Automatically point to PR preview database

1

PR previews create a preview database. How can we automatically point our app to that?

The render.yaml has:

    envVars:
      - key: DATABASE_URL
        fromDatabase:
          name: staging
          property: connectionString

but I can’t think of a way to use previewValue to automagically point to the preview database since it’s created with an incremental number (of the PR) for the name.

How would you go about it?

2

Hey Oleg,

Welcome to the Render community!

I think you may be using https://render.com/docs/pull-request-previews, however you might want give Preview Environments | Render · Cloud Hosting for Developers a try as these will create a full environment for you and achieve what you want I think

3

Hey Oleg,

I am not a render.com staff, just one of their users. So, with a configuration looking something like this:

# render.yaml
previewsEnabled: true # this is important

databases:
  - name: staging
    plan: standard

services:
  - name: api
    type: web
    env: elixir
    envVars:
      - key: DATABASE_URL
        fromDatabase:
          name: staging
          property: connectionString
  # ...and so on

Your api service will have DATABASE_URL environment variable pointing to a staging DB normally, but for a preview environment (for a pull request), it will point to a PR version of that database created specifically for that PR. It’s done automatically. There’s nothing more you have to do on your side.

So for example in my Elixir application, I just need something like this and that is it.

# config/releases.exs
config :my_app, MyApp.Repo,
  adapter: Ecto.Adapters.Postgres,
  url: System.fetch_env!("DATABASE_URL")

Hope this helps.

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4

Thanks for the replies. Apologies for the lack of detail but I am using the previewsEnabled: true but that was master and hence this might have caused the misalignment. Just rebased my PR onto master and will keep you updated.

2 Likes
5

I am having other issues about the preview environment but this seems to be resolved as per @stefan.luptak reply, i.e. the preview environment automagically points to the preview database.

1 Like