title: what "--from=builder" do in Dockerfile
body: <p>I am trying to understand the <a href="https://github.com/monzo/egress-operator/blob/master/Dockerfile#L24" rel="nofollow noreferrer">dockerfile</a> for implementing egress-operator. Can someone let me know what does line :</p>
  <p><code>COPY --from=builder /workspace/manager .</code> AND <code>ENTRYPOINT [&quot;/manager&quot;]</code> mean here and what are they trying to do at <code>ENTRYPOINT [&quot;/manager&quot;]</code> ?</p>
  <p>Are they running manager script then it should be something like <code>ENTRYPOINT [&quot;./manager&quot;]</code> or they are trying simply <code>cd</code> to <code>/manager</code> folder ?</p>