diff --git a/.docker/Dockerfile b/.docker/Dockerfile
index b8b774f..8428b93 100644
--- a/.docker/Dockerfile
+++ b/.docker/Dockerfile
@@ -1,5 +1,5 @@
 # Start with a base image containing golang runtime
-FROM golang:1.20
+FROM golang:1.21
 
 # Set the working directory in the container
 WORKDIR /go/src/app
@@ -10,6 +10,16 @@ COPY go.mod go.sum ./
 # Download the dependencies
 RUN go mod download
 
+# Install gcloud CLI
+RUN apt-get update && apt-get install -y \
+    curl \
+    apt-transport-https \
+    ca-certificates && \
+    echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list && \
+    curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key --keyring /usr/share/keyrings/cloud.google.gpg add - && \
+    apt-get update && apt-get install -y google-cloud-sdk google-cloud-cli-app-engine-go && \
+    rm -rf /var/lib/apt/lists/*
+
 # Copy the current directory contents into the container at /go/src/app
 COPY ../ .
 
diff --git a/gae/app.yaml b/gae/app.yaml
index e72bad9..a6f25f5 100644
--- a/gae/app.yaml
+++ b/gae/app.yaml
@@ -1,9 +1,9 @@
-runtime: go120
+runtime: go121
 app_engine_apis: true
 automatic_scaling:
-    max_idle_instances: 1
-    max_concurrent_requests: 100
+  max_idle_instances: 1
+  max_concurrent_requests: 100
 
 handlers:
-- url: /.*
-  script: auto
+  - url: /.*
+    script: auto
diff --git a/gae/router.go b/gae/router.go
index 56309e0..ff1fa50 100644
--- a/gae/router.go
+++ b/gae/router.go
@@ -171,9 +171,9 @@ func main() {
 	r.Methods("OPTIONS").HandlerFunc(preflight)
 	variants := r.Path("/{variant}").Subrouter()
 	variants.Methods("POST").HandlerFunc(resolve)
-	variants.Path("/resolve-with-options").Methods("POST").HandlerFunc(resolveWithOptions)
 	variants.Methods("GET").HandlerFunc(start)
 	r.Path("/start-with-options/{variant}").Methods("GET").HandlerFunc(startWithOptions)
+	r.Path("/resolve-with-options/{variant}").Methods("POST").HandlerFunc(resolveWithOptions)
 	r.Path("/").HandlerFunc(listVariants)
 	http.Handle("/", r)
 	appengine.Main()