refactor: Split up code for readability and add docs

1 files changed, 11 insertions, 141 deletions

diff --git a/main.go b/main.go
index ad1470e9eb..50b47418d1 100644
--- a/main.go
+++ b/main.go
@@ -1,92 +1,18 @@
 package main
 
 import (
-	"archive/tar"
-	"bytes"
-	"compress/gzip"
-	"crypto/sha256"
-	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"net/http"
-	"os"
-	"time"
 )
 
-const ImageContentType string = "application/vnd.docker.container.image.v1+json"
-const ManifestContentType string = "application/vnd.docker.distribution.manifest.v2+json"
-const LayerContentType string = "application/vnd.docker.image.rootfs.diff.tar.gzip"
-const DigestHeader string = "Docker-Content-Digest"
-
-type Element struct {
-	MediaType string `json:"mediaType"`
-	Size      int    `json:"size"`
-	Digest    string `json:"digest"`
-}
-
-type Manifest struct {
-	SchemaVersion int       `json:"schemaVersion"`
-	MediaType     string    `json:"mediaType"`
-	Config        Element   `json:"config"`
-	Layers        []Element `json:"layers"`
-}
-
-// A really "dumb" representation of an image, with a data blob (tar.gz image) and its hash as the type expected
-// in the manifest.
-type Image struct {
-	Data       []byte
-	TarDigest  string
-	GzipDigest string
-}
-
 func main() {
 	log.Println("Starting quinistry")
 
-	img := getImage()
-	now := time.Now()
-
-	config := Config{
-		Created:      now,
-		Author:       "tazjin",
-		Architecture: "amd64",
-		Os:           "linux",
-		Config: &ImageConfig{
-			Cmd: []string{"main"},
-			Env: []string{"PATH=/"},
-		},
-		RootFs: RootFs{
-			DiffIds: []string{
-				img.TarDigest,
-			},
-			Type: "layers",
-		},
-		History: []History{
-			{
-				Created:   now,
-				CreatedBy: "quinistry magic",
-			},
-		},
-	}
-
-	configJson, _ := json.Marshal(config)
+	image := GetImageOfCurrentExecutable()
 
-	manifest := Manifest{
-		SchemaVersion: 2,
-		MediaType:     ManifestContentType,
-		Config: Element{
-			MediaType: ImageContentType,
-			Size:      len(configJson),
-			Digest:    digest(configJson),
-		},
-		Layers: []Element{
-			{
-				MediaType: LayerContentType,
-				Size:      len(img.Data),
-				Digest:    img.GzipDigest,
-			},
-		},
-	}
+	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
@@ -99,29 +25,26 @@ func main() {
 		// Serve manifest
 		if r.RequestURI == "/v2/quinistry/manifests/latest" {
 			logRequest("Serving manifest", r)
-			w.Header().Add("Content-Type", ManifestContentType)
-			resp, _ := json.Marshal(manifest)
-			w.Header().Add(DigestHeader, digest(resp))
-			w.Write(resp)
+			w.Header().Set(ContentType, ManifestMediaType)
+			w.Header().Add(DigestHeader, image.ManifestDigest)
+			w.Write(image.Manifest)
 			return
 		}
 
 		// Serve actual image layer
-		layerUri := fmt.Sprintf("/v2/quinistry/blobs/%s", img.GzipDigest)
 		if r.RequestURI == layerUri {
 			logRequest("Serving image layer blob", r)
-			w.Header().Add(DigestHeader, img.GzipDigest)
-			w.Write(img.Data)
+			w.Header().Add(DigestHeader, image.LayerDigest)
+			w.Write(image.Layer)
 			return
 		}
 
 		// Serve image config
-		configUri := fmt.Sprintf("/v2/quinistry/blobs/%s", digest(configJson))
 		if r.RequestURI == configUri {
 			logRequest("Serving config", r)
-			w.Header().Set("Content-Type", ImageContentType)
-			w.Header().Set(DigestHeader, digest(configJson))
-			w.Write(configJson)
+			w.Header().Set("Content-Type", ImageConfigMediaType)
+			w.Header().Set(DigestHeader, image.ConfigDigest)
+			w.Write(image.Config)
 			return
 		}
 
@@ -132,56 +55,3 @@ func main() {
 func logRequest(msg string, r *http.Request) {
 	log.Printf("%s: %s %s\n", msg, r.Method, r.RequestURI)
 }
-
-func digest(b []byte) string {
-	hash := sha256.New()
-	hash.Write(b)
-
-	return fmt.Sprintf("sha256:%x", hash.Sum(nil))
-}
-
-// Creates an image of the currently running binary (spooky!)
-func getImage() *Image {
-	// Current binary, imagine this is some other output or whatever
-	path, _ := os.Executable()
-
-	// don't care about error! :O
-	file, _ := ioutil.ReadFile(path)
-
-	// First create tar archive
-	tarBuf := new(bytes.Buffer)
-	tarW := tar.NewWriter(tarBuf)
-	hdr := &tar.Header{
-		Name: "/main",
-		Mode: 0755,
-		Size: int64(len(file)),
-	}
-	tarW.WriteHeader(hdr)
-	tarW.Write(file)
-
-	if err := tarW.Close(); err != nil {
-		log.Fatalln(err)
-		os.Exit(1)
-	}
-
-	tarBytes := tarBuf.Bytes()
-
-	// Then GZIP it
-	zBuf := new(bytes.Buffer)
-	zw := gzip.NewWriter(zBuf)
-	zw.Name = "Docker registry fake test"
-
-	zw.Write(tarBytes)
-	if err := zw.Close(); err != nil {
-		log.Fatal(err)
-		os.Exit(1)
-	}
-
-	gzipData := zBuf.Bytes()
-
-	return &Image{
-		TarDigest:  digest(tarBytes),
-		GzipDigest: digest(gzipData),
-		Data:       gzipData,
-	}
-}