Support bare Image ID lookup in local image cache

Author: konstantinosGkilas

core/src/main/java/org/testcontainers/images/LocalImagesCache.java

@@ -97,8 +97,13 @@ private void populateFromList(List<Image> images) {
                     });
             }
 
-            if (repoTags == null && repoDigests == null) {
-                log.debug("repoTags and repoDigests are both null, skipping image: {}", image);
+            String id = image.getId();
+            if (id != null) {
+                cache.put(new DockerImageName(id), imageData);
+            }
+
+            if (repoTags == null && repoDigests == null && id == null) {
+                log.debug("repoTags, repoDigests, and id are all null, skipping image: {}", image);
             }
         }
     }

core/src/test/java/org/testcontainers/images/LocalImagesCacheTest.java

@@ -67,8 +67,8 @@ void shouldCacheImageByBothTagAndDigest() {
     }
 
     @Test
-    void shouldSkipImageWithNullTagsAndNullDigests() {
-        Image image = createImage(null, null, "sha256:ddd444", 1000L);
+    void shouldSkipImageWithNullTagsAndNullDigestsAndNullId() {
+        Image image = createImage(null, null, null, 1000L);
 
         populateCache(image);
 
@@ -110,6 +110,42 @@ void shouldHandleDuplicateRepoTags() {
         assertThat(LocalImagesCache.INSTANCE.cache).containsKey(new DockerImageName("alpine:3.17"));
     }
 
+    @Test
+    void shouldCacheImageById() {
+        Image image = createImage(
+            new String[] { "alpine:3.17" },
+            null,
+            "sha256:8cf620617c6203b24af7c5bf15a7212386c27ad008fc4c6ff7e37a1bf0a3cdd2",
+            1000L
+        );
+
+        populateCache(image);
+
+        assertThat(LocalImagesCache.INSTANCE.cache)
+            .containsKey(new DockerImageName("alpine:3.17"))
+            .containsKey(
+                new DockerImageName("sha256:8cf620617c6203b24af7c5bf15a7212386c27ad008fc4c6ff7e37a1bf0a3cdd2")
+            );
+    }
+
+    @Test
+    void shouldCacheImageByIdWhenNoTagsOrDigests() {
+        Image image = createImage(
+            null,
+            null,
+            "sha256:8cf620617c6203b24af7c5bf15a7212386c27ad008fc4c6ff7e37a1bf0a3cdd2",
+            1000L
+        );
+
+        populateCache(image);
+
+        assertThat(LocalImagesCache.INSTANCE.cache)
+            .hasSize(1)
+            .containsKey(
+                new DockerImageName("sha256:8cf620617c6203b24af7c5bf15a7212386c27ad008fc4c6ff7e37a1bf0a3cdd2")
+            );
+    }
+
     @Test
     void shouldCacheDigestOnlyImageWithoutTags() {
         Image image = createImage(