title: How do you update the app.json manifest on a running heroku app?
body: <p>I am using Heroku Pipelines connected to GitHub.</p>
  
  <p>I have three different environments:
  - <code>Reviews</code> (where all my pull requests are automatically deployed to once my CI tests are successful)
  - <code>Staging</code> (where my master branch is deployed to)
  - <code>Production</code> (my production environment)</p>
  
  <p>My <code>Review</code> apps are created and destroyed as I pull and merge branches. My <code>Staging</code> and <code>Production</code> apps are always the same. <code>Staging</code> gets updated when my master branch is updated, and then I can manually decide to promote that code to <code>Production</code>.</p>
  
  <p>This is all great! Except I am facing a issue with my <code>app.json</code> file.</p>
  
  <p>When developing new branches, I often use new heroku addons i.e. a Redis db or new monitoring tools. I do this by updating my <code>app.json</code> file. Example:</p>
  
  <pre><code>"addons": [
    "logentries:le_tryit",
    "newrelic:wayne",
    {
      "plan": "mongolab:sandbox",
      "as": "MONGODB_URI"
    },
    {
      "plan": "heroku-redis:hobby-dev",
      "as": "REDIS_SESSIONS_URI"
    }
  ]
  </code></pre>
  
  <p>Once a create a pull request, a app is created in <code>Reviews</code> and I can see my new addons. Unfortunately, when I merge my branch with master, <code>app.json</code> doesn't seem to run again on my <code>Staging</code> environment (and subsequently in my <code>Production</code> environment.  </p>
  
  <p>Is there a way to re-run the <code>app.json</code> manifest in an existing heroku app? and can they be automated with each new deploy?</p>
  
  <p>If not, are there reasons for this?</p>
  
  <p>Thanks!</p>