DPythOS 0.0 released

Luke Kenneth Casson Leighton lkcl@samba-tng.org
Mon, 13 May 2002 20:49:56 +0000

[This one's the project that caused all the hassle back
 when Python 2.0 was in beta :) ]


	DPythOS - Data, or Distributed, Python OS.




	DPythOS provides the means to monitor and manage
	network hosts and services.

	Unlike most monitoring packages, DPythOS provides
	administrators with a way to _correct_ problems
	if they occur, and to notify them if that also




	DPythOS scripts are run in restricted and minimally
	extended python environment.  Scripts can be run or
	scheduled from the command-line, and also scheduled
	from a [very basic!] HTML interface.

	Scheduled scripts are run priority-based on a per-host
	basis, with the maximum number of simultaneous scripts
	being run by the monitor daemon (monitord.py) limited
	in a config file option.
	DPythOS runs [at present] a telnet, or ssh, or HTTP
	connection to a remote host.  Data can be sent
	down the connection, and the results received and
	acted on.  

Implementation Fun And Games:

	people really interested in what kind of weird uhh...
	stuff... can be done with Python will be intrigued to
	know that DPythOS does the following:

	-	uses the newly introduced BaseServer in SocketServer.py
		to create a SQL database server "thing".

		basically, it locks, polls entries in the script
		scheduler table, reads the entry (which includes
		the script name, host name and priority),
		actions the script, removes the entry, unlocks.

		this was the whole reason why i submitted the
		BaseServer patches, but couldn't release the code
		that _used_ it, at the time.

	-	overloads ihooks such that "import" first checks
		whether the script being imported is in the SQL
		database (!!! :) and provides the functions from
		the scripts table instead of off of the filesystem.
		[cool :)]

		in this way, common libraries can be developed
		and managed from the central database.  for example,
		the "loginlib" SQL script loads the login username
		and password for the target host, and actions the
		default login method (telnet or ssh) in order to
		provide a command-prompt by which the host may be

		all this is done under database control.  cool, huh?

	-	overloads rlcompleter such that in script interactive
		mode (suitable for use as a superuser login shell,
		amongst other things) host names, script names and
		DPythOS functions have readline tab completion


	-	uses a TelnetBase class (which wasn't suitable for
		release in Python2) to provide Popen3Telnet (via
		which ssh is then accessed), HTTPTelnet, and anything
		else you fancy to add.

		basically, the write and the read_until, read_some
		functionality of Telnet was _way_ too good to miss
		up on for ssh, http and popen3 wrapping.

		so i didn't [miss it, that is].

	-	Database abstraction.  i wrote a SQL database
		abstraction system that constructs SQL statements
		in sections.  if you hate views, or if your
		SQL server doesn't support it, the abstraction
		layer is a good way to construct complex SQL rules 
		and joins without duplicating loads of text.

		also, bundled with the distro is pyxsqmsll2000,
		which is a stupid name for a Microsoft SQL 2000
		XML access client.  SQL 2000 has an XML interface
		which you can enable: pyxsqmsll2000 can send SQL
		statements via HTTP and actually understands the
		results that come back.



-	all versions of ssh are non-interactive with respect to
	password input.  i had to patch open-ssh to accept
	passwords on the command-line (ssh password:user@host).

-	last time i checked, there were locking issues with the
	version of MySQL i was using (2001).  the same table
	in one of the databases is opened _three_ times under
	different names, one with write access and the other two
	aliases with read access.