Server Core Development

New in version 1.3.0.

Bcfg2 1.3 added a pluggable server core system so that the server core itself can be easily swapped out to use different technologies. It currently ships with two backends: a builtin core written from scratch using the various server tools in the Python standard library; and an experimental CherryPy based core. This page documents the server core interface so that other cores can be written to take advantage of other technologies, e.g., Tornado or Twisted.

A core implementation needs to:

  • Override Bcfg2.Server.Core.BaseCore._daemonize() to handle daemonization, writing the PID file, and dropping privileges.
  • Override Bcfg2.Server.Core.BaseCore._run() to handle server startup.
  • Override Bcfg2.Server.Core.BaseCore._block() to run the blocking server loop.
  • Call Bcfg2.Server.Core.BaseCore.shutdown() on orderly shutdown.

Nearly all XML-RPC handling is delegated entirely to the core implementation. It needs to:

  • Call Bcfg2.Server.Core.BaseCore.authenticate() to authenticate clients.
  • Handle xmlrpclib.Fault exceptions raised by the exposed XML-RPC methods as appropriate.
  • Dispatch XML-RPC method invocations to the appropriate method, including Plugin RMI. The client address pair (a tuple of remote IP address and remote hostname) must be prepended to the argument list passed to built-in methods (i.e., not to plugin RMI).

Additionally, running and configuring the server is delegated to the core. It needs to honor the configuration options that influence how and where the server runs, including the server location (host and port), listening interfaces, and SSL certificate and key.

Base Core

Core Implementations

Builtin Core

The builtin server core consists of the core implementation (Bcfg2.Server.BuiltinCore.Core) and the XML-RPC server implementation (Bcfg2.SSLServer).

Core

XML-RPC Server

Bcfg2 SSL server used by the builtin server core (Bcfg2.Server.BuiltinCore). This needs to be documented better.

class Bcfg2.SSLServer.SSLServer(listen_all, server_address, RequestHandlerClass, keyfile=None, certfile=None, reqCert=False, ca=None, timeout=None, protocol='xmlrpc/ssl')[source]

Bases: SocketServer.TCPServer, object

TCP server supporting SSL encryption.

Parameters:
  • listen_all (bool) – Listen on all interfaces
  • server_address – Address to bind to the server
  • RequestHandlerClass – Request handler used by TCP server
  • keyfile (string) – Full path to SSL encryption key file
  • certfile (string) – Full path to SSL certificate file
  • reqCert (bool) – Require client to present certificate
  • ca (string) – Full path to SSL CA that signed the key and cert
  • timeout – Timeout for non-blocking request handling
  • protocol (string) – The protocol to serve. Supported values are xmlrpc/ssl and xmlrpc/tlsv1.
class Bcfg2.SSLServer.XMLRPCDispatcher(allow_none, encoding)[source]

Bases: SimpleXMLRPCServer.SimpleXMLRPCDispatcher

An XML-RPC dispatcher.

class Bcfg2.SSLServer.XMLRPCRequestHandler(request, client_address, server)[source]

Bases: SimpleXMLRPCServer.SimpleXMLRPCRequestHandler

XML-RPC request handler.

Adds support for HTTP authentication.

parse_request()[source]

Extends parse_request.

Optionally check HTTP authentication when parsing.

class Bcfg2.SSLServer.XMLRPCServer(listen_all, server_address, RequestHandlerClass=None, keyfile=None, certfile=None, ca=None, protocol='xmlrpc/ssl', timeout=10, logRequests=False, register=True, allow_none=True, encoding=None)[source]

Bases: SocketServer.ThreadingMixIn, Bcfg2.SSLServer.SSLServer, Bcfg2.SSLServer.XMLRPCDispatcher, object

Component XMLRPCServer.

Parameters:
  • listen_all (bool) – Listen on all interfaces
  • server_address – Address to bind to the server
  • RequestHandlerClass – request handler used by TCP server
  • keyfile (string) – Full path to SSL encryption key file
  • certfile (string) – Full path to SSL certificate file
  • ca (string) – Full path to SSL CA that signed the key and cert
  • logRequests (bool) – Log all requests
  • register (bool) – Presence should be reported to service-location
  • allow_none (bool) – Allow None values in XML-RPC
  • encoding – Encoding to use for XML-RPC
ping(*args)[source]

Echo response.

serve_forever()[source]

Serve single requests until (self.serve == False).

shutdown()[source]

Signal that automatic service should stop.

Multiprocessing Core

CherryPy Core