feat: Add 'volume import' command by craciunoiuc · Pull Request #245 · unikraft/cli

craciunoiuc · 2026-04-03T11:27:54Z

This adds initial support for volume importing. As before, only CPIO files are supported for importing due to how the "backend" of this is built.

To add to this, only files and directories are supported right now. I could not figure out how to correctly split the dockerfile implementation to make it stop before creating the OCI archive using imagespec, as I needed it to give me a .cpio file.
Dockerfiles also work now.

~~To make this fully work, proto needs to be updated and the delete_on_stop flag needs to be renamed to delete-on-stop.~~
~~Switched to new way of providing features that works.~~
Sdk fixed.

~~Finally, I don't really like how things sit but I couldn't find a better way to break things apart whilst also keeping the general repo structure (aka not refactoring everything 😈)~~
I did the refactoring hehe.

~~tldr: if you give it no --source it will use the workdir and assume it's a Kraftfile in there (or fail if not)~~
Removed.

If you give it a --source it uses that, be it a CPIO (directly uses it), or Directory (Packages it), or Dockerfile (Builds it).

TODO: Regenerate tests before merging

Blocked on: https://github.com/unikraft-cloud/platform/pull/705
Closes: TOOL-694

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Pull request overview

Adds an initial unikraft volume import command to import local data into an existing Unikraft Cloud volume by packaging the source into a CPIO archive and streaming it to a temporary “volimport” instance over TLS.

Changes:

Introduces volume import CLI command that builds/uses a CPIO archive and streams it to a per-volume import instance.
Adds internal/builder.BuildImportRootfs helper to normalize an import source (directory vs existing CPIO).
Implements a TLS streaming protocol in internal/builder/cpio for sending CPIO entries and handling ack/stop responses.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
internal/cmd/volumes.go	Adds `volume import` command, instance spawning, TLS connect, and auth token generation.
internal/builder/import.go	Adds helper to build/validate an importable CPIO archive from a directory or existing CPIO file.
internal/builder/cpio/cpio.go	Adds CPIO magic detection and the TLS streaming/ack protocol implementation.
cmd/unikraft/volumes_test.go	Extends CLI help smoke test to include `volume import --help`.

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craciunoiuc · 2026-04-15T14:58:16Z

I split all the suggested changes into separate commits. I will need to squash some of them up before it's ready to review again.

Currently a bit broken as the imgspec does not return the path to the computer layer.

Also rootfs building does not work without dockerfiles. (aka with directories or files)

With these out of the way it should work again.

jedevc · 2026-04-15T15:06:33Z

Currently a bit broken as the imgspec does not return the path to the computer layer.

Why do you need the "computer layer"? Do you need to open the file? If so, you can call Open. What specifically needs the path here?

Also rootfs building does not work without dockerfiles. (aka with directories or files)

Indeed 🎉 I was hoping this was one of the things you might take a look at at some point, or even as part of this (though maybe in a separate PR).

craciunoiuc · 2026-04-15T15:25:32Z

I was hoping this was one of the things you might take a look at at some point

Hmm, then something is weird, because you told me to revert the file/directory/dockerfile detection that I previously had. (which is why I did them as commits on top instead of overwriting hehe.

Why do you need the "computer layer"?

Lol, not sure how I wrote that. I wanted to say the rootfs layer. I was hoping the imagespec directory would give me to path to the file if I call images[0].Initrd.Path() on it for examples. But it seems that it's always empty.

jedevc · 2026-04-15T15:42:29Z

The detection should exist, yes, but it should be extracted - it shouldn't be done just for the volume imports. We should have one reusable function that does "pass this thing in, and build a rootfs from it". We may need to rework those functions and everything so that the signatures all work out. What we need to avoid is rewriting the same detection everywhere.

jedevc · 2026-04-15T15:44:37Z

Path() is not documented well, but it's the path inside the tarball. e.g. for a packaged kernel, the kernel lives inside the tarball at /unikraft/bin/kernel for example. Path() says which of those it's at.

Looking at how it's used actually... we could remove that method entirely.

craciunoiuc · 2026-04-17T10:01:47Z

All comments make sense, will address, next time you see this PR it will have the changed commit history

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Pull request overview

Copilot reviewed 18 out of 19 changed files in this pull request and generated 7 comments.

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craciunoiuc · 2026-04-17T14:28:42Z

^ Will do monday.

craciunoiuc · 2026-04-20T08:23:42Z

Integration is really weird, at least 2-3 things related to the server itself

PR should be ready

jedevc

Only nits, happy to merge when they're resolved.

jedevc · 2026-04-20T13:24:56Z

+	RootfsTypeErofs      RootfsType = "erofs"
+	RootfsTypeDir        RootfsType = "dir"
+	// Unused for now, but may be useful in ROMs
+	RootfsTypeFile RootfsType = "file"


We should remove this for now if it's not being used.

jedevc · 2026-04-20T13:25:30Z

-		} else {
-			return BuildOpts{}, fmt.Errorf("unable to determine rootfs type for source %q", kf.Rootfs.Source)
+		sourcePath := filepath.Join(dir, kf.Rootfs.Source)
+		typ, err := DetectRootfsType(sourcePath)


Can you follow-up with a PR to x/kraftfile to add a field for this explicitly?

shouldn't I do this before, so I can rebase this?

I would keep the detection logic here for when that field is empty. Up to you on ordering, I have no preference.

Signed-off-by: Cezar Craciunoiu <cezar@unikraft.io>

Implements 'volimport' instance lifecycle helpers. Also adds the communication protocol with the instance. Finally add a rootfs build helper for formatting properly. Signed-off-by: Cezar Craciunoiu <cezar@unikraft.io>

Signed-off-by: Cezar Craciunoiu <cezar@unikraft.io>

craciunoiuc · 2026-04-21T07:30:51Z

finally, it feels like 1 morbillion years have passed

Signed-off-by: Justin Chadwell <justin@unikraft.com>

jedevc

Reviewed-by: Justin Chadwell justin@unikraft.com
Approved-by: Justin Chadwell justin@unikraft.com

craciunoiuc requested review from Copilot and jedevc April 3, 2026 11:27

Copilot started reviewing on behalf of craciunoiuc April 3, 2026 11:28 View session

Copilot AI reviewed Apr 3, 2026

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craciunoiuc force-pushed the craciunoiuc/add-volume-import branch 4 times, most recently from 75717cb to dd16f28 Compare April 7, 2026 09:32

craciunoiuc marked this pull request as ready for review April 7, 2026 09:50