go/twitterchiver: port relatedfetcher to gocloud.dev

go/twitterchiver/default.nix

@@ -47,6 +47,9 @@
       depot.third_party.gopkgs."github.com".dghubble.oauth1
       depot.third_party.gopkgs."github.com".jackc.pgtype
       depot.third_party.gopkgs."github.com".jackc.pgx.v4.pgxpool
+      depot.third_party.gopkgs."gocloud.dev".blob
+      depot.third_party.gopkgs."gocloud.dev".blob.s3blob
+      depot.third_party.gopkgs."gocloud.dev".gcerrors
     ];
   };
 }

go/twitterchiver/related_fetcher/fetcher.go

@@ -24,6 +24,10 @@ import (
 	"github.com/jackc/pgtype"
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
+	"gocloud.dev/blob"
+	"gocloud.dev/gcerrors"
+
+	_ "gocloud.dev/blob/s3blob"
 )
 
 var (
@@ -32,7 +36,7 @@ var (
 	workerCount  = flag.Int("workers", 20, "Workers to spawn for fetching info from Twitter API")
 	workAtOnce   = flag.Int("work_at_once", 40, "Work to enqueue at once (i.e. we will only look for this much work to do).")
 
-	mediaFetchDestination = flag.String("media_fetch_destination", "/tmp", "Path to write fetched media to.")
+	mediaFetchDestination = flag.String("media_fetch_destination", "s3://public-lukegb-twitterchiver?endpoint=objdump.zxcvbnm.ninja&region=london", "gocloud.dev URL to write fetched media to.")
 	mediaTickInterval     = flag.Duration("media_tick_interval", 0, "Tick interval for media - takes priority over --tick_interval if non-zero.")
 	mediaWorkAtOnce       = flag.Int("media_work_at_once", 0, "Work to enqueue at once for media - takes priority over --work_at_once if non-zero.")
 
@@ -48,6 +52,7 @@ type WorkerConfig struct {
 	OAuthConfig  *oauth1.Config
 	WorkAtOnce   int
 	DatabasePool *pgxpool.Pool
+	Bucket       *blob.Bucket
 
 	WorkQueue chan func(context.Context)
 }
@@ -116,7 +121,7 @@ func mediaFetchOutputPath(u string) (string, error) {
 	}
 	path := strings.TrimLeft(p.Path, "/")
 
-	return filepath.Join(*mediaFetchDestination, p.Host, path), nil
+	return filepath.Join(p.Host, path), nil
 }
 
 type databaseQuerier interface {
@@ -211,24 +216,19 @@ func mediaFetchTick(ctx context.Context, cfg WorkerConfig) error {
 				}
 
 				// Fetch u -> out
-				if fi, err := os.Stat(out); err == nil {
+				if fi, err := cfg.Bucket.Attributes(ctx, out); err == nil {
 					// File already exists, does it have non-zero size?
-					if fi.Size() > 0 {
+					if fi.Size > 0 {
 						// It does!
 						log.Printf("[%v:%d:%v] %v already exists; skipping", cfg.Name, t.ID, u, out)
 						continue
 					}
 					log.Printf("[%v:%d:%v] %v already exists but has zero size; refetching", cfg.Name, t.ID, u, out)
-				} else if !os.IsNotExist(err) {
+				} else if gcerrors.Code(err) == gcerrors.NotFound {
 					log.Printf("[%v:%d:%v] checking output path %v: %v", cfg.Name, t.ID, u, out, err)
 					return
 				}
 
-				if err := os.MkdirAll(filepath.Dir(out), 0755); err != nil {
-					log.Printf("[%v:%d:%v] creating output path %v: %v", cfg.Name, t.ID, u, out, err)
-					return
-				}
-
 				if err := func() error {
 					resp, err := http.Get(u)
 					if err != nil {
@@ -246,21 +246,21 @@ func mediaFetchTick(ctx context.Context, cfg WorkerConfig) error {
 						return fmt.Errorf("HTTP status %d - %v", resp.StatusCode, resp.Status)
 					}
 
-					f, err := os.Create(out)
+					f, err := cfg.Bucket.NewWriter(ctx, out, nil)
 					if err != nil {
 						return err
 					}
-					defer f.Close()
 
 					written, err := io.Copy(f, resp.Body)
 					if err != nil {
 						// Try to delete the file we created to force a refetch next time.
-						_ = f.Truncate(0) // Ignore the error, though.
+						_ = f.Close()
+						_ = cfg.Bucket.Delete(ctx, out)
 						return fmt.Errorf("IO error: %w", err)
 					}
 					log.Printf("[%v:%d:%v] downloaded %d bytes.", cfg.Name, t.ID, u, written)
 
-					return nil
+					return f.Close()
 				}(); err != nil {
 					log.Printf("[%v:%d:%v] %v", cfg.Name, t.ID, u, err)
 					return