Heroku env variables $DATABASE_URL and $PORT not showing in dyno (heroku ps:exec)

Question

I've created a docker image and published it to heroku. For it to work properly I need the DATABASE_URL env variable. Postgres is provisioned to the app, and I can heroku config:get the db URL just fine. Yet after all is done I heroku ps:exec into my app, type 'env' and there is no $PORT or $DATABASE_URL, meaning my app cant get the db string.

the steps I took:

Github Action:

    - name: Build and deploy the Docker image
      env: 
        HEROKU_API_KEY: ${{ secrets.HEROKU_API_KEY }}
        APP_NAME: myApp
      run: |
        export DATABASE_URL=$(heroku config:get DATABASE_URL --app ${{ env.APP_NAME }})
        docker login --username=_ --password=${{ env.HEROKU_API_KEY }} registry.heroku.com
        docker build --build-arg DATABASE_URL_ARG=$DATABASE_URL -t registry.heroku.com/${{ env.APP_NAME }}/web .
        docker push registry.heroku.com/${{ env.APP_NAME }}/web

Dockerfile:

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS publish
WORKDIR /src
ARG DATABASE_URL_ARG
ENV DATABASE_URL=$DATABASE_URL_ARG
COPY . .
RUN dotnet tool install dotnet-ef && dotnet publish -c Release -o ./publish

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS runtime
ENV DATABASE_URL=$DATABASE_URL_ARG
WORKDIR /app
COPY --from=publish /src/publish .
CMD DATABASE_URL=${DATABASE_URL} dotnet app.dll

The build process is successful and the postgres db is seeded. I don't know if the second ENV is needed, its there as an artifact of me trying to make something work.

So the question is: where are the missing $PORT and $DATABASE_URL and how did I make them disappear?

Answer 1

Of course, this was a mistake on my part specific to heroku usage.

After you push your docker image to heroku, you run heroku container:release web I haven't done that, so I couldn't see my changes. As per documentation, $DATABASE_URL, and $PORT and added to the environment automatically and are available at runtime.