podman images: sort repository with tags

When you sort by repository a user most likely also want the tags to be
sorted as well. At the very least to get a stable output as the order
could be changed pull podman tag/pull even if they keep using the same
tag name.

Fixes #23803

Signed-off-by: Paul Holzinger <[email protected]>

cmd/podman/images/list.go

@@ -1,10 +1,11 @@
 package images
 
 import (
+	"cmp"
 	"errors"
 	"fmt"
 	"os"
-	"sort"
+	"slices"
 	"strings"
 	"time"
 	"unicode"
@@ -249,7 +250,35 @@ func sortImages(imageS []*entities.ImageSummary) ([]imageReporter, error) {
 		listFlag.readOnly = e.IsReadOnly()
 	}
 
-	sort.Slice(imgs, sortFunc(listFlag.sort, imgs))
+	slices.SortFunc(imgs, func(a, b imageReporter) int {
+		switch listFlag.sort {
+		case "id":
+			return cmp.Compare(a.ID(), b.ID())
+
+		case "repository":
+			r := cmp.Compare(a.Repository, b.Repository)
+			if r == 0 {
+				// if repository is the same imply tag sorting
+				return cmp.Compare(a.Tag, b.Tag)
+			}
+			return r
+		case "size":
+			return cmp.Compare(a.size(), b.size())
+		case "tag":
+			return cmp.Compare(a.Tag, b.Tag)
+		case "created":
+			if a.created().After(b.created()) {
+				return -1
+			}
+			if a.created().Equal(b.created()) {
+				return 0
+			}
+			return 1
+		default:
+			return 0
+		}
+	})
+
 	return imgs, err
 }
 
@@ -284,32 +313,6 @@ func tokenRepoTag(ref string) (string, string, error) {
 	return name, tag, nil
 }
 
-func sortFunc(key string, data []imageReporter) func(i, j int) bool {
-	switch key {
-	case "id":
-		return func(i, j int) bool {
-			return data[i].ID() < data[j].ID()
-		}
-	case "repository":
-		return func(i, j int) bool {
-			return data[i].Repository < data[j].Repository
-		}
-	case "size":
-		return func(i, j int) bool {
-			return data[i].size() < data[j].size()
-		}
-	case "tag":
-		return func(i, j int) bool {
-			return data[i].Tag < data[j].Tag
-		}
-	default:
-		// case "created":
-		return func(i, j int) bool {
-			return data[i].created().After(data[j].created())
-		}
-	}
-}
-
 func lsFormatFromFlags(flags listFlagType) string {
 	row := []string{
 		"{{if .Repository}}{{.Repository}}{{else}}<none>{{end}}",

docs/source/markdown/podman-images.1.md.in

@@ -119,6 +119,7 @@ Lists only the image IDs.
 #### **--sort**=*sort*
 
 Sort by *created*, *id*, *repository*, *size* or *tag* (default: **created**)
+When sorting by *repository* it also sorts by the *tag* as second criteria to provide a stable output.
 
 ## EXAMPLE
 

test/system/020-tag.bats

@@ -27,6 +27,25 @@ function _tag_and_check() {
     # prepended and ":latest" is appended.
     _tag_and_check image localhost/image:latest
 
+    # The order is intentionally wrong here to check the sorting
+    # https://github.com/containers/podman/issues/23803
+    local image1="registry.com/image:1"
+    run_podman tag $IMAGE $image1
+    local image3="registry.com/image:3"
+    run_podman tag $IMAGE $image3
+    local image2="registry.com/image:2"
+    run_podman tag $IMAGE $image2
+
+    local imageA="registry.com/aaa:a"
+    run_podman tag $IMAGE $imageA
+
+    local nl="
+"
+    run_podman images --format '{{.Repository}}:{{.Tag}}' --sort repository
+    assert "$output" =~ "$imageA${nl}$image1${nl}$image2${nl}$image3" "images are sorted by repository and tag"
+
+    run_podman untag $IMAGE $imageA $image1 $image2 $image3
+
     # Test error case.
     run_podman 125 untag $IMAGE registry.com/foo:bar
     is "$output" "Error: registry.com/foo:bar: tag not known"