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feat(builder): Add rootfs implementation for reading OCI images #413

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1 change: 1 addition & 0 deletions go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ require (
unikraft.com/x/guesstermwidth v0.0.0-20260813113709-544c471e0bc9
unikraft.com/x/iata v0.0.0-20260713183529-fd34645687a0
unikraft.com/x/image-spec v0.0.0-20260813113709-544c471e0bc9
unikraft.com/x/io v0.0.0-20260819084004-6de0d3f1ed2c
unikraft.com/x/joinerrgroup v0.0.0-20260304162956-523940cab1de
unikraft.com/x/kingkong v0.0.0-20260824095305-c69507b68d29
unikraft.com/x/kraftfile v0.0.0-20260522114044-e2da24d09716
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2 changes: 2 additions & 0 deletions go.sum
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Expand Up @@ -507,6 +507,8 @@ unikraft.com/x/iata v0.0.0-20260713183529-fd34645687a0 h1:wpRYHKQbrcJM4xSb8MyumZ
unikraft.com/x/iata v0.0.0-20260713183529-fd34645687a0/go.mod h1:M9v3TZKETfctR1aqFxM6UqYM+3DJ+nHKtqrxGb8X8oc=
unikraft.com/x/image-spec v0.0.0-20260813113709-544c471e0bc9 h1:S0Er9pKNkS4SdifkcXUAQ+P+ndMIBRMheyLZP8f6g9E=
unikraft.com/x/image-spec v0.0.0-20260813113709-544c471e0bc9/go.mod h1:7HwHLKMC6Ican+0HeMFVN8qI3mSyf0M64iEZj++FoPs=
unikraft.com/x/io v0.0.0-20260819084004-6de0d3f1ed2c h1:K/HL18OZWL/FeBC3/TcuOaQePMTzmYw4CzaKHxjf+Uk=
unikraft.com/x/io v0.0.0-20260819084004-6de0d3f1ed2c/go.mod h1:k4MCTNUTf7yB9LhOpH4Vj0RecXirtVE3gZLUw5jOFQo=
unikraft.com/x/joinerrgroup v0.0.0-20260304162956-523940cab1de h1:cm4FnPvnahRIK0derbI+T4ds1LsD5CFeyyAvIqcOCek=
unikraft.com/x/joinerrgroup v0.0.0-20260304162956-523940cab1de/go.mod h1:XND1VvLxwqKFGrmdwUTWps4WEpMm7HTHPQg9HWQtrxg=
unikraft.com/x/kingkong v0.0.0-20260824095305-c69507b68d29 h1:C87AsE6sNHtSwM6b+F/8lAOotIDSu3vJ8oUva/xRC9g=
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16 changes: 3 additions & 13 deletions internal/builder/build.go
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Original file line number Diff line number Diff line change
Expand Up @@ -231,19 +231,9 @@ func Build(ctx context.Context, opts BuildOpts) ([]*imagespec.Image, error) {
imgOpts = append(imgOpts, imagespec.WithInitrd(roots[i].Initrd))
roots[i].Initrd = nil
// The rootfs build may have produced a richer config (e.g. from
// a Dockerfile). Use it as the base and layer our overrides on top.
cfg = roots[i].Image.Config
if opts.Cmd != nil {
cfg.Cmd = opts.Cmd
}
if opts.Env != nil {
env := make([]string, 0, len(opts.Env))
for _, kv := range opts.Env {
env = append(env, fmt.Sprintf("%s=%s", kv.Key, kv.Value))
}
cfg.Env = append(env, cfg.Env...)
}
cfg.Labels = opts.Labels
// a Dockerfile or an OCI image). Use it as the base and layer our
// overrides on top.
cfg = applyConfigOverrides(roots[i].Image.Config, opts)
}
imgOpts = append(imgOpts, imagespec.WithImageConfig(cfg))

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27 changes: 7 additions & 20 deletions internal/builder/kraftfile.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,7 @@
package builder

import (
"cmp"
"fmt"
"path/filepath"

ocispec "github.com/opencontainers/image-spec/specs-go/v1"

Expand Down Expand Up @@ -58,22 +56,17 @@ func KraftfileToBuildOpts(dir string, kf *kraftfile.Kraftfile) (BuildOpts, error
if rom.Source == nil || rom.Source.Path == "" {
return BuildOpts{}, fmt.Errorf("rom entry is missing a source path")
}
romPath := filepath.Join(dir, rom.Source.Path)
romFormat := cmp.Or(rom.Format, kraftfile.FsTypeErofs)
romFormat := defaultRomFormat(rom.Format, rom.Source.Type)
romOpt := FSOpts{
Path: romPath,
Path: rom.Source.Path,
Format: romFormat,
Type: rom.Source.Type,
// Pad the file to page-size alignment. This is required by the platform
// which rejects ROM files that are not page-aligned.
Pad: 4096,
}
if romOpt.Type == "" {
typ, err := DetectSourceType(romPath)
if err != nil {
return BuildOpts{}, fmt.Errorf("detecting rom type for %q: %w", romPath, err)
}
romOpt.Type = typ
if err := resolveSource(dir, &romOpt); err != nil {
return BuildOpts{}, fmt.Errorf("resolving rom source %q: %w", rom.Source.Path, err)
}
opts.Roms = append(opts.Roms, romOpt)
}
Expand All @@ -82,18 +75,12 @@ func KraftfileToBuildOpts(dir string, kf *kraftfile.Kraftfile) (BuildOpts, error
if kf.Rootfs.Source == nil || kf.Rootfs.Source.Path == "" {
return BuildOpts{}, fmt.Errorf("rootfs entry is missing a source path")
}
opts.Rootfs.Path = filepath.Join(dir, kf.Rootfs.Source.Path)
opts.Rootfs.Path = kf.Rootfs.Source.Path
opts.Rootfs.Format = kf.Rootfs.Format
opts.Rootfs.Type = kf.Rootfs.Source.Type
opts.Rootfs.Dockerfile = kf.Rootfs.Source.Dockerfile
if opts.Rootfs.Dockerfile != "" && opts.Rootfs.Type == "" {
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craciunoiuc marked this conversation as resolved.
opts.Rootfs.Type = kraftfile.SourceTypeDockerfile
} else if opts.Rootfs.Type == "" {
typ, err := DetectSourceType(opts.Rootfs.Path)
if err != nil {
return BuildOpts{}, fmt.Errorf("detecting rootfs type for %q: %w", opts.Rootfs.Path, err)
}
opts.Rootfs.Type = typ
if err := resolveSource(dir, &opts.Rootfs); err != nil {
return BuildOpts{}, fmt.Errorf("resolving rootfs source %q: %w", kf.Rootfs.Source.Path, err)
}
}

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104 changes: 84 additions & 20 deletions internal/builder/kraftfile_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,9 @@
package builder

import (
"io/fs"
"os"
"path/filepath"
"testing"

"github.com/stretchr/testify/require"
Expand Down Expand Up @@ -48,7 +51,7 @@ func TestKraftfileToBuildOpts(t *testing.T) {
require.Equal(t, map[string]string{"label": "value"}, opts.Labels)
require.Equal(t, "unikraft.io/unikraft.org/base", opts.Runtime)
require.Equal(t, kraftfile.FsTypeErofs, opts.Rootfs.Format)
require.Equal(t, rootfsDir+"/Dockerfile", opts.Rootfs.Path)
require.Equal(t, filepath.Join(rootfsDir, "Dockerfile"), opts.Rootfs.Path)
require.Equal(t, kraftfile.SourceTypeDockerfile, opts.Rootfs.Type)
require.Len(t, opts.Platform, 1)
require.Equal(t, "x86_64", opts.Platform[0].Architecture)
Expand All @@ -60,43 +63,50 @@ func TestKraftfileToBuildOpts(t *testing.T) {
}, opts.Platform[0].OSFeatures)
}

func TestKraftfileToBuildOptsRootfsSourceError(t *testing.T) {
// TestKraftfileToBuildOptsResolvesSources asserts that every source leaves here
// resolved against the kraftfile directory and typed.
func TestKraftfileToBuildOptsResolvesSources(t *testing.T) {
rootfsDir := t.TempDir()
rootfsPath := "rootfs.tar"
romPath := filepath.Join(rootfsDir, "romdir")
require.NoError(t, os.Mkdir(romPath, 0o755))

runtime := kraftfile.Runtime("unikraft.io/unikraft.org/base")
kf := &kraftfile.Kraftfile{
Runtime: &runtime,
Rootfs: &kraftfile.FS{
Format: kraftfile.FsTypeCpio,
Format: kraftfile.FsTypeErofs,
Source: &kraftfile.FSSource{
Path: rootfsPath,
Path: "Dockerfile",
},
},
Roms: []kraftfile.FS{
{Source: &kraftfile.FSSource{Path: "romdir"}},
},
}

_, err := KraftfileToBuildOpts(rootfsDir, kf)
require.Error(t, err)
opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Equal(t, filepath.Join(rootfsDir, "Dockerfile"), opts.Rootfs.Path)
require.Equal(t, kraftfile.SourceTypeDockerfile, opts.Rootfs.Type)
require.Len(t, opts.Roms, 1)
require.Equal(t, romPath, opts.Roms[0].Path)
require.Equal(t, kraftfile.SourceTypeDirectory, opts.Roms[0].Type)
}

func TestKraftfileToBuildOptsRootfsPathJoined(t *testing.T) {
rootfsDir := t.TempDir()

// TestKraftfileToBuildOptsMissingSource asserts the fail-fast that resolving
// here buys: a bad path is reported before anything connects to BuildKit.
func TestKraftfileToBuildOptsMissingSource(t *testing.T) {
runtime := kraftfile.Runtime("unikraft.io/unikraft.org/base")
kf := &kraftfile.Kraftfile{
Runtime: &runtime,
Rootfs: &kraftfile.FS{
Format: kraftfile.FsTypeErofs,
Source: &kraftfile.FSSource{
Path: "Dockerfile",
},
Source: &kraftfile.FSSource{Path: "rootfs.tar"},
},
}

opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Equal(t, rootfsDir+"/Dockerfile", opts.Rootfs.Path,
"rootfs path must be joined with the kraftfile directory")
_, err := KraftfileToBuildOpts(t.TempDir(), kf)
require.ErrorIs(t, err, fs.ErrNotExist)
require.ErrorContains(t, err, "resolving rootfs source")
}

func TestKraftfileToBuildOptsDockerfileWithType(t *testing.T) {
Expand All @@ -117,7 +127,7 @@ func TestKraftfileToBuildOptsDockerfileWithType(t *testing.T) {

opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Equal(t, rootfsDir+"/context", opts.Rootfs.Path)
require.Equal(t, filepath.Join(rootfsDir, "context"), opts.Rootfs.Path)
require.Equal(t, "MyDockerfile", opts.Rootfs.Dockerfile)
require.Equal(t, kraftfile.SourceTypeDockerfile, opts.Rootfs.Type)
require.Equal(t, kraftfile.FsTypeErofs, opts.Rootfs.Format)
Expand All @@ -140,7 +150,7 @@ func TestKraftfileToBuildOptsDockerfileWithoutType(t *testing.T) {

opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Equal(t, rootfsDir+"/context", opts.Rootfs.Path)
require.Equal(t, filepath.Join(rootfsDir, "context"), opts.Rootfs.Path)
require.Equal(t, "MyDockerfile", opts.Rootfs.Dockerfile)
require.Equal(t, kraftfile.SourceTypeDockerfile, opts.Rootfs.Type,
"type must be inferred as dockerfile when dockerfile field is set")
Expand Down Expand Up @@ -172,3 +182,57 @@ func TestKraftfileToBuildOptsNoRootfs(t *testing.T) {
require.Equal(t, "x86_64", opts.Platform[0].Architecture)
require.Equal(t, "fc", opts.Platform[0].OS)
}

// TestKraftfileToBuildOptsRomOCIKeepsFormat verifies that a rom keeps the erofs
// default, except for an OCI source, which dictates its own format.
func TestKraftfileToBuildOptsRomOCIKeepsFormat(t *testing.T) {
rootfsDir := t.TempDir()
require.NoError(t, os.WriteFile(filepath.Join(rootfsDir, "rom.bin"), []byte("rom"), 0o644))

runtime := kraftfile.Runtime("unikraft.io/unikraft.org/base")
kf := &kraftfile.Kraftfile{
Runtime: &runtime,
Roms: []kraftfile.FS{
{Source: &kraftfile.FSSource{
Path: "index.docker.io/hello-world:latest",
Type: kraftfile.SourceTypeOCI,
}},
{Source: &kraftfile.FSSource{
Path: "rom.bin",
Type: kraftfile.SourceTypeTarball,
}},
},
}

opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Len(t, opts.Roms, 2)
require.Empty(t, opts.Roms[0].Format,
"an OCI rom must keep its own format rather than defaulting to erofs")
require.Equal(t, kraftfile.FsTypeErofs, opts.Roms[1].Format)
}

func TestKraftfileToBuildOptsRootfsOCIType(t *testing.T) {
rootfsDir := t.TempDir()

runtime := kraftfile.Runtime("unikraft.io/unikraft.org/base")
kf := &kraftfile.Kraftfile{
Runtime: &runtime,
Rootfs: &kraftfile.FS{
Format: kraftfile.FsTypeErofs,
Source: &kraftfile.FSSource{
Path: "index.docker.io/hello-world:latest",
Type: kraftfile.SourceTypeOCI,
},
},
Targets: []kraftfile.Target{
{Arch: "x86_64", Plat: "fc"},
},
}

opts, err := KraftfileToBuildOpts(rootfsDir, kf)
require.NoError(t, err)
require.Equal(t, "index.docker.io/hello-world:latest", opts.Rootfs.Path,
"OCI rootfs reference must not be joined with the kraftfile directory")
require.Equal(t, kraftfile.SourceTypeOCI, opts.Rootfs.Type)
}
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