Fixes open-policy-agent#5310

server/handlers/compress.go

@@ -5,6 +5,7 @@ import (
 	"compress/gzip"
 	"fmt"
 	"io"
+	"log"
 	"net/http"
 	"strings"
 	"sync"
@@ -54,7 +55,10 @@ func CompressHandler(handler http.Handler) http.Handler {
 		defer func() {
 			gzipWriter.Close()
 			responseWriter.Header().Set("Content-Length", fmt.Sprint(len(b.Bytes())))
-			responseWriter.Write(b.Bytes())
+			_, err := responseWriter.Write(b.Bytes())
+			if err != nil {
+				log.Fatalf("Error writing the compressed response: %v", err)
+			}
 		}()
 
 		crw := &compressResponseWriter{Writer: gzipWriter, ResponseWriter: responseWriter}

server/handlers/compress_test.go

@@ -19,7 +19,10 @@ const (
 func executeRequest(w *httptest.ResponseRecorder, path string, acceptEncoding string) {
 	CompressHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
-		io.WriteString(w, requestBody)
+		_, err := io.WriteString(w, requestBody)
+		if err != nil {
+			log.Fatalf("Error writing the request body: %v", err)
+		}
 	})).ServeHTTP(w, &http.Request{
 		URL:    &url.URL{Path: path},
 		Method: "GET",

server/server.go

@@ -3013,7 +3013,9 @@ func annotateSpan(ctx context.Context, decisionID string) {
 func readPlainBody(r *http.Request) (io.ReadCloser, error) {
 	if strings.Contains(r.Header.Get("Content-Encoding"), "gzip") {
 		plainBody, err := gzip.NewReader(r.Body)
-		defer plainBody.Close()
+		if err != nil {
+			defer plainBody.Close()
+		}
 		return plainBody, err
 	}
 	return r.Body, nil

server/server_test.go

@@ -1939,7 +1939,7 @@ allow_request { flag == true }
 	f.server.Handler.ServeHTTP(f.recorder, req)
 
 	expected := "true"
-	result := strings.TrimSuffix(string(f.recorder.Body.Bytes()), "\n")
+	result := strings.TrimSuffix(f.recorder.Body.String(), "\n")
 	if result != expected {
 		t.Fatalf("Expected %v but got: %v", expected, result)
 	}