How to automate publish in a CI environment?

Question

We are using lerna to manage a monorepo and we want to automate the publishing process:

1. The developer makes changes in one of the packages in the monorepo
2. The CI detects that changes have been made
3. The CI builds the package, the patch level is automatically incremented, and the new package is published, tags are pushed to git, etc.

To avoid infinite cycles ( build -> tag -> push -> build -> tag -> ...), the CI should only build if there are indeed changes - hence step 2

1. How can one do that with lerna? Is 'from-git' an option?

2. Is there any other "best practice" how to use lerna in a CI environment?

Mannequin