Check for drift

Drift is NetBox changing under a deployment: someone edits a field the design sets, or deletes an object it created. Planning the deployment again shows it. The tutorial's Check for drift makes some and finds it.

1. Go to Deployments and open the deployment.
2. Select Check drift. It plans the deployment again in the background, with the design and variables it was applied with, and stays on the page.

In sync means NetBox still matches the design. Drifted says how many changes the plan found: Review opens it, showing each field NetBox changed and the value the design sets, and each object the deployment created that NetBox no longer has.

A change to a fact that identifies an object, such as a device renamed in NetBox, is shown as a move, like a rename in the design is: the deployment knows the device by its NetBox id, finds it under its new name, and the plan is one update that puts the name back, with the interfaces and cables under it untouched. Where the changed fact can't be written back, as a cable's ends can't, the plan deletes the deployment's own object by its id and creates it again, and says so on the pair.

What to do with it is yours to decide:

• Put NetBox back: apply the plan. The field returns to what the design sets; the missing objects are created again.
• Keep what NetBox has: change the design so it no longer sets that field, or sets it to the value NetBox now holds, then Redeploy the deployment with the new version. Only what the design declares counts, so a field the design stops setting is never drift again.
• Leave it: a check changes nothing, and there is nothing to discard. The next check reports the drift again until one of the two above is done.

A check compares and reports; it does not reopen the deployment's plan. The deployment keeps its applied state, Check drift stays available, and a later Redeploy that is applied replaces the check's plan.

A deployment of several designs has Check drift of all above its designs. It checks each from the plan that applied it, reading NetBox once, and sums them up: in sync when every design is, or how many objects differ and in how many designs, with an object two designs share counted once. Each design's own result and Review stay in its section, because a plan is per design and there is no one plan to apply.

Only what the design declares counts. A field the design doesn't set can be changed in NetBox freely: it is never reported as drift, and applying never touches it.

Check drift compares NetBox with the version of the design the deployment applied, so a design edited since is not reported as drift; the Deployments page says the design has changed instead, and Redeploy is how you move to it.

The history

Each check is an entry in the deployment's history, under its actions: Checked for drift, with what it found (in sync, or the counts), when and by whom. Open shows the plan; a check whose plan is still pending can be applied from there. A check that a later apply replaced says superseded by a later plan; one that was applied says Drift put back.

A deploy or redeploy that is planned and not applied has Replan, which plans again with the same variables, and Discard plan, which closes it without applying; nothing in NetBox changes. A drift check has neither: there is nothing to discard. To plan the deployment again, or change its variables, use Redeploy on the deployment.