Merge pull request #51072 from thaJeztah/image_inspect_omit_legacy

api: omit legacy fields from image inspect if not set

api/docs/CHANGELOG.md

@@ -34,6 +34,12 @@ keywords: "API, Docker, rcli, REST, documentation"
 * `GET /images/{name}/json` now omits the following `Config` fields when
   not set, to closer align with the implementation of the [OCI Image Specification](https://github.com/opencontainers/image-spec/blob/v1.1.1/specs-go/v1/config.go#L23-L62)
   `Cmd`, `Entrypoint`, `Env`, `Labels`, `OnBuild`, `User`, `Volumes`, and `WorkingDir`.
+* `GET /images/{name}/json` now omits the following fields if their value
+  is empty: `Parent`, `Comment`, `DockerVersion`, `Author`. The `Parent`
+  and `DockerVersion` fields were set by the legacy builder, and are no
+  longer set when using BuildKit. The `Author` field is set through the
+  `MAINTAINER` Dockerfile instruction, which is deprecated, and the `Comment`
+  field is option, and may not be set depending on how the image was created.
 * `GET /containers/{id}/json`: the `NetworkSettings` no longer returns the deprecated
   `Bridge`, `HairpinMode`, `LinkLocalIPv6Address`, `LinkLocalIPv6PrefixLen`,
   `SecondaryIPAddresses`, `SecondaryIPv6Addresses`, `EndpointID`, `Gateway`,

api/docs/v1.52.yaml

@@ -1839,13 +1839,13 @@ definitions:
           is only set for images that were built/created locally. This field
           is empty if the image was pulled from an image registry.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Comment:
         description: |
           Optional message that was set when committing or importing the image.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Created:
         description: |
@@ -1864,14 +1864,14 @@ definitions:
 
           Depending on how the image was created, this field may be empty.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: "27.0.1"
       Author:
         description: |
           Name of the author that was specified when committing the image, or as
           specified through MAINTAINER (deprecated) in the Dockerfile.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Config:
         $ref: "#/definitions/ImageConfig"

api/swagger.yaml

@@ -1839,13 +1839,13 @@ definitions:
           is only set for images that were built/created locally. This field
           is empty if the image was pulled from an image registry.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Comment:
         description: |
           Optional message that was set when committing or importing the image.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Created:
         description: |
@@ -1864,14 +1864,14 @@ definitions:
 
           Depending on how the image was created, this field may be empty.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: "27.0.1"
       Author:
         description: |
           Name of the author that was specified when committing the image, or as
           specified through MAINTAINER (deprecated) in the Dockerfile.
         type: "string"
-        x-nullable: false
+        x-nullable: true
         example: ""
       Config:
         $ref: "#/definitions/ImageConfig"

api/types/image/image_inspect.go

@@ -47,12 +47,12 @@ type InspectResponse struct {
 	//
 	// Depending on how the image was created, this field may be empty and
 	// is only set for images that were built/created locally. This field
-	// is empty if the image was pulled from an image registry.
-	Parent string
+	// is omitted if the image was pulled from an image registry.
+	Parent string `json:",omitempty"`
 
 	// Comment is an optional message that can be set when committing or
-	// importing the image.
-	Comment string
+	// importing the image. This field is omitted if not set.
+	Comment string `json:",omitempty"`
 
 	// Created is the date and time at which the image was created, formatted in
 	// RFC 3339 nano-seconds (time.RFC3339Nano).
@@ -79,12 +79,13 @@ type InspectResponse struct {
 
 	// DockerVersion is the version of Docker that was used to build the image.
 	//
-	// Depending on how the image was created, this field may be empty.
-	DockerVersion string
+	// Depending on how the image was created, this field may be omitted.
+	DockerVersion string `json:",omitempty"`
 
 	// Author is the name of the author that was specified when committing the
 	// image, or as specified through MAINTAINER (deprecated) in the Dockerfile.
-	Author string
+	// This field is omitted if not set.
+	Author string `json:",omitempty"`
 	Config *dockerspec.DockerOCIImageConfig
 
 	// Architecture is the hardware CPU architecture that the image runs on.

daemon/server/router/image/image_routes.go

@@ -418,6 +418,14 @@ func (ir *imageRouter) getImagesByName(ctx context.Context, w http.ResponseWrite
 		imageInspect.Descriptor = nil
 	}
 	if versions.LessThan(version, "1.52") {
+		// These fields have "omitempty" on API v1.52 and higher,
+		// but older API versions returned them unconditionally.
+		legacyOptions = append(legacyOptions, compat.WithExtraFields(map[string]any{
+			"Parent":        imageInspect.Parent,
+			"Comment":       imageInspect.Comment,
+			"DockerVersion": imageInspect.DockerVersion,
+			"Author":        imageInspect.Author,
+		}))
 		if versions.LessThan(version, "1.50") {
 			legacyOptions = append(legacyOptions, compat.WithExtraFields(legacyConfigFields["v1.49"]))
 		} else {

vendor/github.com/moby/moby/api/types/image/image_inspect.go

@@ -47,12 +47,12 @@ type InspectResponse struct {
 	//
 	// Depending on how the image was created, this field may be empty and
 	// is only set for images that were built/created locally. This field
-	// is empty if the image was pulled from an image registry.
-	Parent string
+	// is omitted if the image was pulled from an image registry.
+	Parent string `json:",omitempty"`
 
 	// Comment is an optional message that can be set when committing or
-	// importing the image.
-	Comment string
+	// importing the image. This field is omitted if not set.
+	Comment string `json:",omitempty"`
 
 	// Created is the date and time at which the image was created, formatted in
 	// RFC 3339 nano-seconds (time.RFC3339Nano).
@@ -79,12 +79,13 @@ type InspectResponse struct {
 
 	// DockerVersion is the version of Docker that was used to build the image.
 	//
-	// Depending on how the image was created, this field may be empty.
-	DockerVersion string
+	// Depending on how the image was created, this field may be omitted.
+	DockerVersion string `json:",omitempty"`
 
 	// Author is the name of the author that was specified when committing the
 	// image, or as specified through MAINTAINER (deprecated) in the Dockerfile.
-	Author string
+	// This field is omitted if not set.
+	Author string `json:",omitempty"`
 	Config *dockerspec.DockerOCIImageConfig
 
 	// Architecture is the hardware CPU architecture that the image runs on.