feat(extensions): add github release downloader

This specifically adds a downloader for github releases it uses either the

SHUTTLE_EXTENSIONS_GITHUB_ACCESS_TOKEN or GITHUB_ACCESS_TOKEN for access to the releases

The downloader expects a full url from the registry as seen in a previous pr

Signed-off-by: Kasper J. Hermansen <[email protected]>

internal/extensions/downloader.go

@@ -0,0 +1,68 @@
+package extensions
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"time"
+)
+
+type Downloader interface {
+	Download(ctx context.Context, dest string) error
+}
+
+func NewDownloader(downloadLink *registryExtensionDownloadLink) (Downloader, error) {
+	switch downloadLink.Provider {
+	case "github-release":
+		return newGitHubReleaseDownloader(downloadLink), nil
+	default:
+		return nil, fmt.Errorf("invalid provider type: %s", downloadLink.Provider)
+	}
+}
+
+type gitHubReleaseDownloader struct {
+	link *registryExtensionDownloadLink
+}
+
+func newGitHubReleaseDownloader(downloadLink *registryExtensionDownloadLink) Downloader {
+	return &gitHubReleaseDownloader{
+		link: downloadLink,
+	}
+}
+
+func (d *gitHubReleaseDownloader) Download(ctx context.Context, dest string) error {
+	client := http.DefaultClient
+
+	client.Timeout = time.Second * 60
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, d.link.Url, nil)
+	if err != nil {
+		return err
+	}
+
+	if accessToken := os.Getenv("SHUTTLE_EXTENSIONS_GITHUB_ACCESS_TOKEN"); accessToken != "" {
+		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", accessToken))
+	} else if accessToken := os.Getenv("GITHUB_ACCESS_TOKEN"); accessToken != "" {
+		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", accessToken))
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	extensionBinary, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer extensionBinary.Close()
+
+	if _, err := io.Copy(extensionBinary, resp.Body); err != nil {
+		return err
+	}
+
+	return nil
+}

internal/extensions/extension.go

@@ -47,9 +47,16 @@ func (e *Extension) Ensure(ctx context.Context) error {
 		return fmt.Errorf("failed to find a valid extension matching your os and architecture")
 	}
 
-	//TODO: Initiate download
+	downloader, err := NewDownloader(downloadLink)
+	if err != nil {
+		return err
+	}
+
+	if err := downloader.Download(ctx, binaryPath); err != nil {
+		return err
+	}
 
-	panic("not implemented yet")
+	return nil
 }
 
 func (e *Extension) getExtensionBinaryName() string {

internal/extensions/registry_index.go

@@ -59,6 +59,7 @@ type registryExtensionDownloadLink struct {
 	Os           string `json:"os"`
 	Url          string `json:"url"`
 	Checksum     string `json:"checksum"`
+	Provider     string `json:"provider"`
 }
 
 type registryExtension struct {