mirror of
https://github.com/genuinetools/reg.git
synced 2024-07-04 12:34:17 -04:00
107 lines
5 KiB
Markdown
107 lines
5 KiB
Markdown
# OCI Image Manifest Specification
|
|
|
|
There are three main goals of the Image Manifest Specification.
|
|
The first goal is content-addressable images, by supporting an image model where the image's configuration can be hashed to generate a unique ID for the image and its components.
|
|
The second goal is to allow multi-architecture images, through a "fat manifest" which references image manifests for platform-specific versions of an image.
|
|
In OCI, this is codified in an [image index](image-index.md).
|
|
The third goal is to be [translatable](conversion.md) to the [OCI Runtime Specification](https://github.com/opencontainers/runtime-spec).
|
|
|
|
This section defines the `application/vnd.oci.image.manifest.v1+json` [media type](media-types.md).
|
|
For the media type(s) that this is compatible with see the [matrix](media-types.md#compatibility-matrix).
|
|
|
|
# Image Manifest
|
|
|
|
Unlike the [image index](image-index.md), which contains information about a set of images that can span a variety of architectures and operating systems, an image manifest provides a configuration and set of layers for a single container image for a specific architecture and operating system.
|
|
|
|
## *Image Manifest* Property Descriptions
|
|
|
|
- **`schemaVersion`** *int*
|
|
|
|
This REQUIRED property specifies the image manifest schema version.
|
|
For this version of the specification, this MUST be `2` to ensure backward compatibility with older versions of Docker. The value of this field will not change. This field MAY be removed in a future version of the specification.
|
|
|
|
- **`mediaType`** *string*
|
|
|
|
This property is *reserved* for use, to [maintain compatibility](media-types.md#compatibility-matrix).
|
|
When used, this field contains the media type of this document, which differs from the [descriptor](descriptor.md#properties) use of `mediaType`.
|
|
|
|
- **`config`** *[descriptor](descriptor.md)*
|
|
|
|
This REQUIRED property references a configuration object for a container, by digest.
|
|
Beyond the [descriptor requirements](descriptor.md#properties), the value has the following additional restrictions:
|
|
|
|
- **`mediaType`** *string*
|
|
|
|
This [descriptor property](descriptor.md#properties) has additional restrictions for `config`.
|
|
Implementations MUST support at least the following media types:
|
|
|
|
- [`application/vnd.oci.image.config.v1+json`](config.md)
|
|
|
|
Manifests concerned with portability SHOULD use one of the above media types.
|
|
|
|
- **`layers`** *array of objects*
|
|
|
|
Each item in the array MUST be a [descriptor](descriptor.md).
|
|
The array MUST have the base layer at index 0.
|
|
Subsequent layers MUST then follow in stack order (i.e. from `layers[0]` to `layers[len(layers)-1]`).
|
|
The final filesystem layout MUST match the result of [applying](layer.md#applying-changesets) the layers to an empty directory.
|
|
The [ownership, mode, and other attributes](layer.md#file-attributes) of the initial empty directory are unspecified.
|
|
|
|
Beyond the [descriptor requirements](descriptor.md#properties), the value has the following additional restrictions:
|
|
|
|
- **`mediaType`** *string*
|
|
|
|
This [descriptor property](descriptor.md#properties) has additional restrictions for `layers[]`.
|
|
Implementations MUST support at least the following media types:
|
|
|
|
- [`application/vnd.oci.image.layer.v1.tar`](layer.md)
|
|
- [`application/vnd.oci.image.layer.v1.tar+gzip`](layer.md#gzip-media-types)
|
|
- [`application/vnd.oci.image.layer.nondistributable.v1.tar`](layer.md#non-distributable-layers)
|
|
- [`application/vnd.oci.image.layer.nondistributable.v1.tar+gzip`](layer.md#gzip-media-types)
|
|
|
|
Manifests concerned with portability SHOULD use one of the above media types.
|
|
|
|
Entries in this field will frequently use the `+gzip` types.
|
|
|
|
- **`annotations`** *string-string map*
|
|
|
|
This OPTIONAL property contains arbitrary metadata for the image manifest.
|
|
This OPTIONAL property MUST use the [annotation rules](annotations.md#rules).
|
|
|
|
See [Pre-Defined Annotation Keys](annotations.md#pre-defined-annotation-keys).
|
|
|
|
## Example Image Manifest
|
|
|
|
*Example showing an image manifest:*
|
|
```json,title=Manifest&mediatype=application/vnd.oci.image.manifest.v1%2Bjson
|
|
{
|
|
"schemaVersion": 2,
|
|
"config": {
|
|
"mediaType": "application/vnd.oci.image.config.v1+json",
|
|
"size": 7023,
|
|
"digest": "sha256:b5b2b2c507a0944348e0303114d8d93aaaa081732b86451d9bce1f432a537bc7"
|
|
},
|
|
"layers": [
|
|
{
|
|
"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
|
|
"size": 32654,
|
|
"digest": "sha256:9834876dcfb05cb167a5c24953eba58c4ac89b1adf57f28f2f9d09af107ee8f0"
|
|
},
|
|
{
|
|
"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
|
|
"size": 16724,
|
|
"digest": "sha256:3c3a4604a545cdc127456d94e421cd355bca5b528f4a9c1905b15da2eb4a4c6b"
|
|
},
|
|
{
|
|
"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
|
|
"size": 73109,
|
|
"digest": "sha256:ec4b8955958665577945c89419d1af06b5f7636b4ac3da7f12184802ad867736"
|
|
}
|
|
],
|
|
"annotations": {
|
|
"com.example.key1": "value1",
|
|
"com.example.key2": "value2"
|
|
}
|
|
}
|
|
```
|