Add cnb.kontain.me, refactor and share a lot

pkg/internal.go

@@ -0,0 +1,140 @@
+package pkg
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os/exec"
+	"strings"
+
+	"cloud.google.com/go/storage"
+	"github.com/google/go-containerregistry/pkg/v1"
+	"google.golang.org/api/googleapi"
+)
+
+const bucket = "kontainme"
+
+func Run(stdout io.Writer, command string) error {
+	cmd := exec.Command("/bin/sh", "-c", command)
+	cmd.Stdout = stdout
+	cmd.Stderr = stdout
+	return cmd.Run()
+}
+
+func ServeBlob(w http.ResponseWriter, r *http.Request) {
+	// Extract requested blob digest and redirect to serve it from GCS.
+	// If it doesn't exist, this will return 404.
+	parts := strings.Split(r.URL.Path, "/")
+	digest := parts[len(parts)-1]
+	url := fmt.Sprintf("https://storage.googleapis.com/%s/blobs/%s", bucket, digest)
+	http.Redirect(w, r, url, http.StatusSeeOther)
+}
+
+func writeBlob(h v1.Hash, rc io.ReadCloser) error {
+	ctx := context.Background() // TODO
+	client, err := storage.NewClient(ctx)
+	if err != nil {
+		return fmt.Errorf("NewClient: %v", err)
+	}
+	// The DoesNotExist precondition can be hit when writing or flushing
+	// data, which can happen any of three places. Anywhere it happens,
+	// just ignore the error since that means the blob already exists.
+	w := client.Bucket(bucket).Object(fmt.Sprintf("blobs/%s", h)).
+		If(storage.Conditions{DoesNotExist: true}).
+		NewWriter(ctx)
+	if _, err := io.Copy(w, rc); err != nil {
+		if herr, ok := err.(*googleapi.Error); ok && herr.Code == http.StatusPreconditionFailed {
+			return nil
+		}
+		return fmt.Errorf("Copy: %v", err)
+	}
+	if err := rc.Close(); err != nil {
+		if herr, ok := err.(*googleapi.Error); ok && herr.Code == http.StatusPreconditionFailed {
+			return nil
+		}
+		return fmt.Errorf("rc.Close: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		if herr, ok := err.(*googleapi.Error); ok && herr.Code == http.StatusPreconditionFailed {
+			return nil
+		}
+		return fmt.Errorf("w.Close: %v", err)
+	}
+	return nil
+}
+
+// ServeManifest writes config and layer blobs for the image, then serves the
+// manifest contents pointing to those blobs.
+func ServeManifest(w http.ResponseWriter, img v1.Image) {
+	// Write config blob for later serving.
+	ch, err := img.ConfigName()
+	if err != nil {
+		log.Printf("ERROR (serveManifest ConfigName): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	cb, err := img.RawConfigFile()
+	if err != nil {
+		log.Printf("ERROR (serveManifest RawConfigFile): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	log.Printf("writing config blob %q", ch)
+	if err := writeBlob(ch, ioutil.NopCloser(bytes.NewReader(cb))); err != nil {
+		log.Printf("ERROR (serveManifest writeBlob): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Write layer blobs for later serving.
+	layers, err := img.Layers()
+	if err != nil {
+		log.Printf("ERROR (serveManifest Layers): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	for _, l := range layers {
+		rc, err := l.Compressed()
+		if err != nil {
+			log.Printf("ERROR (serveManifest l.Compressed): %s", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		lh, err := l.Digest()
+		if err != nil {
+			log.Printf("ERROR (serveManifest l.Digest): %s", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		log.Printf("writing layer blob %q", lh)
+		if err := writeBlob(lh, rc); err != nil {
+			log.Printf("ERROR (serveManifest writeBlob): %s", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+
+	// Serve the manifest.
+	b, err := img.RawManifest()
+	if err != nil {
+		log.Printf("ERROR (serveManifest RawManifest): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	mt, err := img.MediaType()
+	if err != nil {
+		log.Printf("ERROR (serveManifest MediaType): %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", string(mt))
+	if _, err := io.Copy(w, bytes.NewReader(b)); err != nil {
+		log.Printf("ERROR (serveManifest Copy): %s", err)
+		return
+	}
+	fmt.Printf("Served manifest: %s", string(b))
+}