|Think about Loose Coupling|
Re^4: What is YOUR Development Process?by swiftone (Curate)
|on Nov 08, 2005 at 15:45 UTC||Need Help??|
you're trying to solve a very difficult problem
Possibly. Right now my process is bad, so I'm looking at what others are doing to see what is better. I'd LIKE to resolve my dependency issue between components, but that's not my orverall goal: I just want a better, more reliable process.
Put everything in version control and have one release cycle where you release everything.
Help me out with some details here.
Let's say I write a CRUD application. I can put the app modules, the backend CDBI modules, the templates, and the instance script into version control, and tag them all with "app Foo". I can then check them out on the production server. (In truth, I'll be looking up how to tag in subversion first :) )
Later, someone (possibly me, possibly not) handles a request for another CRUD app, with a couple of new features. That means tweaking the original app module, and writing a new instance script, and creating one or two new templates, but using a bunch of the original templates (actually, we use a inheriting tree hierarchy, so any templates not replaced are inherited, but not copied. (if /path/to/this/app/templates/Foo.tmpl doesn't exist, it will look in /path/to/this/app, and /path/to/this, and so forth))
How do we mark that? The original app should now use the newer version of the app module. On the production machine, only one copy of the app module will exist. All the templates will exist, but the new app should use any templates from the other app that aren't overridden, so I can't just snapshot at this moment.
Also, how do we ensure that the next guy to come along can check out HIS upgrade on the production server without running into problems that the files _I_ checked out are owned by me?
Make sure that every production machine has the same versions of everything.
How do you do that? Previously we've tried running a local mini-CPAN, and loading all servers off of that, currently my sysadmin is packing all perl modules into rpms(ick) that exist on our local rpm repository that all our servesr upgrade from. I've seen someone else here recommend mounting /usr/local/ so that everything IS the same on all the servers. This is definitely a solvable problem, I'm just curious how YOU do it.
The motto here is "work in reversible and independent changes". That way each change can be tested and rolled out. If anything breaks then you know what it was and can easily roll it back.
I like the motto, I'm still trying to figure out HOW to do it. When one module is used in multiple projects, I haven't figured out how to properly keep it tested for all and in sync. If I tag a particular version, then installing/upgrading apps in the wrong order will break previously installed material.
If I bundle all of my modules in CPAN-like bundles, it can check version requirements for me and fix that part of the issue, but that only covers modules, not templates.