fix: fix context plumbing in gateway handlers (#8871)

This ensures that child contexts are passed around between
the handlers so that traces show the call hierarchy correctly.

Author: guseggert

core/corehttp/gateway_handler.go

@@ -443,16 +443,16 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 	switch responseFormat {
 	case "": // The implicit response format is UnixFS
 		logger.Debugw("serving unixfs", "path", contentPath)
-		i.serveUnixFs(w, r, resolvedPath, contentPath, begin, logger)
+		i.serveUnixFS(r.Context(), w, r, resolvedPath, contentPath, begin, logger)
 		return
 	case "application/vnd.ipld.raw":
 		logger.Debugw("serving raw block", "path", contentPath)
-		i.serveRawBlock(w, r, resolvedPath, contentPath, begin)
+		i.serveRawBlock(r.Context(), w, r, resolvedPath, contentPath, begin)
 		return
 	case "application/vnd.ipld.car":
 		logger.Debugw("serving car stream", "path", contentPath)
 		carVersion := formatParams["version"]
-		i.serveCar(w, r, resolvedPath, contentPath, carVersion, begin)
+		i.serveCAR(r.Context(), w, r, resolvedPath, contentPath, carVersion, begin)
 		return
 	default: // catch-all for unsuported application/vnd.*
 		err := fmt.Errorf("unsupported format %q", responseFormat)

core/corehttp/gateway_handler_block.go

@@ -2,6 +2,7 @@ package corehttp
 
 import (
 	"bytes"
+	"context"
 	"io/ioutil"
 	"net/http"
 	"time"
@@ -13,8 +14,8 @@ import (
 )
 
 // serveRawBlock returns bytes behind a raw block
-func (i *gatewayHandler) serveRawBlock(w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time) {
-	ctx, span := tracing.Span(r.Context(), "Gateway", "ServeRawBlock", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+func (i *gatewayHandler) serveRawBlock(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time) {
+	ctx, span := tracing.Span(ctx, "Gateway", "ServeRawBlock", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 	blockCid := resolvedPath.Cid()
 	blockReader, err := i.api.Block().Get(ctx, resolvedPath)

core/corehttp/gateway_handler_car.go

@@ -17,9 +17,9 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-// serveCar returns a CAR stream for specific DAG+selector
-func (i *gatewayHandler) serveCar(w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, carVersion string, begin time.Time) {
-	ctx, span := tracing.Span(r.Context(), "Gateway", "ServeCar", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+// serveCAR returns a CAR stream for specific DAG+selector
+func (i *gatewayHandler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, carVersion string, begin time.Time) {
+	ctx, span := tracing.Span(ctx, "Gateway", "ServeCAR", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()

core/corehttp/gateway_handler_unixfs.go

@@ -1,6 +1,7 @@
 package corehttp
 
 import (
+	"context"
 	"fmt"
 	"html"
 	"net/http"
@@ -14,8 +15,8 @@ import (
 	"go.uber.org/zap"
 )
 
-func (i *gatewayHandler) serveUnixFs(w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time, logger *zap.SugaredLogger) {
-	ctx, span := tracing.Span(r.Context(), "Gateway", "ServeUnixFs", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+func (i *gatewayHandler) serveUnixFS(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time, logger *zap.SugaredLogger) {
+	ctx, span := tracing.Span(ctx, "Gateway", "ServeUnixFS", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 	// Handling UnixFS
 	dr, err := i.api.Unixfs().Get(ctx, resolvedPath)
@@ -28,16 +29,16 @@ func (i *gatewayHandler) serveUnixFs(w http.ResponseWriter, r *http.Request, res
 	// Handling Unixfs file
 	if f, ok := dr.(files.File); ok {
 		logger.Debugw("serving unixfs file", "path", contentPath)
-		i.serveFile(w, r, resolvedPath, contentPath, f, begin)
+		i.serveFile(ctx, w, r, resolvedPath, contentPath, f, begin)
 		return
 	}
 
 	// Handling Unixfs directory
 	dir, ok := dr.(files.Directory)
 	if !ok {
-		internalWebError(w, fmt.Errorf("unsupported UnixFs type"))
+		internalWebError(w, fmt.Errorf("unsupported UnixFS type"))
 		return
 	}
 	logger.Debugw("serving unixfs directory", "path", contentPath)
-	i.serveDirectory(w, r, resolvedPath, contentPath, dir, begin, logger)
+	i.serveDirectory(ctx, w, r, resolvedPath, contentPath, dir, begin, logger)
 }

core/corehttp/gateway_handler_unixfs_dir.go

@@ -1,6 +1,7 @@
 package corehttp
 
 import (
+	"context"
 	"net/http"
 	"net/url"
 	gopath "path"
@@ -23,8 +24,8 @@ import (
 // serveDirectory returns the best representation of UnixFS directory
 //
 // It will return index.html if present, or generate directory listing otherwise.
-func (i *gatewayHandler) serveDirectory(w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, dir files.Directory, begin time.Time, logger *zap.SugaredLogger) {
-	ctx, span := tracing.Span(r.Context(), "Gateway", "ServeDirectory", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+func (i *gatewayHandler) serveDirectory(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, dir files.Directory, begin time.Time, logger *zap.SugaredLogger) {
+	ctx, span := tracing.Span(ctx, "Gateway", "ServeDirectory", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 
 	// HostnameOption might have constructed an IPNS/IPFS path using the Host header.
@@ -69,7 +70,7 @@ func (i *gatewayHandler) serveDirectory(w http.ResponseWriter, r *http.Request,
 
 		logger.Debugw("serving index.html file", "path", idxPath)
 		// write to request
-		i.serveFile(w, r, resolvedPath, idxPath, f, begin)
+		i.serveFile(ctx, w, r, resolvedPath, idxPath, f, begin)
 		return
 	case resolver.ErrNoLink:
 		logger.Debugw("no index.html; noop", "path", idxPath)

core/corehttp/gateway_handler_unixfs_file.go

@@ -1,6 +1,7 @@
 package corehttp
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"mime"
@@ -19,8 +20,8 @@ import (
 
 // serveFile returns data behind a file along with HTTP headers based on
 // the file itself, its CID and the contentPath used for accessing it.
-func (i *gatewayHandler) serveFile(w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, file files.File, begin time.Time) {
-	_, span := tracing.Span(r.Context(), "Gateway", "ServeFile", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+func (i *gatewayHandler) serveFile(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, file files.File, begin time.Time) {
+	_, span := tracing.Span(ctx, "Gateway", "ServeFile", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 
 	// Set Cache-Control and read optional Last-Modified time