what

• Emit a warning to STDERR that an out-of-date version of atmos is in use
• Support a atmos.yaml configuration setting to specify a list acceptable semver ranges
• Use the https://api.github.com/repos/cloudposse/atmos/releases API to determine the latest release satisfying semver ranges

why

Atmos is under active development. Bugs are constantly fixed. Older versions cause grief that could be avoided by upgrading.

example

versions:
- '~> 1.4'
- '! 1.4.2'

atmos version
1.4.1

atmos terraform plan...
WARNING: Latest version of atmos is 1.4.2; you're using atmos 1.4.1
...