Very interesting discussion. With all due respect to Mr. Humble, and I am a big fan of CD, I am going to venture to say that you don't understand Maven very well. As a thought experiment, you are correct in saying that a build based on snapshots is not reproducible. As a more practical matter however, I feel it is.
Dependencies come in two flavors, our and theirs (internal and 3rd party). If, all of *our* dependencies are SNAPSHOT (we're doing the developing) and all of *theirs* are 'versioned' then the build is in fact reproducible assuming you build everything from a particular repo version even with the default auto-update setting (in fact, it's required). ________________________________ Curt Yanko | Continuous Integration Services | UnitedHealth Group IT Making IT Happen, one build at a time, 600 times a day -----Original Message----- From: jhumble [mailto:[email protected]] Sent: Sunday, November 07, 2010 11:15 AM To: [email protected] Subject: RE: Continuous Delivery and Maven Hey Todd The whole point of continuous delivery is that every check-in creates a potential release candidate. When you're doing continuous deployment, you could be releasing multiple times a day, so you don't bother cutting branches or tagging or any of that stuff because of the overhead. I'd rather not get into the justification for this process on this thread - but I wrote a book on it if you're interested: http://www.amazon.com/gp/product/0321601912 and many other people have blogged about it. You're right that creating a concrete release for each commit could potentially use up a lot of space - but that's fine, you can just delete the older ones. What this *does* mean in turn though is that it is essential to be able to recreate any given build given the version in source control it came from, and this is where Maven falls down. Snapshots just aren't suitable because they aren't reproducible: what the snapshot looks like depends not only on what versions of the dependencies are available at the time the snapshot is created, but also what Maven's configuration and plug-ins happen to be at the time you run it (assuming Maven is configured to auto-update - the default). I can't revert back to a particular revision in version control, run maven, and be sure that the artifact it generates is identical to the one it created when the commit was initially triggered. Ideally what I'd like is for Maven to explicitly support the continuous delivery model and provide snapshots that are reproducible. Failing that, a guide to configuring Maven so that its binaries are reproducible (for example by switching off auto-update, and having sufficient metadata stored in pom files and Maven's artifacts repository to know what the state of each of the dependencies was at any given time. -- View this message in context: http://maven.40175.n5.nabble.com/Continuous-Delivery-and-Maven-tp3245370 p3254090.html Sent from the Maven - Users mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected] This e-mail, including attachments, may include confidential and/or proprietary information, and may be used only by the person or entity to which it is addressed. If the reader of this e-mail is not the intended recipient or his or her authorized agent, the reader is hereby notified that any dissemination, distribution or copying of this e-mail is prohibited. If you have received this e-mail in error, please notify the sender by replying to this message and delete this e-mail immediately. --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
