title: How do I set the canonical header to a HTTP response?
body: <p>I know that I can add a tag to the html head</p>
  
  <pre><code>&lt;link rel="canonical" href="https://geoffkenyon.com/how-to-add-canonical-tag-to-http-headers"&gt;
  </code></pre>
  
  <p>But I want to add this information in a HTTP response header instead. What header key and value would the above tag translate to?</p>
  
  <p>I plan to do this in nginx as:</p>
  
  <pre><code>location /old-link {
      add_header key value;
  }
  </code></pre>