The deployment process

A deployment is made up of several conceptual steps, deliberately not one-to-one with the CLI commands: one command may run several steps, and some are never exposed as a command of their own. For the commands themselves see the CLI reference.

Step	Description	Run by
Compare	Compare the current deployment snapshot against the modulefiles and built modules that actually exist, confirming the deployment area is healthy.	compare
Validate	Diff the new configuration against the current snapshot to determine the set of actions to take, and check those actions are permitted by the release lifecycle.	validate, sync
Build	Generate entrypoint scripts, configuration files and environment variables for each changed Module, writing them to the build area.	sync (validate --test-build)
Deploy	Move the built Modules from the build area into the Modules Area, link each modulefile into the live or deprecated tree according to its status, and update default versions.	sync

Why build and deploy are not separate commands

There is no standalone build or deploy command. sync always runs them together, so a half-built Module is never exposed to users: either a version is built and linked into place, or nothing changes.

How the steps fit together

sync is the only step that writes to the deployment area; compare and validate are read-only checks run before it. See snapshots and the compare safety net for how the snapshot ties them together, and drive deploy-tools from CI for the order a pipeline runs them in.