pkg: add new imagefilter package with an ImageFilter

This commit creates a new `imagefilter` package that can be used
to create a filter for the available images that can be build by
the images library.

Support for prefixes and fnmatch style globbing is available.

This will eventually allows us to do:
```
$ image-builder --list-images --filter arch:aarch64 --filter type:qcow*
or
$ image-builder --list-images --filter ami
```

The filtering can be both with or without a prefix, i.e. when doing
a "simple" search all common fields (disro,arch,imageType) are checked
but with a prefix search things can be narrowed down more.

Initially the following prefixes filters are supported:
"distro:" - the distro name, e.g. rhel-9, or fedora*
"arch:" - the architecture, e.g. x86_64
"type": - the image type, e.g. ami, or qcow?
"bootmode": - the bootmode, e.g. "legacy", "uefi", "hybrid"

(Split out from the spike in osbuild#997)

pkg/imagefilter/filter.go

@@ -0,0 +1,92 @@
+package imagefilter
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+
+	"github.com/gobwas/glob"
+
+	"github.com/osbuild/images/pkg/distro"
+)
+
+func splitPrefixSearchTerm(s string) (string, string) {
+	l := strings.SplitN(s, ":", 2)
+	if len(l) == 1 {
+		return "", l[0]
+	}
+	return l[0], l[1]
+}
+
+// newFilter creates an image filter based on the given filter terms. Glob like
+// patterns (?, *) are supported, see fnmatch(3).
+//
+// Without a prefix in the filter term a simple name filtering is performed.
+// With a prefix the specified property is filtered, e.g. "arch:i386". Adding
+// filtering will narrow down the filtering (terms are combined via AND).
+//
+// The following prefixes are supported:
+// "distro:" - the distro name, e.g. rhel-9, or fedora*
+// "arch:" - the architecture, e.g. x86_64
+// "type": - the image type, e.g. ami, or qcow?
+// "bootmode": - the bootmode, e.g. "legacy", "uefi", "hybrid"
+func newFilter(sl ...string) (*filter, error) {
+	filter := &filter{
+		terms: make([]term, len(sl)),
+	}
+	for i, s := range sl {
+		prefix, searchTerm := splitPrefixSearchTerm(s)
+		if !slices.Contains(supportedFilters, prefix) {
+			return nil, fmt.Errorf("unsupported filter prefix: %q", prefix)
+		}
+		gl, err := glob.Compile(searchTerm)
+		if err != nil {
+			return nil, err
+		}
+		filter.terms[i].prefix = prefix
+		filter.terms[i].pattern = gl
+	}
+	return filter, nil
+}
+
+var supportedFilters = []string{
+	"", "distro", "arch", "type", "bootmode",
+}
+
+type term struct {
+	prefix  string
+	pattern glob.Glob
+}
+
+// filter provides a way to filter a list of image defintions for the
+// given filter terms.
+type filter struct {
+	terms []term
+}
+
+// Matches returns true if the given (distro,arch,imgType) tuple matches
+// the filter expressions
+func (fl filter) Matches(distro distro.Distro, arch distro.Arch, imgType distro.ImageType) bool {
+	m := true
+	for _, term := range fl.terms {
+		switch term.prefix {
+		case "":
+			// no prefix, do a "fuzzy" search accross the common
+			// things users may want
+			m1 := term.pattern.Match(distro.Name())
+			m2 := term.pattern.Match(arch.Name())
+			m3 := term.pattern.Match(imgType.Name())
+			m = m && (m1 || m2 || m3)
+		case "distro":
+			m = m && term.pattern.Match(distro.Name())
+		case "arch":
+			m = m && term.pattern.Match(arch.Name())
+		case "type":
+			m = m && term.pattern.Match(imgType.Name())
+			// mostly here to show how flexible this is
+		case "bootmode":
+			m = m && term.pattern.Match(imgType.BootMode().String())
+		}
+	}
+	return m
+}

pkg/imagefilter/filter_test.go

@@ -0,0 +1,63 @@
+package imagefilter
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/osbuild/images/pkg/distrofactory"
+)
+
+func TestImageFilterFilter(t *testing.T) {
+	fac := distrofactory.NewTestDefault()
+
+	for _, tc := range []struct {
+		searchExpr            []string
+		distro, arch, imgType string
+		expectsMatch          bool
+	}{
+		// no prefix is a "fuzzy" filter and will check distro/arch/imgType
+		{[]string{"foo"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"test-distro-1"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"test-distro*"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"test_arch3"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"qcow2"}, "test-distro-1", "test_arch3", "qcow2", true},
+		// distro: prefix (exact matches only)
+		{[]string{"distro:bar"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"distro:test-distro-1"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"distro:test-distro"}, "test-distro-1", "test_arch3", "qcow2", false},
+		// arch: prefix
+		{[]string{"arch:amd64"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"arch:test_arch3"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"arch:test_ar"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"arch:test_ar*"}, "test-distro-1", "test_arch3", "qcow2", true},
+		// type: prefix
+		{[]string{"type:ami"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"type:qcow2"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"type:qcow"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"type:qcow?"}, "test-distro-1", "test_arch3", "qcow2", true},
+		// bootmode: prefix
+		{[]string{"bootmode:uefi"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"bootmode:hybrid"}, "test-distro-1", "test_arch3", "qcow2", true},
+		// multiple filters are AND
+		{[]string{"distro:test-distro-1", "type:ami"}, "test-distro-1", "test_arch3", "qcow2", false},
+		{[]string{"distro:test-distro-1", "type:qcow2"}, "test-distro-1", "test_arch3", "qcow2", true},
+		{[]string{"distro:test-distro-1", "arch:amd64", "type:qcow2"}, "test-distro-1", "test_arch3", "qcow2", false},
+	} {
+		// XXX: it would be nice if TestDistro would support constructing
+		// like GetDistro("rhel-8.1:i386,amd64:ami,qcow2") instead of
+		// the current very static setup
+		di := fac.GetDistro(tc.distro)
+		require.NotNil(t, di)
+		ar, err := di.GetArch(tc.arch)
+		require.NoError(t, err)
+		im, err := ar.GetImageType(tc.imgType)
+		require.NoError(t, err)
+		ff, err := newFilter(tc.searchExpr...)
+		require.NoError(t, err)
+
+		match := ff.Matches(di, ar, im)
+		assert.Equal(t, tc.expectsMatch, match, tc)
+	}
+}

pkg/imagefilter/imagefilter.go

@@ -0,0 +1,90 @@
+package imagefilter
+
+import (
+	"fmt"
+
+	"github.com/osbuild/images/pkg/distro"
+	"github.com/osbuild/images/pkg/distrofactory"
+	"github.com/osbuild/images/pkg/distrosort"
+)
+
+type DistroLister interface {
+	ListDistros() []string
+}
+
+// Result contains a result from a imagefilter.Filter run
+type Result struct {
+	Distro  distro.Distro
+	Arch    distro.Arch
+	ImgType distro.ImageType
+}
+
+// ImageFilter is an a flexible way to filter the available images.
+type ImageFilter struct {
+	fac   *distrofactory.Factory
+	repos DistroLister
+}
+
+// New creates a new ImageFilter that can be used to filter the list
+// of available images
+func New(fac *distrofactory.Factory, repos DistroLister) (*ImageFilter, error) {
+	if fac == nil {
+		return nil, fmt.Errorf("cannot create ImageFilter without a valid distrofactory")
+	}
+	if repos == nil {
+		return nil, fmt.Errorf("cannot create ImageFilter without a valid reporegistry")
+	}
+
+	return &ImageFilter{fac: fac, repos: repos}, nil
+}
+
+// Filter filters the available images for the given
+// distrofactory/reporegistry based on the given filter terms. Glob
+// like patterns (?, *) are supported, see fnmatch(3).
+//
+// Without a prefix in the filter term a simple name filtering is performed.
+// With a prefix the specified property is filtered, e.g. "arch:i386". Adding
+// filtering will narrow down the filtering (terms are combined via AND).
+//
+// The following prefixes are supported:
+// "distro:" - the distro name, e.g. rhel-9, or fedora*
+// "arch:" - the architecture, e.g. x86_64
+// "type": - the image type, e.g. ami, or qcow?
+// "bootmode": - the bootmode, e.g. "legacy", "uefi", "hybrid"
+func (i *ImageFilter) Filter(searchTerms ...string) ([]Result, error) {
+	var res []Result
+
+	distroNames := i.repos.ListDistros()
+	filter, err := newFilter(searchTerms...)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := distrosort.Names(distroNames); err != nil {
+		return nil, err
+	}
+	for _, distroName := range distroNames {
+		distro := i.fac.GetDistro(distroName)
+		if distro == nil {
+			// XXX: log here?
+			continue
+		}
+		for _, archName := range distro.ListArches() {
+			a, err := distro.GetArch(archName)
+			if err != nil {
+				return nil, err
+			}
+			for _, imgTypeName := range a.ListImageTypes() {
+				imgType, err := a.GetImageType(imgTypeName)
+				if err != nil {
+					return nil, err
+				}
+				if filter.Matches(distro, a, imgType) {
+					res = append(res, Result{distro, a, imgType})
+				}
+			}
+		}
+	}
+
+	return res, nil
+}

pkg/imagefilter/imagefilter_test.go

@@ -0,0 +1,76 @@
+package imagefilter_test
+
+import (
+	"testing"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/osbuild/images/pkg/distrofactory"
+	"github.com/osbuild/images/pkg/imagefilter"
+	"github.com/osbuild/images/pkg/reporegistry"
+)
+
+func TestImageFilterSmoke(t *testing.T) {
+	logrus.SetLevel(logrus.WarnLevel)
+
+	fac := distrofactory.NewDefault()
+	repos, err := reporegistry.NewTestedDefault()
+	require.NoError(t, err)
+
+	imgFilter, err := imagefilter.New(fac, repos)
+	require.NoError(t, err)
+	res, err := imgFilter.Filter("*")
+	require.NoError(t, err)
+	assert.True(t, len(res) > 0)
+}
+
+func TestImageFilterFilter(t *testing.T) {
+	fac := distrofactory.NewDefault()
+	repos, err := reporegistry.NewTestedDefault()
+	require.NoError(t, err)
+
+	imgFilter, err := imagefilter.New(fac, repos)
+	require.NoError(t, err)
+
+	for _, tc := range []struct {
+		searchExpr   []string
+		expectsMatch bool
+	}{
+		// no prefix is a "fuzzy" filter and will check distro/arch/imgType
+		{[]string{"foo"}, false},
+		{[]string{"rhel-9.1"}, true},
+		{[]string{"rhel*"}, true},
+		{[]string{"x86_64"}, true},
+		{[]string{"qcow2"}, true},
+		// distro: prefix
+		{[]string{"distro:foo"}, false},
+		{[]string{"distro:centos-9"}, true},
+		{[]string{"distro:centos*"}, true},
+		{[]string{"distro:centos"}, false},
+		// arch: prefix
+		{[]string{"arch:foo"}, false},
+		{[]string{"arch:x86_64"}, true},
+		{[]string{"arch:x86*"}, true},
+		{[]string{"arch:x86"}, false},
+		// type: prefix
+		{[]string{"type:foo"}, false},
+		{[]string{"type:qcow2"}, true},
+		{[]string{"type:qcow?"}, true},
+		{[]string{"type:qcow"}, false},
+		// bootmode: prefix
+		{[]string{"bootmode:foo"}, false},
+		{[]string{"bootmode:hybrid"}, true},
+		// multiple filters are AND
+		{[]string{"distro:centos-9", "type:foo"}, false},
+		{[]string{"distro:centos-9", "type:qcow2"}, true},
+		{[]string{"distro:centos-9", "arch:foo", "type:qcow2"}, false},
+	} {
+
+		matches, err := imgFilter.Filter(tc.searchExpr...)
+		assert.NoError(t, err)
+		assert.Equal(t, tc.expectsMatch, len(matches) > 0, tc)
+	}
+}