How do you update the app.json manifest on a running heroku app?

Question

I am using Heroku Pipelines connected to GitHub.

I have three different environments: - Reviews (where all my pull requests are automatically deployed to once my CI tests are successful) - Staging (where my master branch is deployed to) - Production (my production environment)

My Review apps are created and destroyed as I pull and merge branches. My Staging and Production apps are always the same. Staging gets updated when my master branch is updated, and then I can manually decide to promote that code to Production.

This is all great! Except I am facing a issue with my app.json file.

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 app.json file. Example:

"addons": [
  "logentries:le_tryit",
  "newrelic:wayne",
  {
    "plan": "mongolab:sandbox",
    "as": "MONGODB_URI"
  },
  {
    "plan": "heroku-redis:hobby-dev",
    "as": "REDIS_SESSIONS_URI"
  }
]

Once a create a pull request, a app is created in Reviews and I can see my new addons. Unfortunately, when I merge my branch with master, app.json doesn't seem to run again on my Staging environment (and subsequently in my Production environment.

Is there a way to re-run the app.json manifest in an existing heroku app? and can they be automated with each new deploy?

If not, are there reasons for this?

Thanks!

Answer 1

There is no way to do what you're asking. The app.json is only parsed when creating a new Heroku app, not when re-deploying one. The reason is that it could cause unwanted side effects to a production application.

EG: What would happen if you remove a line from the app.json file and push that to an existing Heroku app? Should Heroku delete your addon (potentially destroying lots of data?)

Instead, what you should do is this: when you cut a production release, if you need to use new addons or change them, do it via the CLI manually.

For instance:

$ heroku addons:create heroku-redis