Unikraft

Unikraft CLI Reference

Build and deploy unikernels with the unikraft CLI.

• Documentation: https://unikraft.com/docs/cli
• CLI source & releases: https://github.com/unikraft-cloud/cli
• Platform: https://unikraft.cloud

Targets the new unikraft CLI 0.4.x (verified against 0.4.1) and the Unikraft Cloud REST API v1. Run unikraft version to check; if the major or minor differs, re-verify flags/commands against --help before following this skill.

New CLI vs legacy kraftkit — they are different tools

The binary is unikraft (from unikraft-cloud/cli). It replaces the legacy kraftkit kraft (v0.12.x). They are separate programs with:

• a different command tree (unikraft run / unikraft build / unikraft instances …, not kraft cloud deploy),
• a separate auth store — a kraft login / UKC_TOKEN env from kraftkit does not authenticate unikraft; you must run unikraft login (see below). The new CLI writes its own profile under ~/.config/unikraft, kraftkit uses ~/.config/kraftkit,
• packaging split from deploy — unikraft build --output <ref> publishes an image, then unikraft run --image <ref> deploys it (kraftkit did both in one kraft cloud deploy).

If you see kraft, UKC_TOKEN, kraft cloud, or --rollout in a config or runbook, it is the legacy CLI — translate it to the new commands here.

Important: running commands

When working with unikraft commands:

1. Show the command first — display it in a copy-paste code block before running it.
2. Authenticated (cloud) commands need a login — anything hitting Unikraft Cloud (run, instances, services, images, metros, api, a publishing build) fails with profile not setup until unikraft login has run in that environment. The AI's shell may not be logged in; if a command returns profile not setup, hand it to the developer to run.
3. Let the developer run it when a login or a real deploy is involved.

Installation

• CI (GitHub Actions): unikraft/setup-action@v1 — installs the CLI and logs in headlessly. Inputs: version (latest/stable, dev/staging, or a release tag), token (login token), organization. It downloads the release asset unikraft-cli_<version>_<os>_<arch>.tar.gz from unikraft-cloud/cli.

  - uses: unikraft/setup-action@v1
    with:
      version: 0.4.1
      token: ${{ secrets.KRAFTCLOUD_TOKEN }}
      organization: my-org
  

• Local: unikraft upgrade self-updates an installed CLI. Otherwise pull the tarball for your platform from https://github.com/unikraft-cloud/cli/releases (it holds the unikraft binary at its root).

• Nix: the CLI is not in nixpkgs (only the legacy kraft is), but the Unikraft team maintains a NUR flake at github:unikraft/nur exposing packages.<system>.{unikraft-cli, unikraft-cli-staging, kraftkit} (+ an overlay). Add it as a flake input and take unikraft-cli — or unikraft-cli-staging while the stable attr is being fixed upstream.

Authentication

The new CLI reads the token from a file or stdin, not an env var, and associates the session with an organization.

# From a file:
unikraft login --token /path/to/token --organization my-org

# From stdin (no token on disk / no token in argv):
printf '%s' "$UKC_TOKEN" | unikraft login --token - --organization my-org

--organization is resolved from the control plane if omitted. A successful login stores a profile (named after the organization) under ~/.config/unikraft. Manage profiles with:

unikraft profile list          # profiles + their metros + which is active
unikraft profile use <name>    # switch active profile

Global flags / env available on every command: --profile ($UNIKRAFT_PROFILE), --config ($UNIKRAFT_CONFIG), --timeout ($UNIKRAFT_TIMEOUT), --log-level ($UNIKRAFT_LOG_LEVEL), --log-type, --[no-]telemetry.

Metros

Most write operations take --metro <m>. List them with unikraft metros list:

Use (current)	Endpoint
fra, dal, sin, was, sfo	https://api.<metro>.unikraft.cloud

unikraft metros list also shows legacy metros fra0, dal0, sin0, was1 on api.<metro>.kraft.cloud — these are the old kraft.cloud endpoints. Use the suffix-less names only; treat any <metro>0 as legacy.

[!IMPORTANT] Only the create verbs take --metro — unikraft run and unikraft services create. The read/manage verbs (instances list/get/delete/logs, images list, services get) reject --metro with unknown flag --metro; they take a bare name (the logged-in profile spans metros) or a --filter 'metro==<m>'. This bites in CI: piping a failed instances delete <name> --metro fra through || true silently skips the delete, and the next run then fails with "instance already exists".

Command tree

Commands
  unikraft run                 # Run an image as an instance (deploy)
  unikraft build               # Build a Unikraft project into a container image
  unikraft tui                 # Browse resources in a TUI

Resources
  unikraft metros              # List/inspect cloud metros
  unikraft quotas              # Show quota usage
  unikraft instances           # Manage instances  (aliases: instance, vm, vms)
  unikraft services            # Manage service groups (svc, svcs)
  unikraft volumes             # Manage persistent volumes (vol, vols)
  unikraft certificates        # Manage TLS certificates (cert, certs)
  unikraft images              # Manage images (image, img, imgs)

Utilities
  unikraft api <endpoint>      # Authenticated raw REST call (e.g. /v1/instances)
  unikraft version             # Version info
  unikraft upgrade             # Self-update the CLI
  unikraft completion          # Shell completions

Config
  unikraft login / logout      # Authentication
  unikraft profile             # get / list / use
  unikraft config              # Manage CLI configuration

Build (package an image)

# Build the project in the current directory and PUBLISH to the registry.
# The <org> prefix is your organization (see `unikraft profile list`).
unikraft build . --output <org>/my-app:latest

# Build and save to a LOCAL OCI archive (no publish):
unikraft build . --output ./dist/my-app.oci.tar

# Build-time inputs and secrets:
unikraft build . --build-arg VERSION=1.2.3 --secret id=npm,src=$HOME/.npmrc

Flags: -o/--output, --build-arg, --no-cache, --secret, --ssh, --insecure, plus the global --timeout=<duration>. The input path defaults to ..

Run (deploy an instance)

# Deploy a new instance exposing an HTTPS service:
unikraft run --metro fra --image <org>/my-app:latest \
  -p 443:8080/http+tls -p 80:443/http+redirect \
  -m 2048M --restart on-failure -e NODE_ENV=production

# Preview without deploying:
unikraft run --metro fra --image <org>/my-app:latest --dry-run

Common flags: --metro, --image, -n/--name, -e/--env, -m/--memory (binary units, e.g. 2048M), --vcpus, -p/--publish (<src>:<dest>[/<handlers>]), --domain, --service (attach to an existing service group), --restart (on-failure …), --scale-to-zero, -v/--volume, --replicas, --rm, --follow, --dry-run.

Memory units changed from legacy kraftkit: -M 2048 (MiB) → -m 2048M.

Instances, services, images

unikraft instances list                    # or: ls
unikraft instances get <name>              # inspect
unikraft instances logs <name>             # console output
unikraft instances wait <filter>           # block until instances match (readiness gate)
unikraft instances delete <name>           # remove
unikraft instances start|stop|suspend|restart <name>

unikraft services list                     # service groups (load balancers)
unikraft services get <name>
unikraft services create …                 # create a named service group
unikraft services edit <name>              # change its config / instance set

unikraft images list                       # image refs + digests (--filter 'ref~="my-app"')
unikraft images build                      # same engine as `unikraft build`
unikraft images delete <ref>

volumes (create/attach/detach/clone/import/…) and certificates (create/get/wait/…) follow the same verb pattern.

[!WARNING] Reading an instance dumps its secrets. instances list -o json/-o yaml and instances get (without -f) return the instance's full runtime.env — including secret values such as DATABASE_URL — in cleartext. When you only need identifiers, field-limit the output: unikraft instances list -f name -o quiet (names only, no env). Never pipe an un-limited instance read into shared logs, CI output, or an issue.

Rolling updates (zero-downtime)

The new CLI has no single --rollout flag (kraftkit's kraft cloud deploy --rollout remove_sequential). A zero-downtime swap of an instance behind an existing service group is composed from primitives:

1. unikraft run --service=<group> --image <new-ref> … — start a new instance and attach it to the service group that owns the domain/ports (do not re-pass -p/--domain; the group owns those). Omit --name so the new instance gets a unique name and can run alongside the old one.
2. unikraft instances wait <filter> — wait until the new instance is ready.
3. unikraft instances delete <old-name> — remove the previous instance.

Confirm the exact recommended sequence (and whether a built-in rollout exists in your CLI version) with unikraft run --help / the Unikraft team before relying on it for a production deploy.

[!IMPORTANT] Check quota headroom before a rolling update. The overlap briefly runs two instances, so it needs ~2× the instance's memory + vCPUs at once. Run unikraft quotas [--metro <m>] first (optional --metro, no subcommand): if adding a second instance would exceed the memory or instance cap, fall back to delete-then-recreate (accepting a brief gap) or request a quota bump. Near the cap, a rolling run fails with a quota error mid-deploy.

Kraftfile (spec v0.7)

Keep the Kraftfile (and the Dockerfile it references) at the build context root — the rootfs path can't reach parent directories, and the Docker build needs the repo root as context to COPY sibling folders.

spec: v0.7
name: my-server
# base-compat runs the node binary bundled in the image.
runtime: base-compat:latest

labels:
  cloud.unikraft.v1.instances/scale_to_zero.policy: "off"

rootfs:
  source: ./Dockerfile
  format: erofs
cmd: ["/usr/local/bin/node", "/app/dist/main.mjs"]

Deployment example (build once, deploy the image)

# 1) Log in (once per environment).
printf '%s' "$UKC_TOKEN" | unikraft login --token - --organization my-org

# 2) Build + publish a versioned image.
unikraft build . --output my-org/my-app:2026.7.9 --timeout 10m

# 3) First deploy — create the service group, then run into it.
unikraft services create --name my-app \
  --domain my-app.example.com 443:8080/http+tls 80:443/http+redirect
unikraft run --metro fra --service my-app --image my-org/my-app:2026.7.9 \
  -m 2048M --restart on-failure -e NODE_ENV=production

# 4) Subsequent deploys — see "Rolling updates" above.

# Verify:
unikraft instances list
curl -sf https://my-app.example.com/health
unikraft instances logs my-app-<suffix>

Troubleshooting

Symptom	Cause / fix
profile not setup	Not logged in — run unikraft login (kraftkit's login/UKC_TOKEN doesn't count).
unknown flag --metro on */list	List/get subcommands scope by profile/--filter, not --metro.
Image builds but instance won't boot	Check runtime, the cmd path, and that env vars the app needs are passed with -e.
504 Gateway Timeout	Scale-to-zero cold start — set the scale-to-zero policy off for latency-sensitive services.
rootfs / COPY build failures	Keep the Kraftfile + Dockerfile at the build-context root; no ../ in the rootfs path.
Legacy fra0/kraft.cloud host in a ref	Replace with the suffix-less metro (fra, api.fra.unikraft.cloud).

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Unikraft Cloud REST API (v1)

The CLI wraps a REST API. Reach for it via unikraft api <endpoint> (uses the logged-in profile), or call it directly with a bearer token for automation.

unikraft api /v1/instances                       # via the CLI (logged-in profile)

curl https://api.fra.unikraft.cloud/v1/instances \
  -H "Authorization: Bearer $UKC_TOKEN"          # raw, any HTTP client

• Base URLs are metro-scoped: https://api.<metro>.unikraft.cloud/v1 for fra, dal, sin, was, sfo. Never use a <metro>0 legacy host.
• Every response uses the {status, message, data, errors, op_time_us} envelope; bulk endpoints return per-item status.

Full endpoint tables, curl examples, and gotchas: references/api-v1.md.

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Examples repository

Reference examples (Kraftfiles + Dockerfiles for many runtimes): https://github.com/unikraft-cloud/examples.