReplyBot(irc.IRCClient):

    def connectionMade(self):
        self.nickname = self.factory.nickname
        irc.IRCClient.connectionMade(self)

    def privmsg(self, user, channel, msg):
        user = user.split('!')[0]
        if self.nickname.lower() == channel.lower():
            d = self.factory.getUser(msg)
            d.addErrback(catchError)
            d.addCallback(lambda m: "Status of %s: %s" % (msg, m))
            d.addCallback(lambda m: self.msg(user, m))


class IIRCClientFactory(components.Interface):

    """
    @ivar nickname
    """

    def getUser(self, user):
        """Return a deferred returning a string"""

    def buildProtocol(self, addr):
        """Return a protocol"""


class IRCClientFactoryFromService(protocol.ClientFactory):

    __implements__ = protocol.ClientFactory.__implements__, IIRCClientFactory

    protocol = IRCReplyBot
    nickname = None

    def __init__(self, service):
        self.service = service

    def getUser(self, user):
        return self.service.getUser(user)

components.registerAdapter(IRCClientFactoryFromService,
                           IFingerService,
                           IIRCClientFactory)

class UsersModel(model.MethodModel):

    def initialize(self, *args, **kwargs):
        self.service=args[0]

    def wmfactory_users(self, request):
        return self.service.getUsers()

components.registerAdapter(UsersModel, IFingerService, interfaces.IModel)

class UserStatusTree(page.Page):

    template = """<html><head><title>Users</title></head><body>
    <h1>Users</h1>
    <ul model="users" view="List">
    <li pattern="listItem"><a view="Anchor" /></li>
    </ul></body></html>"""

    def initialize(self, *args, **kwargs):
        self.service=args[0]

    def getDynamicChild(self, path, request):
        return UserStatus(user=path, service=self.service)

    def wchild_RPC2 (self, request):
        return UserStatusXR(self.service)

components.registerAdapter(UserStatusTree, IFingerService, resource.IResource)


class UserStatus(page.Page):

    template='''<html><head><title view="Text" model="user"/></head>
    <body><h1 view="Text" model="user"/>
    <p model="status" view="Text" />
    </body></html>'''

    def initialize(self, **kwargs):
        self.user = kwargs['user']
        self.service = kwargs['service']

    def wmfactory_user(self, request):
        return self.user

    def wmfactory_status(self, request):
        return self.service.getUser(self.user)


class UserStatusXR(xmlrpc.XMLRPC):

    def __init__(self, service):
        xmlrpc.XMLRPC.__init__(self)
        self.service = service

    def xmlrpc_getUser(self, user):
        return self.service.getUser(user)

    def xmlrpc_getUsers(self):
        return self.service.getUsers()


class IPerspectiveFinger(components.Interface):

    def remote_getUser(self, username):
        """return a user's status"""

    def remote_getUsers(self):
        """return a user's status"""

class PerspectiveFingerFromService(pb.Root):

    __implements__ = pb.Root.__implements__, IPerspectiveFinger

    def __init__(self, service):
        self.service = service

    def remote_getUser(self, username):
        return self.service.getUser(username)

    def remote_getUsers(self):
        return self.service.getUsers()

components.registerAdapter(PerspectiveFingerFromService,
                           IFingerService,
                           IPerspectiveFinger)


class FingerService(service.Service):

    __implements__ = service.Service.__implements__, IFingerService

    def __init__(self, filename):
        self.filename = filename
        self._read()

    def _read(self):
        self.users = {}
        for line in file(self.filename):
            user, status = line.split(':', 1)
            user = user.strip()
            status = status.strip()
            self.users[user] = status
        self.call = reactor.callLater(30, self._read)

    def getUser(self, user):
        return defer.succeed(self.users.get(user, "No such user"))

    def getUsers(self):
        return defer.succeed(self.users.keys())


class ServerContextFactory:

    def getContext(self):
        """Create an SSL context.

        This is a sample implementation that loads a certificate from a file
        called 'server.pem'."""
        ctx = SSL.Context(SSL.SSLv23_METHOD)
        ctx.use_certificate_file('server.pem')
        ctx.use_privatekey_file('server.pem')
        return ctx




# Easy configuration

def makeService(config):
    # finger on port 79
    s = service.MultiService()
    f = FingerService(config['file'])
    h = internet.TCPServer(79, IFingerFactory(f))
    h.setServiceParent(s)


    # website on port 8000
    r = resource.IResource(f)
    r.templateDirectory = config['templates']
    site = server.Site(r)
    j = internet.TCPServer(8000, site)
    j.setServiceParent(s)

    # ssl on port 443
#    if config.get('ssl'):
#        k = internet.SSLServer(443, site, ServerContextFactory())
#        k.setServiceParent(s)

    # irc fingerbot
    if config.has_key('ircnick'):
        i = IIRCClientFactory(f)
        i.nickname = config['ircnick']
        ircserver = config['ircserver']
        b = internet.TCPClient(ircserver, 6667, i)
        b.setServiceParent(s)

    # Pespective Broker on port 8889
    if config.has_key('pbport'):
        m = internet.TCPServer(
            int(config['pbport']),
            pb.PBServerFactory(IPerspectiveFinger(f)))
        m.setServiceParent(s)

    return s
\end{verbatim}\parbox[b]{\linewidth}{\begin{center}finger module --- \begin{em}finger.py\end{em}\end{center}}\begin{verbatim}
# finger/tap.py
from twisted.application import internet, service
from twisted.internet import interfaces
from twisted.python import usage
import finger

class Options(usage.Options):

    optParameters = [
        ['file', 'f', '/etc/users'],
        ['templates', 't', '/usr/share/finger/templates'],
        ['ircnick', 'n', 'fingerbot'],
        ['ircserver', None, 'irc.freenode.net'],
        ['pbport', 'p', 8889],
        ]

    optFlags = [['ssl', 's']]

def makeService(config):
    return finger.makeService(config)
\end{verbatim}\parbox[b]{\linewidth}{\begin{center}finger/tap.py --- \begin{em}tap.py\end{em}\end{center}}

And register it all:\begin{verbatim}
#finger/plugins.tml
register('finger', 'finger.tap',
	description='Build a finger server tap',
	type='tap', tapname='finger')
\end{verbatim}\parbox[b]{\linewidth}{\begin{center}finger/plugins.tml --- \begin{em}plugins.tml\end{em}\end{center}}

And now, the following works\begin{verbatim}
% mktap finger --file=/etc/users --ircnick=fingerbot
% sudo twistd -nf finger.tap
\end{verbatim}


\subsection{OS Integration}


If we already have the ``finger'' package installed in PYTHONPATH (e.g.  we added it to site-packages), we can achieve easy integration:

\subsubsection{Debian}
\begin{verbatim}
% tap2deb --unsigned -m "Foo <foo@example.com>" --type=python finger.tac
% sudo dpkg -i .build/*.deb
\end{verbatim}


\subsubsection{Red Hat / Mandrake}
\begin{verbatim}
% tap2rpm --type=python finger.tac #[maybe other options needed]
% sudo rpm -i .build/*.rpm
\end{verbatim}


Will properly register the tap/tac, init.d scripts, etc. for the given file.

If it doesn't work on your favorite OS: patches accepted!