Advanced Terraform Module Usage: Versioning, Gotchas, and Reuse Across Environments

Day 9 of the 30-Day Terraform Challenge — and today I learned the hard-won lessons that separate "I know how to write a module" from "I can safely share modules with a team." Yesterday I built my first module. Today I learned why modules break in production, how to version them like real software, and why pinning versions is the difference between "it works" and "it works every time, for everyone." The Problem: Modules Aren't Magic Yesterday's module worked perfectly when I called it from a local path. But the moment I tried to share it? Things got messy. Three gotchas caught me off guard: Gotcha 1: File Paths Lie to You I had a user data script in my module: user_data = file ( "user-data.sh" ) Worked fine when testing locally. Then I called the module from a different directory: Error: Error reading file "user-data.sh": no such file or directory The problem: file() resolves paths relative to where Terraform is run, not relative to the module! The fix: Always use ${path.module} : user_