diff --git a/Dockerfile b/Dockerfile
deleted file mode 100644
index 06c09cc..0000000
--- a/Dockerfile
+++ /dev/null
@@ -1,13 +0,0 @@
-FROM node:12-alpine
-
-WORKDIR /excalidraw-room
-
-COPY package.json yarn.lock ./
-RUN yarn
-
-COPY tsconfig.json ./
-COPY src ./src
-RUN yarn build
-
-EXPOSE 80
-CMD ["yarn", "start"]
diff --git a/app.yaml b/app.yaml
index 7fde67a..27c93bb 100644
--- a/app.yaml
+++ b/app.yaml
@@ -1 +1,12 @@
 runtime: nodejs14
+env: flex
+
+# https://cloud.google.com/appengine/docs/flexible/nodejs/configuring-your-app-with-app-yaml
+manual_scaling:
+  instances: 1
+resources:
+  cpu: 1
+  memory_gb: 0.5
+  disk_size_gb: 10
+network:
+  session_affinity: true
diff --git a/src/index.ts b/src/index.ts
index 9b43145..2744244 100755
--- a/src/index.ts
+++ b/src/index.ts
@@ -22,10 +22,10 @@ server.listen(port, () => {
 
 const io = socketIO(server, {
   handlePreflightRequest: function (req, res) {
+    console.log('req', req.header);
     var headers = {
       "Access-Control-Allow-Headers": "Content-Type, Authorization",
-      "Access-Control-Allow-Origin":
-        (req.header && req.header.origin) || "https://excalidraw.com",
+      "Access-Control-Allow-Origin": "*",
       "Access-Control-Allow-Credentials": true,
     };
     res.writeHead(200, headers);