feat: Pass Dockerfiles to unikraft build by danielvallance · Pull Request #503 · unikraft-cloud/cli

danielvallance · 2026-09-16T12:34:20Z

Now that the platform supports kernel-less images, it is not strictly necessary to pass a Kraftfile
to unikraft build - instead it can accept a
Dockerfile.

Passing a Dockerfile will build a image which
contains a rootfs based off the Dockerfile,
and no kernel.

The filename is used to determine which
type of file has been passed. If a directory
is passed, the Kraftfile takes precedence
over the Dockerfile.

When a Dockerfile is passed, the --arch argument
must be set so the CLI knows which architecure
to build for.

Kernel-less images can only be run on metros
with a default kernel installed.

Closes: TOOL-1439

Copilot

🟡 Changes recommended

Add end-to-end coverage for direct Kraftfile inputs, precedence, relative sources, and resource cleanup.

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Pull request overview

Adds Dockerfile-based, kernel-less image builds with architecture validation and Kraftfile precedence.

Changes:

Supports directory and direct-file build inputs.
Adds input-resolution tests, integration coverage, help snapshots, and documentation.

File summaries

File	Summary
`skills/unikraft-cli/SKILL.md`	Documents Dockerfile builds.
`README.md`	Adds Dockerfile build guidance.
`internal/cmd/build.go`	Loads inputs and validates architecture.
`internal/builder/rootfs.go`	Reuses Dockerfile detection.
`internal/builder/input.go`	Resolves Kraftfile and Dockerfile inputs; needs additional end-to-end coverage.
`internal/builder/input_test.go`	Tests input resolution.
`cmd/unikraft/testdata/TestHelp/images`	Updates image help output.
`cmd/unikraft/testdata/TestHelp/build`	Updates build help output.
`cmd/unikraft/integration/build_test.go`	Tests Dockerfile-only builds.

Review details

Files reviewed: 9/9 changed files
Comments generated: 1
Review effort level: Lite

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+		if isDockerfileName(filepath.Base(path)) {
+			return DockerfileToBuildOpts(path), nil
+		}
+		return loadKraftfile(ctx, path, filepath.Dir(path))


Copilot

🟡 Changes recommended

Dockerfile-only builds currently discard Dockerfile labels, and architecture documentation contradicts supported runtime-derived platforms.

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Review details

Files reviewed: 9/9 changed files
Comments generated: 3
Review effort level: Balanced

+func DockerfileToBuildOpts(path string) BuildOpts {
+	return BuildOpts{
+		Rootfs: FSOpts{
+			Path: path,
+			Type: kraftfile.SourceTypeDockerfile,
+		},
+	}


nderjung · 2026-09-17T06:45:32Z

+	ctx := integrationContext(t)
+	dockerfile := `
+FROM scratch
+LABEL org.unikraft.source=dockerfile org.unikraft.only=dockerfile


where is org.unikraft.source coming from?

IMHO we should use com. || cloud. for anything specifically cloud-based - so as not to mess with stuff in the OSS/KraftKit.

a similar label was in TestBuildCmdEnvLabelsIntegration - however that test and the tests I added do not rely on the meaning of the label at all, so am just going to change them to use com.example.* type labels

craciunoiuc · 2026-09-17T13:47:34Z

do let me know when I should check it out 😉

Copilot

🟢 Approval recommended

The implementation is consistent with the stated behavior and has comprehensive unit and end-to-end coverage.

Review details

Files reviewed: 12/12 changed files
Comments generated: 0 new
Review effort level: Balanced

danielvallance · 2026-09-18T11:10:34Z

@craciunoiuc stable integration test is failing because of a platform issue fixed in latest version

danielvallance · 2026-09-18T12:47:34Z

@craciunoiuc they pass now!

craciunoiuc

First set of comments

General note: Go people hate abstraction (for the sake of abstraction)

craciunoiuc · 2026-09-18T13:25:12Z

+// kraftfileNames are the Kraftfile names that a project directory can contain,
+// in order of precedence. The order is the name order of the directory listing.
+var kraftfileNames = []string{
+	"Kraftfile",
+	"Kraftfile.yaml",
+	"Kraftfile.yml",
+	"kraft.yaml",
+	"kraft.yml",
+}


If this isn't already in x/kraftfile then it should be probably 🤔

sure - I can add that afterwards

It's already there 🤔

craciunoiuc · 2026-09-18T13:27:27Z

+func loadKraftfile(ctx context.Context, path, dir string) (BuildOpts, error) {
+	kf, err := kraftfile.ParseFile(path, kraftfile.WithSkippedVersionCheck())
+	if err != nil {
+		return BuildOpts{}, err
+	}
+	if semver.Compare(kf.Spec, kraftfile.SpecVersionMin) < 0 {
+		log.G(ctx).Warn().
+			Str("spec", kf.Spec).
+			Str("min", kraftfile.SpecVersionMin).
+			Msg("Kraftfile spec version is older than minimum; parsing is best-effort")
+	} else if semver.Compare(kf.Spec, kraftfile.SpecVersionMax) > 0 {
+		log.G(ctx).Warn().
+			Str("spec", kf.Spec).
+			Str("max", kraftfile.SpecVersionMax).
+			Msg("Kraftfile spec version is newer than maximum; parsing is best-effort")
+	}
+	return KraftfileToBuildOpts(dir, kf)
+}


just one use place, so inline

do you mind if i keep this as its own function? it is used twice so i think having it as its own function keeps it simpler

well if you ask me so nicely how can I say no

Now that the platform supports kernel-less images, it is not strictly necessary to pass a Kraftfile to unikraft build - instead it can accept a Dockerfile. Passing a Dockerfile will build a image which contains a rootfs based off the Dockerfile, and no kernel. The filename is used to determine which type of file has been passed. If a directory is passed, the Kraftfile takes precedence over the Dockerfile. When a Dockerfile is passed, the --arch argument must be set so the CLI knows which architecure to build for. Kernel-less images can only be run on metros with a default kernel installed. Closes: TOOL-1439 Signed-off-by: Daniel Vallance <daniel@unikraft.com>

unikraft.org is the OSS project and we don't want to confuse that with our cloud offering Signed-off-by: Daniel Vallance <daniel@unikraft.com>

craciunoiuc

I think you have like a crazy commit message rule.

You can ask it for under 50 lines for titles and under 70 lines for commit bodies.

Other than that it looks good to me I think? @jedevc you're free to do a pass

jedevc · 2026-09-21T15:26:41Z

All of this logic is very similar to ParseDirectory.

Instead of doing all that, can we just try that first, then if we detect an error (probably need to make an exported "no kraftfile found in directory" error type), try and load from a dockerfile?

Then we don't need to import all this logic again.

danielvallance requested a lite review from Copilot September 16, 2026 12:34

Copilot started reviewing on behalf of danielvallance September 16, 2026 12:34 View session

Copilot AI reviewed Sep 16, 2026

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Comment thread internal/builder/input.go

if isDockerfileName(filepath.Base(path)) {

return DockerfileToBuildOpts(path), nil

}

return loadKraftfile(ctx, path, filepath.Dir(path))

danielvallance force-pushed the danielvallance/dockerfile_builds branch from 4acb2ae to c1c1158 Compare September 16, 2026 14:36

danielvallance requested a balanced review from Copilot September 16, 2026 14:42

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danielvallance force-pushed the danielvallance/dockerfile_builds branch 2 times, most recently from c1c1158 to f6f6e9b Compare September 16, 2026 15:02

nderjung reviewed Sep 17, 2026

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danielvallance force-pushed the danielvallance/dockerfile_builds branch from f6f6e9b to 55d7e45 Compare September 18, 2026 10:11

danielvallance marked this pull request as ready for review September 18, 2026 10:11

danielvallance requested review from craciunoiuc and a balanced review from Copilot September 18, 2026 10:11

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craciunoiuc requested changes Sep 18, 2026

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craciunoiuc requested a review from jedevc September 18, 2026 13:30

danielvallance force-pushed the danielvallance/dockerfile_builds branch from 55d7e45 to 0abe268 Compare September 20, 2026 20:45

danielvallance added 2 commits September 21, 2026 10:01

chore: Remove org.unikraft.* labels from tests

7f27c21

unikraft.org is the OSS project and we don't want to confuse that with our cloud offering Signed-off-by: Daniel Vallance <daniel@unikraft.com>

danielvallance force-pushed the danielvallance/dockerfile_builds branch from 0abe268 to 7f27c21 Compare September 21, 2026 09:01

danielvallance requested a review from craciunoiuc September 21, 2026 09:02

craciunoiuc reviewed Sep 21, 2026

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jedevc reviewed Sep 21, 2026

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danielvallance commented Sep 16, 2026

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🟡 Changes recommended

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🟢 Approval recommended

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nderjung Sep 17, 2026 •

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