title: spring-boot:build-image behind a proxy
body: <p>I'm trying to follow building a docker image with spring boot 2.3.0 from behind a proxy.</p>
  
  <p>According to the docs <a href="https://docs.spring.io/spring-boot/docs/2.3.0.RELEASE/maven-plugin/reference/html/#build-image-example-builder-configuration" rel="nofollow noreferrer">https://docs.spring.io/spring-boot/docs/2.3.0.RELEASE/maven-plugin/reference/html/#build-image-example-builder-configuration</a> I need something like</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;plugin&gt;
    &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
    &lt;artifactId&gt;spring-boot-maven-plugin&lt;/artifactId&gt;
    &lt;version&gt;2.3.0.RELEASE&lt;/version&gt;
    &lt;configuration&gt;
      &lt;image&gt;
        &lt;env&gt;
          &lt;HTTP_PROXY&gt;http://proxy.example.com&lt;/HTTP_PROXY&gt;
          &lt;HTTPS_PROXY&gt;https://proxy.example.com&lt;/HTTPS_PROXY&gt;
        &lt;/env&gt;
      &lt;/image&gt;
    &lt;/configuration&gt;
  &lt;/plugin&gt;
  </code></pre>
  
  <p>But I couldn't get that to work. However I could get it to work when prefixing the variables with BPL_ like below</p>
  
  <pre><code>&lt;plugin&gt;
    &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
    &lt;artifactId&gt;spring-boot-maven-plugin&lt;/artifactId&gt;
    &lt;version&gt;2.3.0.RELEASE&lt;/version&gt;
    &lt;configuration&gt;
      &lt;image&gt;
        &lt;env&gt;
          &lt;BPL_HTTP_PROXY&gt;http://proxy.example.com&lt;/BPL_HTTP_PROXY&gt;
          &lt;BPL_HTTPS_PROXY&gt;https://proxy.example.com&lt;/BPL_HTTPS_PROXY&gt;
        &lt;/env&gt;
      &lt;/image&gt;
    &lt;/configuration&gt;
  &lt;/plugin&gt;
  </code></pre>
  
  <p>So it this a bug, or something that I don't understand.</p>
  
  <p>Even better, could this be specified outside the pom like from command line? I'm using powershell.</p>