Add GAE app frontend to serve custom domain traffic

fwd/.gcloudignore

@@ -0,0 +1,25 @@
+# This file specifies files that are *not* uploaded to Google Cloud Platform
+# using gcloud. It follows the same syntax as .gitignore, with the addition of
+# "#!include" directives (which insert the entries of the given .gitignore-style
+# file at that point).
+#
+# For more information, run:
+#   $ gcloud topic gcloudignore
+#
+.gcloudignore
+# If you would like to upload your .git directory, .gitignore file or files
+# from your .gitignore file, remove the corresponding line
+# below:
+.git
+.gitignore
+
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+# Test binary, build with `go test -c`
+*.test
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out

fwd/app.go

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+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+)
+
+const appJunk = "https://app-j33hbo5ywa-uc.a.run.app"
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		req, err := http.NewRequest(r.Method, fmt.Sprintf("%s/%s", appJunk, r.URL.Path), nil)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		for k, v := range resp.Header {
+			w.Header().Set(k, v[0])
+		}
+		w.WriteHeader(resp.StatusCode)
+		io.Copy(w, resp.Body)
+	})
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

fwd/app.yaml

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+runtime: go111
+