Cumulus Linux (NVUE) — Deployment

Stage, diff, commit and roll back fabric changes for Cumulus Linux (NVUE) data center fabrics (VXLAN/EVPN). Part of the multi-vendor Data Center automation guide.

Repository

Cumulus

NVUE

REST API

VXLAN / EVPN

Render per-vendor config from the intent model

Stage as a candidate on Cumulus, then diff

Commit only the expected diff — roll back on failure

Setup, key commands & run examples

deploy.sh

Stage / diff / commit

The Cumulus Linux (NVUE) change workflow. Cumulus uses NVUE: nv set stages a revision, nv config diff previews it, nv config apply commits. There is a REST API mirroring the nv commands — prefer it over raw bash on modern releases.

deploy.sh

bash

# 1. stage:   nv set ... (staged revision)
# 2. diff:    nv config diff
# 3. commit:  nv config apply
# 4. revert:  nv config apply <revision> / nv config restore

deploy.py

Guarded commit

Render config from intent, stage it on Cumulus, preview the diff and only commit when it matches what you expect.

deploy.py

python

stage_config(rendered)                      # nv set ... (staged revision)
diff = preview_diff()                        # nv config diff
print(diff)
if "vlan 120" in diff:
    apply_config()                          # nv config apply
else:
    discard_config()                        # nv config apply <revision> / nv config restore

Best practices

Diff before every commit
Always review nv config diff (or gate it in CI) so no Cumulus change is applied blind.
Deploy leaf-pairs, not rows
Roll one MLAG/ESI pair at a time and verify before moving on, so redundancy survives a bad change.
Confirmed commits
Cumulus has no confirmed-commit — keep a rollback (nv config apply <revision> / nv config restore) one command away and watch the session.
Post-change verification
Re-read EVPN/VTEP state after each commit and abort the rollout if anything regressed.

Hands-on exercises

Guided practice tasks — copy the starter snippet, run it against a lab device, and extend it to meet the goal.

Exercise 1

Guarded VLAN rollout

Goal: Add an L2VNI to one Cumulus leaf pair: stage, print the diff, commit only if it contains the expected VLAN id.

exercise_1

python

rendered = render_l2vni(vlan=120, vni=10120)
# TODO: stage -> diff -> commit only if "120" in diff, else discard

Exercise 2

Rollback drill

Goal: Apply a bad change, detect the EVPN peer drop, and roll back with: nv config apply <revision> / nv config restore

exercise_2

bash

# apply change, then on failure:
nv config apply <revision> / nv config restore

Curated videos & guides

Checklist — pitfalls, gotchas & verification

Common pitfalls

•Committing without reviewing the diff first.
•Deploying both leaves of an MLAG/ESI pair at once and dropping the redundant path.
•Assuming Cumulus commit semantics match other vendors — they differ.

Gotchas to watch

•Cumulus stages a revision/candidate — make sure you commit the right one.
•Losing your management session mid-commit can lock you out without confirmed-commit.

Verify it works

•After deploy, re-read EVPN neighbors and confirm every peer returned to up.
•Diff running-config against intent post-change to prove zero unexpected drift.