title: Deploy Docker, problems parsing your heroku.yml: empty
body: <p>I trying to deploy a React App on heroku with a heroku.yml using a Dockerfile.
  But whe i try to deploy it, i get &quot;problems parsing your heroku.yml&quot; with no error</p>
  <p>front/Dockerfile</p>
  <pre><code>WORKDIR /app
  COPY package.json ./
  COPY yarn.lock ./
  RUN yarn install --frozen-lockfile
  COPY . .
  RUN yarn build
  
  FROM nginx:1.19-alpine AS server
  COPY ./etc/nginx.conf /etc/nginx/conf.d/default.conf
  COPY --from=builder ./app/build /usr/share/nginx/html
  CMD [&quot;nginx&quot;, &quot;-g&quot;, &quot;daemon off;&quot;]
  </code></pre>
  <p>heroku.yml</p>
  <pre><code>build:
    docker:
      release:
          dockerfile: ./front/Dockerfile
          target: builder
      run:
          dockerfile: ./front/Dockerfile
          target: server
  release:
    image: builder
  run:
    image:
      command:
      image: server
  </code></pre>
  <p>Error on build log:</p>
  <pre><code>=== Fetching app code
  =!= There were problems parsing your heroku.yml. We've detected the following issues:
  </code></pre>
  <p>I don't understand why i get that.</p>