diff --git a/pkg/api/etag_middleware.go b/pkg/api/etag_middleware.go new file mode 100644 index 00000000000..32d54895782 --- /dev/null +++ b/pkg/api/etag_middleware.go @@ -0,0 +1,78 @@ +package api + +import ( + "crypto/md5" //nolint:gosec + "encoding/hex" + "io" + "io/fs" + "net/http" + "path" + "strings" +) + +// EtagMiddleware returns a new Etag middleware handler. +// It designs to work on embedded FS, where the content doesn't change. +// It calculates the Etag for each file on startup and serves it on each request. +func EtagMiddleware(root fs.FS, next http.Handler) http.Handler { + etags, err := scanFSEtags(root) + if err != nil { + panic(err) + } + return &etagHandler{ + root: root, + next: next, + etags: etags, + } +} + +type etagHandler struct { + root fs.FS + next http.Handler + etags map[string]string +} + +func (e *etagHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) { + upath := r.URL.Path + if !strings.HasPrefix(upath, "/") { + upath = "/" + upath + } + upath = path.Clean(upath) + if strings.HasSuffix(upath, "/") { + upath += "index.html" + } + etag, ok := e.etags[upath] + if ok { + w.Header().Set("Etag", "\""+etag+"\"") + } + e.next.ServeHTTP(w, r) +} + +func scanFSEtags(fSys fs.FS) (map[string]string, error) { + etags := make(map[string]string) + err := fs.WalkDir(fSys, ".", func(fpath string, d fs.DirEntry, err error) error { + if err != nil { + return err + } + if d.IsDir() { + return nil + } + + f, err := fSys.Open(fpath) + if err != nil { + return err + } + defer func() { _ = f.Close() }() + + h := md5.New() //nolint:gosec + if _, err := io.Copy(h, f); err != nil { + return err + } + hashValue := hex.EncodeToString(h.Sum(nil)) + etags["/"+fpath] = hashValue + return nil + }) + if err != nil { + return nil, err + } + return etags, nil +} diff --git a/pkg/api/ui_handler.go b/pkg/api/ui_handler.go index 899a7a18867..8db6a18aafd 100644 --- a/pkg/api/ui_handler.go +++ b/pkg/api/ui_handler.go @@ -9,7 +9,6 @@ import ( "strings" gomime "github.com/cubewise-code/go-mime" - "github.com/go-chi/chi/v5/middleware" "github.com/treeverse/lakefs/pkg/api/params" gwerrors "github.com/treeverse/lakefs/pkg/gateway/errors" "github.com/treeverse/lakefs/pkg/gateway/operations" @@ -34,8 +33,8 @@ func NewUIHandler(gatewayDomains []string, snippets []params.CodeSnippet) http.H panic(err) } fileSystem := http.FS(injectedContent) - nocacheContent := middleware.NoCache(http.StripPrefix("/", http.FileServer(fileSystem))) - return NewHandlerWithDefault(fileSystem, nocacheContent, gatewayDomains) + etagHandler := EtagMiddleware(injectedContent, http.StripPrefix("/", http.FileServer(fileSystem))) + return NewHandlerWithDefault(fileSystem, etagHandler, gatewayDomains) } func NewS3GatewayEndpointErrorHandler(gatewayDomains []string) http.Handler { @@ -45,7 +44,7 @@ func NewS3GatewayEndpointErrorHandler(gatewayDomains []string) http.Handler { return } - // For other requests, return generic not found error + // For other requests, return generic "not found" error w.WriteHeader(http.StatusNotFound) }) }