Make getting started guide faster

Signed-off-by: Stefan Scherer <[email protected]>

Dockerfile

@@ -5,20 +5,24 @@ WORKDIR /app
 COPY requirements.txt .
 RUN pip install -r requirements.txt
 
-# Run tests to validate app
 FROM node:12-alpine AS app-base
-RUN apk add --no-cache python g++ make
 WORKDIR /app
 COPY app/package.json app/yarn.lock ./
-RUN yarn install
 COPY app/spec ./spec
 COPY app/src ./src
+
+# Run tests to validate app
+FROM app-base AS test
+RUN apk add --no-cache python3 g++ make
+RUN yarn install
 RUN yarn test
 
 # Clear out the node_modules and create the zip
 FROM app-base AS app-zip-creator
-RUN rm -rf node_modules && \
-    apk add zip && \
+COPY app/package.json app/yarn.lock ./
+COPY app/spec ./spec
+COPY app/src ./src
+RUN apk add zip && \
     zip -r /app.zip /app
 
 # Dev-ready container - actual files will be mounted in