Right after I read eXtreme Programming: Explained [affiliate link], we built a CI system at Droplets (where I worked). CruiseControl didn’t exist yet, so anyone trying to do this just figured it out for themselves. Our system was based on a physical build token.

All of our desktop machines were named after movies—the CI Build Machine was named Goodfellas. I printed out an 5×7 poster of the movie and put the manual instructions for doing CI on the back. Then, I laminated it. You needed to have this card on your desk if you wanted to commit code.

Here is what it said on the back of the card:

1. You must have this card on your desk to proceed
2. Commit your code
3. Go over to Goodfellas (don’t take the card)
4. Get your changes
5. Run the build and test scripts
6. If it’s broken, fix it
7. If you know someone was waiting for this card, give it to them
8. Otherwise, put the card back where you found it

The build and test were automated, but you did need to manually grab the card.

Doing this solved our problem of broken builds caused by “it worked on my machine” problems. Seems antiquated now, but before easy branching and merging, this one-at-a-time verification caught a lot of problems early.