From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Nelson Subject: Re: The fundamental evil of "magic" in computing systems -> Was: mon daemon makes authentication side effects on startup Date: Thu, 7 Apr 2016 15:40:28 -0500 Message-ID: <5706C5BC.4090006@redhat.com> References: <5703A7FF.2090002@suse.com> <5704C76C.2050408@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34043 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757331AbcDGUkc (ORCPT ); Thu, 7 Apr 2016 16:40:32 -0400 In-Reply-To: <5704C76C.2050408@suse.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Owen Synge , Gregory Farnum Cc: Ceph Development On 04/06/2016 03:23 AM, Owen Synge wrote: > Dear Greg and others, > > Thankyou for your very helpful email, as it completely misses my point, > and that illustrate why this point is so important to be addressed. > > I am sure Greg has a deep understanding of this area. But I am pleased > Greg missed my points from 0-9, Greg's assumption that it is lack of > understanding on my part (which I am sure is common), clearly > illustrates where this "magic" of the side effect of starting a mon > demon becomes becomes "dark magic". > > If you object to "magic" and "dark magic" in this email please > substitute them with "side effect" and "negative consequences of side > effects" respectively, and you get a more serious reply :) > FWIW, I wanted to chime in and say that anything we can do to generally reduce instances of "dark magic" like this would be fantastic. Back when mkcephfs was retired a couple of years ago I had to decide what I should replace it with in CBT. Ultimately it was concern over issues like this that lead me to utilize the underlying key/mon/osd creation tools directly. Your point about confusion is totally valid. I use ceph-authtool and had only a vague idea that ceph-create-keys even existed (and certainly didn't realize the behavior your describing). I create ceph clusters (using CBT) to test performance pretty much daily! Looking at the documentation, it's pretty easy to miss what's going on: http://docs.ceph.com/docs/master/man/8/ceph-create-keys/ ceph-authtool is a little better documented: http://docs.ceph.com/docs/hammer/man/8/ceph-authtool/ It *is* scary when software behaves in mysterious ways. It doesn't invoke trust and it's not the kind of first impression to make with already paranoid sysadmins (Being a paranoid ex-sysadmin myself). I think our heart was in the right place to try to reduce the number of steps required in ceph-deploy, but it can't come at the expense of introducing ambiguity and complexity like this. Anyway, that's my 2C. Mark