Print the response's body on demand for debugging purposes (#276)

* Implement debugging functionality when reading a response's body

* Remove the silliness :)

December 28 has passed already

* Don't use log.Print for writing to Stdout

* Add important note

* Update flake.lock

* Add fmt.Fprint to the list of unhandled errors

* End comment with a period

* Remove the comment completely

* Document a method as having its documentation pending

* Remove TODO line

* Activate printing the response body from envvars

- Adds `BATON_DEBUG_PRINT_RESPONSE_BODY`

* Remove `logBody` unexported function

.golangci.yml

@@ -36,6 +36,7 @@ linters-settings:
         arguments:
           - fmt.Printf
           - fmt.Println
+          - fmt.Fprint
           - fmt.Fprintf
           - fmt.Fprintln
           - os.Stderr.Sync

pkg/sync/syncer.go

@@ -33,9 +33,7 @@ const maxDepth = 8
 
 var dontFixCycles, _ = strconv.ParseBool(os.Getenv("BATON_DONT_FIX_CYCLES"))
 
-var (
-	ErrSyncNotComplete = fmt.Errorf("sync exited without finishing")
-)
+var ErrSyncNotComplete = fmt.Errorf("sync exited without finishing")
 
 type Syncer interface {
 	Sync(context.Context) error
@@ -973,8 +971,7 @@ func (s *syncer) SyncAssets(ctx context.Context) error {
 	return nil
 }
 
-// SyncGrantExpansion
-// TODO(morgabra) Docs.
+// SyncGrantExpansion documentation pending.
 func (s *syncer) SyncGrantExpansion(ctx context.Context) error {
 	l := ctxzap.Extract(ctx)
 	entitlementGraph := s.state.EntitlementGraph(ctx)

pkg/uhttp/body_print.go

@@ -0,0 +1,40 @@
+package uhttp
+
+// Implements a debugging facility for request responses. This changes
+// the behavior of `BaseHttpClient` with an unexported flag.
+//
+// IMPORTANT: This feature is intended for development and debugging purposes only.
+// Do not enable in production as it may expose sensitive information in logs.
+//
+// Usage:
+//   client := uhttp.NewBaseHttpClient(
+//     httpClient,
+//     uhttp.WithPrintBody(true), // Enable response body printing
+//   )
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+)
+
+type printReader struct {
+	reader io.Reader
+}
+
+func (pr *printReader) Read(p []byte) (int, error) {
+	n, err := pr.reader.Read(p)
+	if n > 0 {
+		_, merr := fmt.Fprint(os.Stdout, string(p[:n]))
+		if merr != nil {
+			return -1, errors.Join(err, merr)
+		}
+	}
+
+	return n, err
+}
+
+func wrapPrintBody(body io.Reader) io.Reader {
+	return &printReader{reader: body}
+}

pkg/uhttp/wrapper.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"os"
 	"syscall"
 	"time"
 
@@ -33,8 +34,6 @@ const (
 	authorizationHeader       = "Authorization"
 )
 
-const maxBodySize = 4096
-
 type WrapperResponse struct {
 	Header     http.Header
 	Body       []byte
@@ -140,8 +139,8 @@ func WithJSONResponse(response interface{}) DoOption {
 
 		if !IsJSONContentType(contentHeader) {
 			if len(resp.Body) != 0 {
-				// we want to see the body regardless
-				return fmt.Errorf("unexpected content type for JSON response: %s. status code: %d. body: «%s»", contentHeader, resp.StatusCode, logBody(resp.Body, maxBodySize))
+				// to print the response, set the envvar BATON_DEBUG_PRINT_RESPONSE_BODY as non-empty, instead
+				return fmt.Errorf("unexpected content type for JSON response: %s. status code: %d", contentHeader, resp.StatusCode)
 			}
 			return fmt.Errorf("unexpected content type for JSON response: %s. status code: %d", contentHeader, resp.StatusCode)
 		}
@@ -150,7 +149,8 @@ func WithJSONResponse(response interface{}) DoOption {
 		}
 		err := json.Unmarshal(resp.Body, response)
 		if err != nil {
-			return fmt.Errorf("failed to unmarshal json response: %w. status code: %d. body %v", err, resp.StatusCode, logBody(resp.Body, maxBodySize))
+			// to print the response, set the envvar BATON_DEBUG_PRINT_RESPONSE_BODY as non-empty, instead
+			return fmt.Errorf("failed to unmarshal json response: %w. status code: %d", err, resp.StatusCode)
 		}
 		return nil
 	}
@@ -164,19 +164,13 @@ func WithAlwaysJSONResponse(response interface{}) DoOption {
 		}
 		err := json.Unmarshal(resp.Body, response)
 		if err != nil {
-			return fmt.Errorf("failed to unmarshal json response: %w. status code: %d. body %v", err, resp.StatusCode, logBody(resp.Body, maxBodySize))
+			// to print the response, set the envvar BATON_DEBUG_PRINT_RESPONSE_BODY as non-empty, instead
+			return fmt.Errorf("failed to unmarshal json response: %w. status code: %d", err, resp.StatusCode)
 		}
 		return nil
 	}
 }
 
-func logBody(body []byte, size int) string {
-	if len(body) > size {
-		return string(body[:size]) + " ..."
-	}
-	return string(body)
-}
-
 type ErrorResponse interface {
 	Message() string
 }
@@ -190,12 +184,14 @@ func WithErrorResponse(resource ErrorResponse) DoOption {
 		contentHeader := resp.Header.Get(ContentType)
 
 		if !IsJSONContentType(contentHeader) {
-			return fmt.Errorf("unexpected content type for JSON error response: %s. status code: %d. body: «%s»", contentHeader, resp.StatusCode, logBody(resp.Body, maxBodySize))
+			// to print the response, set the envvar BATON_DEBUG_PRINT_RESPONSE_BODY as non-empty, instead
+			return fmt.Errorf("unexpected content type for JSON error response: %s. status code: %d", contentHeader, resp.StatusCode)
 		}
 
 		// Decode the JSON response body into the ErrorResponse
 		if err := json.Unmarshal(resp.Body, &resource); err != nil {
-			return fmt.Errorf("failed to unmarshal JSON error response: %w. status code: %d. body %v", err, resp.StatusCode, logBody(resp.Body, maxBodySize))
+			// to print the response, set the envvar BATON_DEBUG_PRINT_RESPONSE_BODY as non-empty, instead
+			return fmt.Errorf("failed to unmarshal JSON error response: %w. status code: %d", err, resp.StatusCode)
 		}
 
 		// Construct a more detailed error message
@@ -341,7 +337,12 @@ func (c *BaseHttpClient) Do(req *http.Request, options ...DoOption) (*http.Respo
 	}
 
 	// Replace resp.Body with a no-op closer so nobody has to worry about closing the reader.
-	resp.Body = io.NopCloser(bytes.NewBuffer(body))
+	shouldPrint := os.Getenv("BATON_DEBUG_PRINT_RESPONSE_BODY")
+	if shouldPrint != "" {
+		resp.Body = io.NopCloser(wrapPrintBody(bytes.NewBuffer(body)))
+	} else {
+		resp.Body = io.NopCloser(bytes.NewBuffer(body))
+	}
 
 	wresp := WrapperResponse{
 		Header:     resp.Header,