How Do You Manage a Product Based on Linux?

Ryan writes "Following my advice, my company has decided to base it's new appliance on Linux. So far, it's worked out great. Linux gave us a huge jumpstart on development because of it's open nature and the information we've garnered from public mailing lists. We've added software, modified startup files, and have built our own kernel. Now the question is: How do you manage it all? Do you put it all in CVS or Subversion? Do you use the distro's packaging system (we're using Debian)? What does your build system look like?"

Comments

I don't understand the question

[Anonymous Coward]

You're building a whole new appliance, but your software engineers don't know how to manage a development process?

I mean... I'm not being nasty here, but you're in trouble, and I don't even know where anybody could start to give you advice. It would be one thing if you were looking for guidance on a regular small scale software project, but if you're jumping in feet first with a whole new large scale application and no idea how to guide the process...

Reproducability

[danpat]

If you're releasing a product to the public, the one word you need to keep in the back of your mind at all times is "reproducability".
Can you, at any point in the future, reproduce whatever version it is that customer X is having trouble with?

There are many ways to do this, ranging from taking complete snapshots of each "build" (requires lots of space, but fast to reproduce), to keeping a short list of the Debian packages installed (not much space, but slower to reproduce). It's a classic space-vs-time tradeoff.

I'd suggest you attempt to automate the system build as much as you can. Use virtualization tools like VMWare to help perform "builds" of your OS images. Most Linux distros have automated install processes. RedHat has "kickstart", Debian has "fai" (http://www.informatik.uni-koeln.de/fai/). At the minimum, you should version control the script you use to build your vmaware images, and the configuration script for fai/kickstart. This should let you re-build everything at some later stage.

When it comes to customising Debian systems, customised Debian packages are the way to go. If you're adding new files, package them up and deploy them as part of the automated install. If you're customising existing packages, edit their source and rebuild them with
customised version numbers, and list those versions of the packages in your fai script. You'll need to go through the whole version control process with each customised package too. (i.e. check it's source into a version control tool, tag it, apply your changes, tag it again, then build your .deb file). You can provide "answers" files for debconf so that no questions are asked during installation, and you can tweak various settings as you go along. If you've taken the VMWare approach, you can always login to the image and make final adjustments (just make sure they're scripted and version controlled) after the Debian install is complete.

Do a search for "customized debian", there are quite a few people doing similar things already.

Basically, make sure that the end product requires nothing more than a button push to produce. Anything less and you'll introduce the risk of someone forgetting to perform a step, or doing it wrong. That'll create a support nightmare down the track.

If you can reproduce easily what your customer has, you can also easily make a minimally invasive fix for them. That'll make them happy :-)

If you're looking for resources on this stuff in general, "configuration mangement" (http://en.wikipedia.org/wiki/Configuration_manage ment) is what you want to search for. Librarianship for software systems, kind of dry and boring, but oh-so-necessary.

Our situation

[Basje]

I work for an ASP. We've got a web application (built with Perl), running on Debian. At the moment we've about 15 servers (some dedicated to one large customer, some with over 50 customers) live, have 4 full time developers on the product, 15 people in total, and are quite succesful in our niche.

This is the short version of how we do things.

* We looked for an ISP where we rent the servers. They administer the servers (Debian stable), and install the perl modules, apache, etc. We don't have (want) root access to these machines: the ISP is responsible for the stability, and they do a good job. We ask them for changes/additional perl modules to be installed when needed. We've less than satisfactory experiences with several ISPs, make sure you find a good one.
* For a repository we use cvs. This is flexible enough for our needs, and there was some experience with the app. If you haven't got any experience with cvs, also take a look at subversion or mercurial, as you could benefit from the improvements there.
* As a cvs client we use eclipse. Great product, but unfortunately it is Java, and therefore slow. Some of the developers use the editor of eclipse, others use external editors (vi baby :)
* Our work environment is mixed. We all have a windows workstation, but for the actual development we have a server with a dedicated debian VPS for each developer. We connect to the VPS (which is hosted on our lan, and not accessible externally) through ssh, samba and x. The VPS are UML based, but nowadays when setting things up, we'd probably use Xen. The advantage of using VPSs is that it's easy to set up a clean developement/test environment.
* Have a release cycle, and try to stick with it. Most bugs are introduced when improperly tested code is implemented on live servers. Never edit directly on a live machine.

Our current shortcomings (i.e. pitfalls):
* Hardly any automated testing, and no formal testing procedures. Testing the application takes a lot of work, so it is often skimped. This is a risk, and introduced bugs are occasionnally missed.
* The release policy is not always honored due to deadlines. This puts a strain on the organisation, because, as noted above, it needs to be tested manually. This is when testing is skipped most of the times, and most bugs are introduced. It's a commercial tradeoff: let a customer wait, or take the risk. Depending on who and when you ask you get different answers.