filters: add new getOneImage() helper for manifest/build

This commit adds a helper to find exactly a single image from a
given disto/type/arch description. This will be used in `manifest`,
`build` and potentially more. It is meant to support copy/paste
from the `image-builder list-images` output, so: "distro:centos-9"
is support just like "centos-9" (same for distro/imgType/arch).

cmd/image-builder/export_test.go

@@ -8,6 +8,10 @@ import (
 	"github.com/osbuild/images/pkg/reporegistry"
 )
 
+var (
+	GetOneImage = getOneImage
+)
+
 func MockOsArgs(new []string) (restore func()) {
 	saved := os.Args
 	os.Args = append([]string{"argv0"}, new...)

cmd/image-builder/filters.go

@@ -1,6 +1,11 @@
 package main
 
 import (
+	"fmt"
+	"strings"
+
+	"github.com/gobwas/glob"
+
 	"github.com/osbuild/images/pkg/distrofactory"
 	"github.com/osbuild/images/pkg/imagefilter"
 )
@@ -13,3 +18,45 @@ func newImageFilterDefault(dataDir string) (*imagefilter.ImageFilter, error) {
 	}
 	return imagefilter.New(fac, repos)
 }
+
+// should this be moved to images:imagefilter?
+func getOneImage(dataDir, distroName, imgTypeStr, archStr string) (*imagefilter.Result, error) {
+	imageFilter, err := newImageFilterDefault(dataDir)
+	if err != nil {
+		return nil, err
+	}
+	// strip prefixes to make ib copy/paste friendly when pasting output
+	// from "list-images"
+	distroName = strings.TrimPrefix(distroName, "distro:")
+	imgTypeStr = strings.TrimPrefix(imgTypeStr, "type:")
+	archStr = strings.TrimPrefix(archStr, "arch:")
+
+	// error early when globs are used
+	for _, s := range []string{distroName, imgTypeStr, archStr} {
+		if glob.QuoteMeta(s) != s {
+			return nil, fmt.Errorf("cannot use globs in %q when getting a single image", s)
+		}
+	}
+
+	filterExprs := []string{
+		fmt.Sprintf("distro:%s", distroName),
+		fmt.Sprintf("arch:%s", archStr),
+		fmt.Sprintf("type:%s", imgTypeStr),
+	}
+	filteredResults, err := imageFilter.Filter(filterExprs...)
+	if err != nil {
+		return nil, err
+	}
+	switch len(filteredResults) {
+	case 0:
+		return nil, fmt.Errorf("cannot find image for: distro:%q type:%q arch:%q", distroName, imgTypeStr, archStr)
+	case 1:
+		return &filteredResults[0], nil
+	default:
+		// This condition should never be hit in practise as we
+		// disallow globs above.
+		// XXX: imagefilter.Result should have a String() method so
+		// that this output can actually show the results
+		return nil, fmt.Errorf("internal error: found %v results for %q %q %q", len(filteredResults), distroName, imgTypeStr, archStr)
+	}
+}

cmd/image-builder/filters_test.go

@@ -0,0 +1,55 @@
+package main_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	testrepos "github.com/osbuild/images/test/data/repositories"
+
+	"github.com/osbuild/image-builder-cli/cmd/image-builder"
+)
+
+func TestGetOneImageHappy(t *testing.T) {
+	restore := main.MockNewRepoRegistry(testrepos.New)
+	defer restore()
+
+	dataDir := ""
+	for _, tc := range []struct {
+		distro, imgType, arch string
+	}{
+		{"centos-9", "qcow2", "x86_64"},
+		{"distro:centos-9", "qcow2", "x86_64"},
+		{"distro:centos-9", "type:qcow2", "x86_64"},
+		{"distro:centos-9", "type:qcow2", "arch:x86_64"},
+	} {
+		res, err := main.GetOneImage(dataDir, tc.distro, tc.imgType, tc.arch)
+		assert.NoError(t, err)
+		assert.Equal(t, "centos-9", res.Distro.Name())
+		assert.Equal(t, "qcow2", res.ImgType.Name())
+		assert.Equal(t, "x86_64", res.Arch.Name())
+	}
+}
+
+func TestGetOneImageError(t *testing.T) {
+	restore := main.MockNewRepoRegistry(testrepos.New)
+	defer restore()
+
+	dataDir := ""
+	for _, tc := range []struct {
+		distro, imgType, arch string
+		expectedErr           string
+	}{
+		{
+			"unknown", "qcow2", "x86_64",
+			`cannot find image for: distro:"unknown" type:"qcow2" arch:"x86_64"`,
+		},
+		{
+			"centos*", "qcow2", "x86_64",
+			`cannot use globs in "centos*" when getting a single image`,
+		},
+	} {
+		_, err := main.GetOneImage(dataDir, tc.distro, tc.imgType, tc.arch)
+		assert.EqualError(t, err, tc.expectedErr)
+	}
+}