Monolithic Config Files Considered Harmful^WAwkward to Manage
This came up in conversation with a developer at the Google OpenSource Jam so I thought I’d mention it while it is fresh in my mind (update: at which point I forgot to move it to the published directory. Doh). Breaking up config files isn’t done just to annoy people, it’s done to make automated and mass management easier.
A solid practical example is the Debian Apache configs. Historically most distros (and too many current ones) used a single config file for Apache. While this made interactive editing easier by presenting all the options in a single place (and in a sensible order) it made it very hard for the package management software (or automation aficionados) to add a module or virtual host without some hairy scripting. Removing settings when a package is removed or updating a small chunk of the config in an upgrade is even more painful; as for preserving local changes - haha.
By breaking the config out in to a number of files / directories and combining them at run time it makes the addition of a new vhost or module config just a file drop and possibly a symlink (often used if the configs are order dependent). This is easier for third party packages to perform and makes provisioning of additional apps a lot easier.
So what’s the main downside? Debugging. An “Error on line 50” is harder to track when line 50 could be in one of twelve files. But with a little forethought debug messages can be updated to show all the useful information. So next time you’re writing an app of many parts please spare a thought for the sysadmins and make it easily manageable.