### Example Base Layer Resources

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Illustrates the initial state of files in a base layer before modifications.

```text
file1
a/file2
b/
c/file3
```

--------------------------------

### Validate Examples

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Execute tests that validate the examples provided within the project.

```shell
make validate-examples
```

--------------------------------

### Example Layer with Opaque Whiteout

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Illustrates the use of an opaque whiteout file to remove all children of a directory.

```text
bin/
  .wh..wh..opq
```

--------------------------------

### Example OCI Image Manifest Blob

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This example shows the content of a manifest blob, which describes the image's configuration and layers. It includes media types, sizes, and digests for the configuration and layers.

```shell
$ cat ./blobs/sha256/9b97579de92b1c195b85bb42a11011378ee549b02d7fe9c17bf2a6b35d5cb079 | jq
{
  "schemaVersion": 2,
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 7143,
      "digest": "sha256:afff3924849e458c5ef237db5f89539274d5e609db5db935ed3959c90f1f2d51",
      "platform": {
        "architecture": "ppc64le",
        "os": "linux"
      }
    },
...
```

--------------------------------

### Example OCI Image Manifest Blob (Config and Layers)

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This example displays the content of an OCI image manifest, detailing the configuration and layer information. It specifies the media type, size, and digest for the image configuration and its layers.

```shell
$ cat ./blobs/sha256/afff3924849e458c5ef237db5f89539274d5e609db5db935ed3959c90f1f2d51 | jq
{
  "schemaVersion": 2,
  "config": {
    "mediaType": "application/vnd.oci.image.config.v1+json",
    "size": 7023,
    "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270"
  },
  "layers": [
    {
      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
      "size": 32654,
      "digest": "sha256:9834876dcfb05cb167a5c24953eba58c4ac89b1adf57f28f2f9d09af107ee8f0"
    },
...
```

--------------------------------

### Example Layer with Opaque Whiteout on Nested Directory

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Shows a layer where an opaque whiteout is applied to 'a/', followed by the recreation of 'a/b/c/foo'.

```text
a/
a/.wh..wh..opq
a/b/
a/b/c/
a/b/c/foo
```

--------------------------------

### Example Base Layer for Opaque Whiteout

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Demonstrates a base layer structure to illustrate the application of opaque whiteouts.

```text
etc/
  my-app-config
bin/
  my-app-binary
  my-app-tools
  tools/
    my-app-tool-one
```

--------------------------------

### Example Base Layer for Opaque Whiteout on Nested Directory

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Provides a base layer with nested directories to demonstrate opaque whiteout on a parent directory.

```text
a/
a/b/
a/b/c/
a/b/c/bar
```

--------------------------------

### Initial Empty Directory Structure

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Represents the starting point of a layer's root filesystem as an empty directory. This serves as a baseline for tracking changes.

```text
rootfs-c9d-v1/

```

--------------------------------

### Example OCI Image Configuration JSON

Source: https://github.com/opencontainers/image-spec/blob/main/config.md

This JSON document represents a typical configuration for an OCI image, detailing its creation metadata, runtime settings, and filesystem history.

```json
{
    "created": "2015-10-31T22:22:56.015925234Z",
    "author": "Alyssa P. Hacker <alyspdev@example.com>",
    "architecture": "amd64",
    "os": "linux",
    "config": {
        "User": "alice",
        "ExposedPorts": {
            "8080/tcp": {}
        },
        "Env": [
            "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
            "FOO=oci_is_a",
            "BAR=well_written_spec"
        ],
        "Entrypoint": [
            "/bin/my-app-binary"
        ],
        "Cmd": [
            "--foreground",
            "--config",
            "/etc/my-app.d/default.cfg"
        ],
        "Volumes": {
            "/var/job-result-data": {},
            "/var/log/my-app-logs": {}
        },
        "WorkingDir": "/home/alice",
        "Labels": {
            "com.example.project.git.url": "https://example.com/project.git",
            "com.example.project.git.commit": "45a939b2999782a3f005621a8d0f29aa387e1d6b"
        }
    },
    "rootfs": {
      "diff_ids": [
        "sha256:c6f988f4874bb0add23a778f753c65efe992244e148a1d2ec2a8b664fb66bbd1",
        "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef"
      ],
      "type": "layers"
    },
    "history": [
      {
        "created": "2015-10-31T22:22:54.690851953Z",
        "created_by": "/bin/sh -c #(nop) ADD file:a3bc1e842b69636f9df5256c49c5374fb4eef1e281fe3f282c65fb853ee171c5 in /"
      },
      {
        "created": "2015-10-31T22:22:55.613815829Z",
        "created_by": "/bin/sh -c #(nop) CMD [\"sh\"]",
        "empty_layer": true
      },
      {
        "created": "2015-10-31T22:22:56.329850019Z",
        "created_by": "/bin/sh -c apk add curl"
      }
    ]
}
```

--------------------------------

### ImageID Format Example

Source: https://github.com/opencontainers/image-spec/blob/main/config.md

Provides an example of the ImageID format, which is a SHA256 hash of the image's configuration JSON. This format ensures that images are content-addressable.

```text
sha256:a9561eb1b190625c9adb5a9513e72c4dedafc1cb2d4c5236c9a6957ec7dfd5a9
```

--------------------------------

### OCI Image Manifest Example

Source: https://github.com/opencontainers/image-spec/blob/main/manifest.md

An example of an OCI image manifest, which describes the layers and configuration of a container image. It includes digests and sizes for the image configuration and its layers, as well as optional subject and annotation fields.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "config": {
    "mediaType": "application/vnd.oci.image.config.v1+json",
    "digest": "sha256:b5b2b2c507a0944348e0303114d8d93aaaa081732b86451d9bce1f432a537bc7",
    "size": 7023
  },
  "layers": [
    {
      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
      "digest": "sha256:9834876dcfb05cb167a5c24953eba58c4ac89b1adf57f28f2f9d09af107ee8f0",
      "size": 32654
    },
    {
      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
      "digest": "sha256:3c3a4604a545cdc127456d94e421cd355bca5b528f4a9c1905b15da2eb4a4c6b",
      "size": 16724
    },
    {
      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
      "digest": "sha256:ec4b8955958665577945c89419d1af06b5f7636b4ac3da7f12184802ad867736",
      "size": 73109
    }
  ],
  "subject": {
    "mediaType": "application/vnd.oci.image.manifest.v1+json",
    "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270",
    "size": 7682
  },
  "annotations": {
    "com.example.key1": "value1",
    "com.example.key2": "value2"
  }
}
```

--------------------------------

### Example OCI Image Layer Blob

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This example represents a gzipped tar stream, which is the content of an OCI image layer. It is typically a compressed archive containing the filesystem changes for that layer.

```shell
$ cat ./blobs/sha256/9834876dcfb05cb167a5c24953eba58c4ac89b1adf57f28f2f9d09af107ee8f0
[gzipped tar stream]
```

--------------------------------

### Example Layer with Explicit Whiteouts

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Shows how explicit whiteout files are used to mark paths for deletion in the next layer.

```text
.wh.file1
a/.wh.file2
.wh.b
file4
```

--------------------------------

### Example Layer with Explicit Whiteouts for Directory Deletion

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Shows the equivalent representation of an opaque whiteout using individual explicit whiteout files for each entry within a directory.

```text
bin/
  .wh.my-app-binary
  .wh.my-app-tools
  .wh.tools
```

--------------------------------

### Example OCI Image Layout Directory Structure

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This shell command shows the typical file structure of an OCI image layout directory. It includes the index.json, oci-layout file, and blobs organized by hash algorithm.

```shell
$ cd example.com/app/
$ find . -type f
./index.json
./oci-layout
./blobs/sha256/3588d02542238316759cbf24502f4344ffcc8a60c803870022f335d1390c13b4
./blobs/sha256/4b0bc1c4050b03c95ef2a8e36e25feac42fd31283e8c30b3ee5df6b043155d3c
./blobs/sha256/7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768
```

--------------------------------

### OCI Content Descriptor Example

Source: https://github.com/opencontainers/image-spec/blob/main/descriptor.md

A basic OCI content descriptor for an image manifest. It includes the media type, size, and SHA-256 digest.

```json
{
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "size": 7682,
  "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270"
}
```

--------------------------------

### OCI Image Index for Multiple Platforms

Source: https://github.com/opencontainers/image-spec/blob/main/image-index.md

An example of an OCI image index that references manifests for two different platforms (PPC64LE and AMD64). This structure is useful for distributing container images that need to run on various architectures.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.index.v1+json",
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 7143,
      "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
      "platform": {
        "architecture": "ppc64le",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 7682,
      "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270",
      "platform": {
        "architecture": "amd64",
        "os": "linux"
      }
    }
  ],
  "annotations": {
    "com.example.key1": "value1",
    "com.example.key2": "value2"
  }
}
```

--------------------------------

### OCI Image Index with Multiple Media Types

Source: https://github.com/opencontainers/image-spec/blob/main/image-index.md

An example of an OCI image index that includes manifests with different media types. This demonstrates flexibility in referencing various types of artifacts within a single index.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.index.v1+json",
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 7143,
      "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
      "platform": {
        "architecture": "ppc64le",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.index.v1+json",
      "size": 7682,
      "digest": "sha256:601570aaff1b68a61eb9c85b8beca1644e698003e0cdb5bce960f193d265a8b7"
    }
  ],
  "annotations": {
    "com.example.key1": "value1",
    "com.example.key2": "value2"
  }
}
```

--------------------------------

### OCI Layout Header Example

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This JSON object serves as the header for an OCI image layout, specifying the imageLayoutVersion. It indicates the version of the OCI Image Specification that the layout adheres to.

```json
{
    "imageLayoutVersion": "1.0.0"
}
```

--------------------------------

### OCI Image Index Example

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This JSON structure represents an OCI image index. It includes a list of manifests, each with its media type, size, digest, and optional platform and annotations. The `org.opencontainers.image.ref.name` annotation on descriptors within an index is used for named references.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.index.v1+json",
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.index.v1+json",
      "size": 7143,
      "digest": "sha256:0228f90e926ba6b96e4f39cf294b2586d38fbb5a1e385c05cd1ee40ea54fe7fd",
      "annotations": {
        "org.opencontainers.image.ref.name": "stable-release"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 7143,
      "digest": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
      "platform": {
        "architecture": "ppc64le",
        "os": "linux"
      },
      "annotations": {
        "org.opencontainers.image.ref.name": "v1.0"
      }
    },
    {
      "mediaType": "application/xml",
      "size": 7143,
      "digest": "sha256:b3d63d132d21c3ff4c35a061adf23cf43da8ae054247e32faa95494d904a007e",
      "annotations": {
        "org.freedesktop.specifications.metainfo.version": "1.0",
        "org.freedesktop.specifications.metainfo.type": "AppStream"
      }
    }
  ],
  "annotations": {
    "com.example.index.revision": "r124356"
  }
}
```

--------------------------------

### Filter Changelog Lines

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Removes lines starting with 'M', 'A', or 'D' from the changelog, which indicate commit status changes.

```vim
:%!grep -vE '(^M|^A|^D)'
```

--------------------------------

### Example OCI Image Configuration Blob

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This JSON object represents the configuration of an OCI image, including details such as architecture, author, environment variables, and the base image digest. It is essential for understanding the image's runtime environment.

```shell
$ cat ./blobs/sha256/5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270 | jq
{
  "architecture": "amd64",
  "author": "Alyssa P. Hacker <alyspdev@example.com>",
  "config": {
    "Hostname": "8dfe43d80430",
    "Domainname": "",
    "User": "",
    "AttachStdin": false,
    "AttachStdout": false,
    "AttachStderr": false,
    "Tty": false,
    "OpenStdin": false,
    "StdinOnce": false,
    "Env": [
      "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
    ],
    "Cmd": null,
    "Image": "sha256:6986ae504bbf843512d680cc959484452034965db15f75ee8bdd1b107f61500b",
...
```

--------------------------------

### OCI Empty Descriptor Example

Source: https://github.com/opencontainers/image-spec/blob/main/manifest.md

A descriptor for an artifact with no associated content, using the media type 'application/vnd.oci.empty.v1+json'. This is guidance for implementations where empty blobs are not universally supported. The 'data' field is optional and contains the base64 encoding of '{}'.

```json
{
  "mediaType": "application/vnd.oci.empty.v1+json",
  "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
  "size": 2,
  "data": "e30="
}
```

--------------------------------

### Get Date for One Week From Now

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Calculates the date one week from the current date in UTC. This is used in the release email subject line.

```bash
TZ=UTC date --date='next week'
```

--------------------------------

### Copy Filesystem Snapshot with cp

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Use `cp -a` to create an exact copy of a root filesystem, preserving file attributes. This is a common method for initializing a layer's base.

```bash
cp -a rootfs-c9d-v1/ rootfs-c9d-v1.s1/
```

--------------------------------

### Initialize Go Workspaces

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Initialize a Go workspace to manage dependencies across multiple modules, useful when developing features spanning `specs-go` and `schema` without committing changes.

```shell
go work init . schema
```

--------------------------------

### Check License Headers

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Verify that all source code files include the necessary license headers.

```shell
make check-license
```

--------------------------------

### Equivalent Layer with Opaque Whiteout (Different Order)

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Demonstrates that the order of whiteout files and new content in a layer does not affect the outcome, as the opaque whiteout is processed first.

```text
a/
a/b/
a/b/c/
a/b/c/foo
a/.wh..wh..opq
```

--------------------------------

### Execute Go Tests

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Run all Go-based tests included in the project.

```shell
make test
```

--------------------------------

### Generate Documentation

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Generate PDF and HTML versions of the OCI image specification documentation. Requires Docker.

```shell
make docs
```

--------------------------------

### Copy Filesystem Snapshot with rsync

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Use `rsync -aHAX` to create a snapshot of a root filesystem, preserving attributes, ACLs, extended attributes, and times. This is an efficient method for creating copies.

```bash
rsync -aHAX rootfs-c9d-v1/ rootfs-c9d-v1.s1/
```

--------------------------------

### Copy Filesystem Snapshot with tar

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Use `tar` to create a snapshot of a root filesystem, preserving ACLs and extended attributes. This method involves creating a new directory and piping tar archives.

```bash
mkdir rootfs-c9d-v1.s1 && tar --acls --xattrs -C rootfs-c9d-v1/ -c . | tar -C rootfs-c9d-v1.s1/ --acls --xattrs -x
```

--------------------------------

### Checkout Release Tag

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Checks out the git tag corresponding to the release version to prepare release documentation.

```bash
git checkout $version
```

--------------------------------

### Populated Initial Filesystem Structure

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Shows a populated directory structure for a layer's root filesystem, including configuration and binary files. This structure is typically archived into a tar format.

```text
rootfs-c9d-v1/
  etc/
    my-app-config
  bin/
    my-app-binary
    my-app-tools

```

--------------------------------

### Run Go Linters

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Execute `golangci-lint` to check for linting violations in the Go source code beyond standard compiler checks.

```shell
make lint
```

--------------------------------

### Create PNG Images from Dot Files

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Generate PNG image files from DOT source files located in the `img` directory. Requires Graphviz.

```shell
make img/media-types.png
```

--------------------------------

### Push Tags to Remote

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Pushes all local tags to the remote repository.

```bash
git push --tags
```

--------------------------------

### Format JSON Schema Files

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Auto-format all JSON files in the `schema` directory using the `jq` tool. Requires `jq` version 1.5 or higher.

```shell
make fmt
```

--------------------------------

### Rename Documentation Files

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Renames the generated documentation files to include the specific release version.

```bash
mv output/oci-image-spec.pdf output/oci-image-spec-$version.pdf
```

--------------------------------

### Minimal Artifact Manifest

Source: https://github.com/opencontainers/image-spec/blob/main/manifest.md

Use this manifest when the artifact consists of no files or blobs. It requires specifying `artifactType` and setting `config` and `layers` to the empty descriptor value.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "artifactType": "application/vnd.example+type",
  "config": {
    "mediaType": "application/vnd.oci.empty.v1+json",
    "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
    "size": 2
  },
  "layers": [
    {
      "mediaType": "application/vnd.oci.empty.v1+json",
      "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
      "size": 2
    }
  ],
  "annotations": {
    "oci.opencontainers.image.created": "2023-01-02T03:04:05Z",
    "com.example.data": "payload"
  }
}
```

--------------------------------

### Generate Changelog with Git Log

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Use this command to generate a raw changelog from git history between two tags. Review the output for commit impact and formatting.

```bash
git log --oneline --no-merges --decorate --name-status v1.0.1..HEAD | vim -
```

--------------------------------

### EBNF for Path and Component

Source: https://github.com/opencontainers/image-spec/blob/main/considerations.md

Defines a simple relative path name using EBNF notation. 'component' matches one or more lowercase letters, and 'path' matches one or more components separated by slashes.

```ebnf
path      ::= component ("/" component)*
component ::= [a-z]+
```

--------------------------------

### Digest Calculation Pseudocode

Source: https://github.com/opencontainers/image-spec/blob/main/descriptor.md

Illustrates the process of calculating and verifying a content digest. It shows how to derive the digest from content bytes and compare it with a reference digest.

```text
let ID(C) = Descriptor.digest
let C = <bytes>
let D = '<alg>:' + Encode(H(C))
let verified = ID(C) == D
```

```text
D == ID(C) == '<alg>:' + Encode(H(C))
```

--------------------------------

### Verifying Blob Content with SHA256

Source: https://github.com/opencontainers/image-spec/blob/main/image-layout.md

This shell command demonstrates how to verify the content of a blob file against its expected SHA256 digest. The filename in the blobs directory should match the computed hash.

```shell
$ shasum -a 256 ./blobs/sha256/afff3924849e458c5ef237db5f89539274d5e609db5db935ed3959c90f1f2d51
afff3924849e458c5ef237db5f89539274d5e609db5db935ed3959c90f1f2d51  ./blobs/sha256/afff3924849e458c5ef237db5f89539274d5e609db5db935ed3959c90f1f2d51
```

--------------------------------

### Tar Archive Entries for Populated Filesystem

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

Lists the relative path entries that would be included in a tar archive for the populated filesystem. This is how the layer's content is stored.

```text
./
./etc/
./etc/my-app-config
./bin/
./bin/my-app-binary
./bin/my-app-tools

```

--------------------------------

### Tag Release Commit

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Creates a signed git tag for the release at the specified version bump commit.

```bash
git tag -s $version $versionBumpCommit
```

--------------------------------

### Artifact Manifest With Config Blob

Source: https://github.com/opencontainers/image-spec/blob/main/manifest.md

Use this manifest for artifacts that include a configuration blob. Specify `artifactType` for tooling compatibility, define the `config` with artifact metadata, and include the artifact content in the `layers`.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "artifactType": "application/vnd.example+type",
  "config": {
    "mediaType": "application/vnd.example.config.v1+json",
    "digest": "sha256:5891b5b522d5df086d0ff0b110fbd9d21bb4fc7163af34d08286a2e846f6be03",
    "size": 123
  },
  "layers": [
    {
      "mediaType": "application/vnd.example.data.v1.tar+gzip",
      "digest": "sha256:e258d248fda94c63753607f7c4494ee0fcbe92f1a76bfdac795c9d84101eb317",
      "size": 1234
    }
  ]
}
```

--------------------------------

### Deriving Hardlinks from Directory Structure

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

This pseudocode outlines a method to identify and map hardlinks within a directory structure by comparing file inode and device information. It's useful for generating layer changesets that accurately represent hardlinked files.

```pseudocode
SET LinkMap to map[< Major:Minor String >]map[< inode integer >]< path string >
SET LinkNames to map[< src path string >]< dest path string >
FOR each path in root path
  IF path type is directory
    CONTINUE
  ENDIF
  SET filestat to stat(path)
  IF filestat num of links == 1
    CONTINUE
  ENDIF
  IF LinkMap[filestat device][filestat inode] is not empty
    SET LinkNames[path] to LinkMap[filestat device][filestat inode]
  ELSE
    SET LinkMap[filestat device][filestat inode] to path
  ENDIF
END FOR
```

--------------------------------

### Clean Build Artifacts

Source: https://github.com/opencontainers/image-spec/blob/main/HACKING.md

Remove all generated and compiled artifacts from the project.

```shell
make clean
```

--------------------------------

### Artifact Manifest Without Config Blob

Source: https://github.com/opencontainers/image-spec/blob/main/manifest.md

Use this manifest when the artifact does not require a separate configuration blob. The artifact content is included in the `layers`, and `config` is set to the empty descriptor value.

```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "artifactType": "application/vnd.example+type",
  "config": {
    "mediaType": "application/vnd.oci.empty.v1+json",
    "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
    "size": 2
  },
  "layers": [
    {
      "mediaType": "application/vnd.example+type",
      "digest": "sha256:e258d248fda94c63753607f7c4494ee0fcbe92f1a76bfdac795c9d84101eb317",
      "size": 1234
    }
  ]
}
```

--------------------------------

### Expanded ChainID Calculation

Source: https://github.com/opencontainers/image-spec/blob/main/config.md

Shows the fully expanded calculation of ChainID for layers A, B, and C, demonstrating how it resolves to a single digest based on the individual layer DiffIDs and their order.

```text
ChainID(A|B|C) = Digest(Digest(DiffID(A) + " " + DiffID(B)) + " " + DiffID(C))
```

--------------------------------

### EBNF Repetition Operators

Source: https://github.com/opencontainers/image-spec/blob/main/considerations.md

Uses postfix operators '*' and '+' to define repetition of preceding expressions. '*' allows zero or more matches, '+' requires one or more.

```ebnf
zeroormore ::= expression*
oneormore ::= expression+
```

--------------------------------

### OCI Content Descriptor with URLs

Source: https://github.com/opencontainers/image-spec/blob/main/descriptor.md

An OCI content descriptor that specifies URLs for retrieving the referenced content. This is useful when content is not directly embedded or available via a digest alone.

```json
{
  "mediaType": "application/vnd.oci.image.manifest.v1+json",
  "size": 7682,
  "digest": "sha256:5b0bcabd1ed22e9fb1310cf6c2dec7cdef19f0ad69efa1f392e94a4333501270",
  "urls": [
    "https://example.com/example-manifest"
  ]
}
```

--------------------------------

### Tar Archive Entries for Changeset

Source: https://github.com/opencontainers/image-spec/blob/main/layer.md

This represents the entries in a tar archive that signifies a changeset. It includes added files, directories, and whiteout files for deletions.

```text
./etc/my-app.d/
./etc/my-app.d/default.cfg
./bin/my-app-tools
./etc/.wh.my-app-config
```

--------------------------------

### Format Pull Request in Changelog

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

This vim command reformats lines containing pull request references to match the desired format, moving the PR number to the end.

```vim
:% s/(pr\/\(\d*\))\(.*\)/\2 (#\1)/
```

--------------------------------

### Regular Expression for Path Matching

Source: https://github.com/opencontainers/image-spec/blob/main/considerations.md

Converts the EBNF definition of a path into a regular expression. This expression matches one or more lowercase letters, optionally followed by slash-separated groups of one or more lowercase letters.

```regex
[a-z]+(?:/[a-z]+)*
```

--------------------------------

### EBNF Grouping Expression

Source: https://github.com/opencontainers/image-spec/blob/main/considerations.md

Groups multiple expressions together using parentheses. Allows operators to be applied to the entire group.

```ebnf
group ::= (A B)
```

--------------------------------

### ChainID Calculation Formula

Source: https://github.com/opencontainers/image-spec/blob/main/config.md

Illustrates the recursive definition of ChainID for a sequence of layers A, B, and C. This formula ensures that the identifier is dependent on the order of layer application.

```text
ChainID(A) = DiffID(A)
ChainID(A|B) = Digest(ChainID(A) + " " + DiffID(B))
ChainID(A|B|C) = Digest(ChainID(A|B) + " " + DiffID(C))
```

--------------------------------

### Count Merged PRs for Release Email

Source: https://github.com/opencontainers/image-spec/blob/main/RELEASES.md

Counts the number of merged pull requests between a prior tag and the current version bump commit. This is used to inform the release email.

```bash
git log --pretty=oneline --no-merges --decorate $priorTag..$versionBumpCommit  | grep \(pr\/ | wc -l
```