Using mercurial for configuration files version control

[Vadym Chepkov]

On Nov 25, 2010, at 9:44 AM, Jouni Airaksinen wrote:

> In one project I had setup for application specific cronjob configurations and the jobs were different for each server in the cluster (not equally balanced system and some services were fixed to certain servers). It was solved so that in the repository had separate files for each server and each server was just configured to use those certain files (either directly or through symlinks). Then each server cloned/pulled changes from one main repository. Whole thing was orchestrated with Capistrano. 
> 

But this would imply I have to maintain many instances of exactly the same file except 2/3 line and don't forget to apply the same changes in those copies. :(
Whatever depends on "not forget" is bound for failure in my opinion.

Vadym

> 
> 
> From:        FELD Boris <lothiraldan at gmail.com> 
> To:        Vadym Chepkov <vchepkov at gmail.com> 
> Cc:        mercurial at selenic.com 
> Date:        25.11.2010 16.19 
> Subject:        Re: Using mercurial for configuration files version control 
> Sent by:        mercurial-bounces at selenic.com 
> 
> 
> 
> Hi, 
> 
> I am not sure to understand all of your problem, but i can give you my point of view. 
> 
> The situation you describe is a common problem with dcvs where every developer must adapt configuration files to his system. 
> 
> The solution is quite simple, you just track a template version of your configuration file. 
> In your case, the  template version could be very short : 
> hostname="" 
> ifconfig_bce0="inet 192.168.17. netmask 255.255.255.0" 
> 
> You named this file /etc/rc.conf.tpl and track this file into mercurial. Then for each node, you create a local file based on this template file. 
> 
> For the second problem you describe, it's normal. If i resume your process, on each node : 
> - You pull from "master" (rev 1) 
> - You modify /etc/rc.conf and commit locally (rev 2) 
> - After a modification on "master" repository, you pull from "master" (rev 3) 
> 
> The problem is when you commit locally your changes on /etc/rc.conf, master repository not contains this changeset and when you try to update, mercurial does not know to which repository to update. 
> To visualise this situation, go to your local repository, type this command "hg serve -v". Then launch your webbrowser and go to this adress :  "ht tp://You r_node_adress:8000/graph" 
> 
> I'm not sure i was clear, i hope it help you 
> 
> -- 
> FELD Boris
> Sent with Sparrow 
> On jeudi 25 novembre 2010 at 14:54, Vadym Chepkov wrote:
> 
> Hi,
> 
> I am trying to use mercurial for tracking / populating configuration files and I am facing some obstacles I need help to overcome.
> The technique works quite well with a standalone host. I usually do this:
> 
> cd /etc
> hg init 
> cat > .hgignore <<EOF
> syntax: glob
> *
> EOF
> hg add .hgignore
> hg commit -m "Starting with empty set"
> 
> Then I add all files I modify to the repository and track changes that were made.
> 
> Now I want to use this repository to populate configuration among members of a cluster, because all changes that are made almost always absolutely the same on all nodes.
> 
> First challenge - I am not able to clone remote repository into an existing /etc directory on a second node - there is no such thing as "force", at least I wasn't able to find it.
> So, instead, I did hg init on the second node and did hg pull ssh://master//etc/ . This concerns me a bit, because the repositories don't have a common "parent", don't know how essential this is.
> Anyway, all works well until I added /etc/rc.conf into repository. This is one of those seldom cases where some lines in the file are different on every node.
> for example, on master node
> 
> hostname="master"
> ifconfig_bce0="inet 192.168.17.254 netmask 255.255.255.0"
> 
> on slave:
> hostname="slave"
> ifconfig_bce0="inet 192.168.17.253 netmask 255.255.255.0"
> 
> After I pulled form master's mercurial, as expected, overwrote local rc.conf, so I modified those few lines in it and committed these changes locally, without any future intents to push any local changes back to master.
> 
> And now I have a second challenge. Now every time I pull from the master it creates a new head I have to merge and commit, even changes that has nothing to do with rc.conf, but even then, if I just add one single line to the end of master's rc.conf, I would expect mercurial to be able to duplicate this simple delta without do ing any manual merges.
> 
> I realize not many use mercurial this way, so I had to describe the task in details, but I don't think I am trying to do something unreasonable and would appreciate your advice to how to do it properly.
> 
> Thank you,
> Vadym Chepkov
> 
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