Day 1 · Step 4 — Configure the DB connection (no redeploy)

cd up-api
dotnet add package Npgsql.EntityFrameworkCore.PostgreSQL
dotnet add package Microsoft.EntityFrameworkCore.Design

appsettings.Development.json:

{
  "ConnectionStrings": {
    "Default": "Host=localhost;Port=5432;Database=up_db;Username=upadmin;Password=uppass"
  }
}

Use localhost here because EF CLI commands (next steps) run from the host. Inside the up-api container the connection string instead uses the compose service name db — that's already set in the container's environment from the docker-deploy step, don't change it.