Add echo handler with backend propagation

pkg/api/echo.go

@@ -0,0 +1,79 @@
+package api
+
+import (
+	"bytes"
+	"context"
+	"io/ioutil"
+	"net/http"
+	"github.com/stefanprodan/k8s-podinfo/pkg/version"
+	"go.uber.org/zap"
+)
+
+func (s *Server) echoHandler(w http.ResponseWriter, r *http.Request) {
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		s.logger.Error("reading the request body failed", zap.Error(err))
+		s.ErrorResponse(w, r, "invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	if len(s.config.BackendURL) > 0 {
+		backendReq, err := http.NewRequest("POST", s.config.BackendURL, bytes.NewReader(body))
+		if err != nil {
+			s.logger.Error("backend call failed", zap.Error(err), zap.String("url", s.config.BackendURL))
+			s.ErrorResponse(w, r, "backend call failed", http.StatusInternalServerError)
+			return
+		}
+
+		// forward headers
+		copyTracingHeaders(r, backendReq)
+
+		backendReq.Header.Set("X-API-Version", version.VERSION)
+		backendReq.Header.Set("X-API-Revision", version.REVISION)
+
+		ctx, cancel := context.WithTimeout(backendReq.Context(), s.config.HttpClientTimeout)
+		defer cancel()
+
+		// call backend
+		resp, err := http.DefaultClient.Do(backendReq.WithContext(ctx))
+		if err != nil {
+			s.logger.Error("backend call failed", zap.Error(err), zap.String("url", s.config.BackendURL))
+			s.ErrorResponse(w, r, "backend call failed", http.StatusInternalServerError)
+			return
+		}
+
+		defer resp.Body.Close()
+
+		// copy error status from backend and exit
+		if resp.StatusCode >= 400 {
+			s.ErrorResponse(w, r, "backend error", resp.StatusCode)
+			return
+		}
+
+		// forward the received body
+		rbody, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			s.logger.Error(
+				"reading the backend request body failed",
+				zap.Error(err),
+				zap.String("url", s.config.BackendURL))
+			s.ErrorResponse(w, r, "backend call failed", http.StatusInternalServerError)
+			return
+		}
+
+		s.logger.Debug(
+			"payload received from backend",
+			zap.String("response", string(rbody)),
+			zap.String("url", s.config.BackendURL))
+
+		w.Header().Set("X-Color", s.config.UIColor)
+		w.WriteHeader(http.StatusAccepted)
+		w.Write(rbody)
+	} else {
+		w.Header().Set("X-Color", s.config.UIColor)
+		w.WriteHeader(http.StatusAccepted)
+		w.Write(body)
+	}
+}
+
+

pkg/api/echo_test.go

@@ -0,0 +1,34 @@
+package api
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"strings"
+)
+
+func TestEchoHandler(t *testing.T) {
+	expected := `{"test": true}`
+	req, err := http.NewRequest("POST", "/api/echo", strings.NewReader(expected))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	srv := NewMockServer()
+	handler := http.HandlerFunc(srv.echoHandler)
+
+	handler.ServeHTTP(rr, req)
+
+	// Check the status code is what we expect.
+	if status := rr.Code; status != http.StatusAccepted {
+		t.Errorf("handler returned wrong status code: got %v want %v",
+			status, http.StatusAccepted)
+	}
+
+	// Check the response body is what we expect.
+	if rr.Body.String() != expected {
+		t.Fatalf("handler returned unexpected body:\ngot \n%v \nwant \n%s",
+			rr.Body.String(), expected)
+	}
+}