Fixes #12063 Add docker compatible output after image build.

Signed-off-by: Ananth Bhaskararaman <antsub@gmail.com>

pkg/api/handlers/compat/images_build.go

@@ -621,7 +621,8 @@ func BuildImage(w http.ResponseWriter, r *http.Request) {
 			Stream string                 `json:"stream,omitempty"`
 			Error  *jsonmessage.JSONError `json:"errorDetail,omitempty"`
 			// NOTE: `error` is being deprecated check https://github.com/moby/moby/blob/master/pkg/jsonmessage/jsonmessage.go#L148
-			ErrorMessage string `json:"error,omitempty"` // deprecate this slowly
+			ErrorMessage string          `json:"error,omitempty"` // deprecate this slowly
+			Aux          json.RawMessage `json:"aux,omitempty"`
 		}{}
 
 		select {
@@ -656,6 +657,11 @@ func BuildImage(w http.ResponseWriter, r *http.Request) {
 		case <-runCtx.Done():
 			if success {
 				if !utils.IsLibpodRequest(r) && !query.Quiet {
+					m.Aux = []byte(fmt.Sprintf(`{"ID":"sha256:%s"}`, imageID))
+					if err := enc.Encode(m); err != nil {
+						logrus.Warnf("failed to json encode error %v", err)
+					}
+					m.Aux = nil
 					m.Stream = fmt.Sprintf("Successfully built %12.12s\n", imageID)
 					if err := enc.Encode(m); err != nil {
 						logrus.Warnf("Failed to json encode error %v", err)

test/apiv2/10-images.at

@@ -229,6 +229,20 @@ if ! grep -q '400 Bad Request' "${TMPD}/headers.txt"; then
     BUILD_TEST_ERROR="1"
 fi
 
+curl -XPOST --data-binary @<(cat $CONTAINERFILE_TAR) \
+    -H "content-type: application/tar" \
+    --dump-header "${TMPD}/headers.txt" \
+    -o "${TMPD}/response.txt" \
+    "http://$HOST:$PORT/v1.40/build?dockerfile=containerfile" &> /dev/null
+if ! grep -q '200 OK' "${TMPD}/headers.txt"; then
+    echo -e "${red}NOK: Image build from tar failed response was not 200 OK (application/tar)"
+    BUILD_TEST_ERROR="1"
+fi
+if ! grep -qP '^{"aux":{"ID":"sha256:[0-9a-f]{64}"}}$' "${TMPD}/response.txt"; then
+    echo -e "${red}NOK: Image build response does not contain ID"
+    BUILD_TEST_ERROR="1"
+fi
+
 t POST libpod/images/prune 200
 t POST libpod/images/prune 200 length=0 []