HTTP status echo server for auth gateway catchall

src/go/cmd/status-echo-server/BUILD.bazel

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+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library", "go_test")
+load("@rules_oci//oci:defs.bzl", "oci_image")
+load("@rules_pkg//pkg:tar.bzl", "pkg_tar")
+
+package(default_visibility = ["//visibility:public"])
+
+go_library(
+    name = "go_default_library",
+    srcs = ["main.go"],
+    importpath = "github.com/googlecloudrobotics/core/src/go/cmd/status-echo-server",
+    visibility = ["//visibility:private"],
+    deps = [
+        "@com_github_googlecloudrobotics_ilog//:go_default_library",
+    ],
+)
+
+go_binary(
+    name = "status-echo-server-app",
+    embed = [":go_default_library"],
+)
+
+pkg_tar(
+    name = "status-echo-server-image-layer",
+    srcs = [":status-echo-server-app"],
+    extension = "tar.gz",
+)
+
+oci_image(
+    name = "status-echo-server-image",
+    base = "@distroless_base",
+    entrypoint = ["/status-echo-server-app"],
+    tars = [":status-echo-server-image-layer"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["main_test.go"],
+    embed = [":go_default_library"],
+)

src/go/cmd/status-echo-server/main.go

@@ -0,0 +1,76 @@
+// Copyright 2026 The Cloud Robotics Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package main runs a multiplexing HTTP relay server.
+//
+// It exists to make HTTP endpoints on robots accessible without a public
+// endpoint. It binds to a public endpoint accessible by both user-client and
+// backend and works together with a relay-client that's colocated with the
+// backend.
+//
+// For more details, see README.md.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/googlecloudrobotics/ilog"
+)
+
+var (
+	port       = flag.Int("port", 80, "Port number to listen on")
+	httpStatus = flag.Int("http_status", 200, "HTTP Status to echo")
+	logLevel   = flag.Int("log_level", int(slog.LevelInfo), "the log message level required")
+)
+
+func echoHandler(w http.ResponseWriter, req *http.Request) {
+	slog.Debug("echo", slog.String("path", req.URL.Path))
+	w.Header().Set("Content-Type", "text/plain")
+	w.WriteHeader(*httpStatus)
+	w.Write([]byte(http.StatusText(*httpStatus)))
+}
+
+func main() {
+	flag.Parse()
+
+	// Setup logger
+	logHandler := ilog.NewLogHandler(slog.Level(*logLevel), os.Stderr)
+	slog.SetDefault(slog.New(logHandler))
+
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", echoHandler)
+
+	addr := fmt.Sprintf(":%d", *port)
+
+	srv := &http.Server{
+		Addr:         addr,
+		Handler:      mux, 
+		ReadTimeout:  1 * time.Second,  
+		WriteTimeout: 2 * time.Second,
+		IdleTimeout:  10 * time.Second,
+	}
+
+	slog.Info("Status echo server running", slog.String("address", addr))
+	if err := srv.ListenAndServe(); err != nil {
+		slog.Error("Server failed to start", slog.Any("error", err))
+		os.Exit(1)
+	}
+}

src/go/cmd/status-echo-server/main_test.go

@@ -0,0 +1,79 @@
+// Copyright 2026 The Cloud Robotics Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestEchoHandler(t *testing.T) {
+	tests := []struct {
+		desc       string
+		path       string
+		httpStatus int
+		wantStatus int
+		wantBody   string
+	}{
+		{
+			desc:       "OK status on root path",
+			path:       "/",
+			httpStatus: http.StatusOK,
+			wantStatus: http.StatusOK,
+			wantBody:   "OK",
+		},
+		{
+			desc:       "Internal Server Error on nested path",
+			path:       "/foo/bar?key=value",
+			httpStatus: http.StatusInternalServerError,
+			wantStatus: http.StatusInternalServerError,
+			wantBody:   "Internal Server Error",
+		},
+		{
+			desc:       "OK status on deep path",
+			path:       "/a/b/c/d/e",
+			httpStatus: http.StatusOK,
+			wantStatus: http.StatusOK,
+			wantBody:   "OK",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			*httpStatus = tc.httpStatus
+
+			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
+			w := httptest.NewRecorder()
+
+			echoHandler(w, req)
+
+			resp := w.Result()
+			if resp.StatusCode != tc.wantStatus {
+				t.Errorf("got %d, want %d", resp.StatusCode, tc.wantStatus)
+			}
+
+			contentType := resp.Header.Get("Content-Type")
+			if contentType != "text/plain" {
+				t.Errorf("got %q, want %q", contentType, "text/plain")
+			}
+
+			body := w.Body.String()
+			if body != tc.wantBody {
+				t.Errorf("got %q, want %q", body, tc.wantBody)
+			}
+		})
+	}
+}