compat: RepoTags and RepoDigest return [] and not null

Signed-off-by: Nicola Sella <[email protected]>

Author: inknos

pkg/api/handlers/compat/images.go

@@ -496,6 +496,15 @@ func GetImages(w http.ResponseWriter, r *http.Request) {
 		// docker adds sha256: in front of the ID
 		for _, s := range summaries {
 			s.ID = "sha256:" + s.ID
+			// Ensure RepoTags and RepoDigests are empty arrays instead of null for Docker compatibility
+			// as per https://docs.docker.com/reference/api/engine/version-history/#v143-api-changes
+			// Relates to https://issues.redhat.com/browse/RUN-2699
+			if s.RepoTags == nil {
+				s.RepoTags = []string{}
+			}
+			if s.RepoDigests == nil {
+				s.RepoDigests = []string{}
+			}
 		}
 	}
 	utils.WriteResponse(w, http.StatusOK, summaries)

test/apiv2/10-images.at

@@ -440,4 +440,19 @@ t GET "libpod/events?stream=false&since=$START"  200  \
   .Actor.Attributes.name="localhost:5000/idonotexist" \
   .Actor.Attributes.error~".*connection refused"
 
+# test empty RepoTags and RepoDigests is an empty array
+IIDFILE=$(mktemp)
+podman image build --iidfile $IIDFILE -<<EOF
+FROM $IMAGE
+RUN :
+EOF
+
+t GET images/json 200 \
+  .[2].RepoTags=[] \
+  .[2].RepoDigests=[] \
+  .[2].Id=$(< $IIDFILE)
+
+podman rmi -f $(< $IIDFILE)
+rm -f $IIDFILE
+
 # vim: filetype=sh