merge(quinistry): Integrate at //fun/quinistry r/260

This is too historically interesting for me to lose it.

8 files changed, 417 insertions, 0 deletions

diff --git a/fun/quinistry/.gitignore b/fun/quinistry/.gitignore
new file mode 100644
index 0000000000..622119552e
--- /dev/null
+++ b/fun/quinistry/.gitignore
@@ -0,0 +1,2 @@
+.idea/
+quinistry
\ No newline at end of file
diff --git a/fun/quinistry/README.md b/fun/quinistry/README.md
new file mode 100644
index 0000000000..de197a219e
--- /dev/null
+++ b/fun/quinistry/README.md
@@ -0,0 +1,63 @@
+Quinistry
+=========
+
+*A simple Docker registry quine.*
+
+## What?
+
+This is an example project for a from-scratch implementation of an HTTP server compatible with the [Docker Registry V2][]
+protocol.
+
+It serves a single image called `quinistry:latest` which is a Docker image that runs quinistry itself, therefore it is a
+sort of Docker registry [quine][].
+
+The official documentation does not contain enough information to actually implement this protocol (which I assume is
+intentional), but a bit of trial&error lead there anyways. I've added comments to parts of the code to clear up things
+that may be helpful to other developers in the future.
+
+## Example
+
+```
+# Run quinistry:
+vincent@urdhva ~/go/src/github.com/tazjin/quinistry (git)-[master] % ./quinistry
+2017/03/16 14:11:56 Starting quinistry
+
+# Pull the quinistry image from itself:
+vincent@urdhva ~ % docker pull localhost:8080/quinistry
+Using default tag: latest
+latest: Pulling from quinistry
+7bf1a8b18466: Already exists
+Digest: sha256:d5cd4490901ef04b4e28e4ccc03a1d25fe3461200cf4d7166aab86fcd495e22e
+Status: Downloaded newer image for localhost:8080/quinistry:latest
+
+# Quinistry will log:
+2017/03/16 14:14:03 Acknowleding V2 API: GET /v2/
+2017/03/16 14:14:03 Serving manifest: GET /v2/quinistry/manifests/latest
+2017/03/16 14:14:03 Serving config: GET /v2/quinistry/blobs/sha256:fbb165c48849de16017aa398aa9bb08fd1c00eaa7c150b6c2af37312913db279
+
+# Run the downloaded image:
+vincent@urdhva ~ % docker run -p 8090:8080 localhost:8080/quinistry
+2017/03/16 13:15:18 Starting quinistry
+
+# And download it again from itself:
+vincent@urdhva ~ % docker pull localhost:8090/quinistry
+Using default tag: latest
+latest: Pulling from quinistry
+7bf1a8b18466: Already exists
+Digest: sha256:11141d95ddce0bac9ffa32ab1e8bc94748ed923e87762c68858dc41d11a46d3f
+Status: Downloaded newer image for localhost:8090/quinistry:latest
+```
+
+## Building
+
+Quinistry creates a Docker image that only contains a statically linked `main` binary. As this package makes use of
+`net/http`, Go will (by default) link against `libc` for DNS resolution and create a dynamic binary instead.
+
+To disable this, `build` the project with `-tags netgo`:
+
+```
+go build -tags netgo
+```
+
+[Docker Registry V2]: https://docs.docker.com/registry/spec/api/
+[quine]: https://en.wikipedia.org/wiki/Quine_(computing)
\ No newline at end of file
diff --git a/fun/quinistry/const.go b/fun/quinistry/const.go
new file mode 100644
index 0000000000..173fa9efc3
--- /dev/null
+++ b/fun/quinistry/const.go
@@ -0,0 +1,12 @@
+package main
+
+// HTTP content types
+
+const ImageConfigMediaType string = "application/vnd.docker.container.image.v1+json"
+const ManifestMediaType string = "application/vnd.docker.distribution.manifest.v2+json"
+const LayerMediaType string = "application/vnd.docker.image.rootfs.diff.tar.gzip"
+
+// HTTP header names
+
+const ContentType string = "Content-Type"
+const DigestHeader string = "Docker-Content-Digest"
diff --git a/fun/quinistry/image.go b/fun/quinistry/image.go
new file mode 100644
index 0000000000..3daeac34d6
--- /dev/null
+++ b/fun/quinistry/image.go
@@ -0,0 +1,150 @@
+// The code in this file creates a Docker image layer containing the binary of the
+// application itself.
+
+package main
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"time"
+)
+
+// This function creates a Docker-image digest (i.e. SHA256 hash with
+// algorithm-specification prefix)
+func Digest(b []byte) string {
+	hash := sha256.New()
+	hash.Write(b)
+
+	return fmt.Sprintf("sha256:%x", hash.Sum(nil))
+}
+
+func GetImageOfCurrentExecutable() Image {
+	binary := getCurrentBinary()
+	tarArchive := createTarArchive(&map[string][]byte{
+		"/main": binary,
+	})
+
+	configJson, configElem := createConfig([]string{Digest(tarArchive)})
+	compressed := gzipArchive("Quinistry image", tarArchive)
+	manifest := createManifest(&configElem, &compressed)
+	manifestJson, _ := json.Marshal(manifest)
+
+	return Image{
+		Layer:          compressed,
+		LayerDigest:    Digest(compressed),
+		Manifest:       manifestJson,
+		ManifestDigest: Digest(manifestJson),
+		Config:         configJson,
+		ConfigDigest:   Digest(configJson),
+	}
+
+}
+
+func getCurrentBinary() []byte {
+	path, _ := os.Executable()
+	file, _ := ioutil.ReadFile(path)
+	return file
+}
+
+func createTarArchive(files *map[string][]byte) []byte {
+	buf := new(bytes.Buffer)
+	w := tar.NewWriter(buf)
+
+	for name, file := range *files {
+		hdr := &tar.Header{
+			Name: name,
+			// Everything is executable \o/
+			Mode: 0755,
+			Size: int64(len(file)),
+		}
+		w.WriteHeader(hdr)
+		w.Write(file)
+	}
+
+	if err := w.Close(); err != nil {
+		log.Fatalln(err)
+		os.Exit(1)
+	}
+
+	return buf.Bytes()
+}
+
+func gzipArchive(name string, archive []byte) []byte {
+	buf := new(bytes.Buffer)
+	w := gzip.NewWriter(buf)
+	w.Name = name
+	w.Write(archive)
+
+	if err := w.Close(); err != nil {
+		log.Fatalln(err)
+		os.Exit(1)
+	}
+
+	return buf.Bytes()
+}
+
+func createConfig(layerDigests []string) (configJson []byte, elem Element) {
+	now := time.Now()
+
+	imageConfig := &ImageConfig{
+		Cmd: []string{"/main"},
+		Env: []string{"PATH=/"},
+	}
+
+	rootFs := RootFs{
+		DiffIds: layerDigests,
+		Type:    "layers",
+	}
+
+	history := []History{
+		{
+			Created:   now,
+			CreatedBy: "Quinistry magic",
+		},
+	}
+
+	config := Config{
+		Created:      now,
+		Author:       "tazjin",
+		Architecture: "amd64",
+		Os:           "linux",
+		Config:       imageConfig,
+		RootFs:       rootFs,
+		History:      history,
+	}
+
+	configJson, _ = json.Marshal(config)
+
+	elem = Element{
+		MediaType: ImageConfigMediaType,
+		Size:      len(configJson),
+		Digest:    Digest(configJson),
+	}
+
+	return
+}
+
+func createManifest(config *Element, layer *[]byte) Manifest {
+	layers := []Element{
+		{
+			MediaType: LayerMediaType,
+			Size:      len(*layer),
+			// Layers must contain the digest of the *gzipped* layer.
+			Digest: Digest(*layer),
+		},
+	}
+
+	return Manifest{
+		SchemaVersion: 2,
+		MediaType:     ManifestMediaType,
+		Config:        *config,
+		Layers:        layers,
+	}
+}
diff --git a/fun/quinistry/k8s/child.yaml b/fun/quinistry/k8s/child.yaml
new file mode 100644
index 0000000000..aa2e318262
--- /dev/null
+++ b/fun/quinistry/k8s/child.yaml
@@ -0,0 +1,27 @@
+# This is a child quinistry, running via an image served off the parent.
+---
+apiVersion: extensions/v1beta1
+kind: DaemonSet
+metadata:
+  name: quinistry-gen2
+  labels:
+    k8s-app: quinistry
+    quinistry/role: child
+    quinistry/generation: '2'
+spec:
+  template:
+    metadata:
+      labels:
+        k8s-app: quinistry
+        quinistry/role: child
+        quinistry/generation: '2'
+    spec:
+      containers:
+        - name: quinistry
+          # Bootstrap via Docker Hub (or any other registry)
+          image: localhost:5000/quinistry
+          ports:
+            - name: registry
+              containerPort: 8080
+              # Incremented hostPort, 
+              hostPort: 5001
diff --git a/fun/quinistry/k8s/parent.yaml b/fun/quinistry/k8s/parent.yaml
new file mode 100644
index 0000000000..0db2fe300e
--- /dev/null
+++ b/fun/quinistry/k8s/parent.yaml
@@ -0,0 +1,27 @@
+# This is a bootstrapped Quinistry DaemonSet. The initial image
+# comes from Docker Hub
+---
+apiVersion: extensions/v1beta1
+kind: DaemonSet
+metadata:
+  name: quinistry
+  labels:
+    k8s-app: quinistry
+    quinistry/role: parent
+    quinistry/generation: '1'
+spec:
+  template:
+    metadata:
+      labels:
+        k8s-app: quinistry
+        quinistry/role: parent
+        quinistry/generation: '1'
+    spec:
+      containers:
+        - name: quinistry
+          # Bootstrap via Docker Hub (or any other registry)
+          image: tazjin/quinistry
+          ports:
+            - name: registry
+              containerPort: 8080
+              hostPort: 5000
diff --git a/fun/quinistry/main.go b/fun/quinistry/main.go
new file mode 100644
index 0000000000..50b47418d1
--- /dev/null
+++ b/fun/quinistry/main.go
@@ -0,0 +1,57 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func main() {
+	log.Println("Starting quinistry")
+
+	image := GetImageOfCurrentExecutable()
+
+	layerUri := fmt.Sprintf("/v2/quinistry/blobs/%s", image.LayerDigest)
+	configUri := fmt.Sprintf("/v2/quinistry/blobs/%s", image.ConfigDigest)
+
+	log.Fatal(http.ListenAndServe(":8080", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Acknowledge that we speak V2
+		if r.RequestURI == "/v2/" {
+			logRequest("Acknowleding V2 API", r)
+			fmt.Fprintln(w)
+			return
+		}
+
+		// Serve manifest
+		if r.RequestURI == "/v2/quinistry/manifests/latest" {
+			logRequest("Serving manifest", r)
+			w.Header().Set(ContentType, ManifestMediaType)
+			w.Header().Add(DigestHeader, image.ManifestDigest)
+			w.Write(image.Manifest)
+			return
+		}
+
+		// Serve actual image layer
+		if r.RequestURI == layerUri {
+			logRequest("Serving image layer blob", r)
+			w.Header().Add(DigestHeader, image.LayerDigest)
+			w.Write(image.Layer)
+			return
+		}
+
+		// Serve image config
+		if r.RequestURI == configUri {
+			logRequest("Serving config", r)
+			w.Header().Set("Content-Type", ImageConfigMediaType)
+			w.Header().Set(DigestHeader, image.ConfigDigest)
+			w.Write(image.Config)
+			return
+		}
+
+		log.Printf("Unhandled request: %v\n", *r)
+	})))
+}
+
+func logRequest(msg string, r *http.Request) {
+	log.Printf("%s: %s %s\n", msg, r.Method, r.RequestURI)
+}
diff --git a/fun/quinistry/types.go b/fun/quinistry/types.go
new file mode 100644
index 0000000000..498cbac2f2
--- /dev/null
+++ b/fun/quinistry/types.go
@@ -0,0 +1,79 @@
+package main
+
+import "time"
+
+// This type represents the rootfs-key of the Docker image config.
+// It specifies the digest (i.e. usually SHA256 hash) of the tar'ed, but NOT
+// compressed image layers.
+type RootFs struct {
+	// The digests of the non-compressed FS layers.
+	DiffIds []string `json:"diff_ids"`
+
+	// Type should always be set to "layers"
+	Type string `json:"type"`
+}
+
+// This type represents an entry in the Docker image config's history key.
+// Every history element "belongs" to a filesystem layer.
+type History struct {
+	Created   time.Time `json:"created"`
+	CreatedBy string    `json:"created_by"`
+}
+
+// This type represents runtime-configuration for the Docker image.
+// A lot of possible keys are omitted here, see:
+// https://github.com/docker/docker/blob/master/image/spec/v1.2.md#image-json-description
+type ImageConfig struct {
+	Cmd []string
+	Env []string
+}
+
+// This type represents the Docker image configuration
+type Config struct {
+	Created time.Time `json:"created"`
+	Author  string    `json:"author"`
+
+	// Architecture should be "amd64"
+	Architecture string `json:"architecture"`
+
+	// OS should be "linux"
+	Os string `json:"os"`
+
+	// Configuration can be set to 'nil', in which case all options have to be
+	// supplied at container launch time.
+	Config *ImageConfig `json:"config"`
+
+	// Filesystem layers and history elements have to be in the same order.
+	RootFs  RootFs    `json:"rootfs"`
+	History []History `json:"history"`
+}
+
+// This type represents any manifest
+type Element struct {
+	MediaType string `json:"mediaType"`
+	Size      int    `json:"size"`
+	Digest    string `json:"digest"`
+}
+
+// This type represents a Docker image manifest as used by the registry
+// protocol V2.
+type Manifest struct {
+	SchemaVersion int       `json:"schemaVersion"` // Must be 2
+	MediaType     string    `json:"mediaType"`     // Use ManifestMediaType const
+	Config        Element   `json:"config"`
+	Layers        []Element `json:"layers"`
+}
+
+// A really "dumb" representation of an image, with its data blob and related
+// metadata.
+// Note: This is not a registry API type.
+type Image struct {
+	Layer       []byte
+	LayerDigest string
+
+	Manifest       []byte
+	ManifestDigest string
+
+	Config       []byte
+	ConfigDigest string
+}