Init

internal/proxy/reverse.go

@@ -0,0 +1,33 @@
+package proxy
+
+import (
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"strings"
+)
+
+// NewReverseProxy builds a reverse proxy to target base URL with path rewriting:
+// stripPrefix (/api/{alias}) + pathPrefix (/v1) + remainder.
+func NewReverseProxy(target *url.URL, stripPrefix, pathPrefix string, setAuth string) *httputil.ReverseProxy {
+	proxy := httputil.NewSingleHostReverseProxy(target)
+	orig := proxy.Director
+	proxy.Director = func(req *http.Request) {
+		orig(req)
+		p := req.URL.Path
+		if strings.HasPrefix(p, stripPrefix) {
+			rest := strings.TrimPrefix(p, stripPrefix)
+			rest = strings.TrimPrefix(rest, "/")
+			if rest == "" {
+				req.URL.Path = pathPrefix
+			} else {
+				req.URL.Path = pathPrefix + "/" + rest
+			}
+			req.URL.RawPath = ""
+		}
+		if setAuth != "" {
+			req.Header.Set("Authorization", setAuth)
+		}
+	}
+	return proxy
+}

internal/proxy/reverse_test.go

@@ -0,0 +1,26 @@
+package proxy
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+)
+
+func TestReverseProxyPathRewrite(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/v1/health" {
+			t.Fatalf("path %q", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer srv.Close()
+	up, _ := url.Parse(srv.URL)
+	rp := NewReverseProxy(up, "/api/main_srv", "/v1", "")
+	req := httptest.NewRequest(http.MethodGet, "/api/main_srv/health", nil)
+	rec := httptest.NewRecorder()
+	rp.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status %d", rec.Code)
+	}
+}