feat(api): stream a track's stems as one zip

api/server.go

@@ -593,6 +593,7 @@ func NewApiServer(config config.Config) *ApiServer {
 		g.Post("/tracks/:trackId/reposts", app.requireAuthMiddleware, app.requireWriteScope, app.postV1TrackRepost)
 		g.Delete("/tracks/:trackId/reposts", app.requireAuthMiddleware, app.requireWriteScope, app.deleteV1TrackRepost)
 		g.Get("/tracks/:trackId/stems", app.v1TrackStems)
+		g.Get("/tracks/:trackId/stems/download", app.v1TrackStemsDownload)
 		g.Get("/tracks/:trackId/favorites", app.v1TrackFavorites)
 		g.Post("/tracks/:trackId/favorites", app.requireAuthMiddleware, app.requireWriteScope, app.postV1TrackFavorite)
 		g.Delete("/tracks/:trackId/favorites", app.requireAuthMiddleware, app.requireWriteScope, app.deleteV1TrackFavorite)

api/swagger/swagger-v1.yaml

@@ -4381,6 +4381,66 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/stems_response"
+  /tracks/{track_id}/stems/download:
+    get:
+      tags:
+        - tracks
+      summary: Download a track's stems as one zip
+      description:
+        Streams every stem the requester may download, and optionally the
+        parent track, as a single uncompressed zip with a known
+        Content-Length. Files that can't be downloaded are left out.
+      operationId: Download Track Stems
+      security:
+        - {}
+        - OAuth2:
+            - read
+      parameters:
+        - name: track_id
+          in: path
+          description: A Track ID
+          required: true
+          schema:
+            type: string
+        - name: include_parent
+          in: query
+          description: Optional - also include the parent track's file
+          schema:
+            type: boolean
+            default: false
+        - name: user_id
+          in: query
+          description: The user ID of the user making the request
+          schema:
+            type: string
+        - name: user_signature
+          in: query
+          description:
+            Optional - signature from the requesting user's wallet. Needed
+            for gated stems and for an artist downloading their own files.
+          schema:
+            type: string
+        - name: user_data
+          in: query
+          description:
+            Optional - data which was used to generate the optional signature
+            argument.
+          schema:
+            type: string
+      responses:
+        "200":
+          description: Success
+          content:
+            application/zip: {}
+        "403":
+          description: Not allowed to download any of the stems
+          content: {}
+        "404":
+          description: Track not found, or no downloadable stems
+          content: {}
+        "429":
+          description: Too many downloads in progress
+          content: {}
   /tracks/{track_id}/shares:
     post:
       tags:

api/v1_track_inspect.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"time"
 
 	"api.audius.co/api/dbv1"
 	"api.audius.co/rendezvous"
@@ -22,27 +23,28 @@ type inspectResponse struct {
 }
 
 func inspectTrack(track dbv1.Track, original bool) (*inspectResponse, error) {
-	var cid string
 	if original {
-		cid = track.OrigFileCid.String
-	} else {
-		cid = track.TrackCid.String
+		return inspectCid(track.OrigFileCid.String)
 	}
+	return inspectCid(track.TrackCid.String)
+}
+
+var inspectClient = &http.Client{Timeout: 10 * time.Second}
 
+func inspectCid(cid string) (*inspectResponse, error) {
 	hosts := rendezvous.GlobalHasher.Rank(cid)
 
 	var info blobInspect
 	var lastErr error
 
 	for _, host := range hosts {
-		client := &http.Client{}
 		req, err := http.NewRequest("GET", fmt.Sprintf("%s/internal/blobs/info/%s", host, cid), nil)
 		if err != nil {
 			lastErr = err
 			continue
 		}
 
-		resp, err := client.Do(req)
+		resp, err := inspectClient.Do(req)
 		if err != nil {
 			lastErr = err
 			continue