title: Build docker in ASP.NET Core: "no such file or directory" error
body: <p>I'm getting an error when I build my docker.</p>
  
  <pre><code>Sending build context to Docker daemon 3.584 kB
  Step 1/8 : FROM microsoft/aspnetcore:1.1
   ---&gt; 2628aaa7b8cf
  Step 2/8 : ENV ASPNETCORE_URLS "http://*:5000"
   ---&gt; Using cache
   ---&gt; 5dffde204fef
  Step 3/8 : ENV ASPNETCORE_ENVIRONMENT "Development"
   ---&gt; Using cache
   ---&gt; 3064358bc0eb
  Step 4/8 : ARG source
   ---&gt; Using cache
   ---&gt; 4159d0eb78c0
  Step 5/8 : WORKDIR /app
   ---&gt; Using cache
   ---&gt; 61a394c84304
  Step 6/8 : EXPOSE 5000
   ---&gt; Using cache
   ---&gt; c7c2309f7085
  Step 7/8 : COPY ${source:-obj/Docker/publish} .
  lstat obj/Docker/publish: no such file or directory
  </code></pre>
  
  <p>Here's my Dockerfile.</p>
  
  <pre><code>FROM microsoft/aspnetcore:1.1
  ENV ASPNETCORE_URLS="http://*:5000"
  ENV ASPNETCORE_ENVIRONMENT="Development"
  ARG source
  WORKDIR /app
  EXPOSE 5000
  COPY ${source:-obj/Docker/publish} .
  ENTRYPOINT ["dotnet", "ProjectTestApi.dll"
  </code></pre>
  
  <p>and I run a command: </p>
  
  <pre><code>$ docker build -t my-docker-image-test .
  </code></pre>
  
  <p>Do you have any ide what is wrong?</p>