ccn/Services/Website/Sources/App/App.swift

import Configuration
import Hummingbird

/// The entry point of the website executable.
///
/// Loads the configuration, then either serves the website or — when the `database.migrate` flag is set — runs the registered migrations against the
/// configured backend and exits.
@main
struct App {

    /// Loads the configuration and runs the mode it selects.
    ///
    /// The configuration is read from the providers in precedence order: command-line arguments first, then process environment variables, then a
    /// `.env.local` file when one is present, then a `.env` file when one is present, and finally the in-memory defaults.
    static func main() async throws {
        let reader = try await ConfigReader(
            providers: [
                CommandLineArgumentsProvider(),
                EnvironmentVariablesProvider(),
                EnvironmentVariablesProvider(
                    environmentFilePath: ".env.local",
                    allowMissing: true
                ),
                EnvironmentVariablesProvider(
                    environmentFilePath: ".env",
                    allowMissing: true
                ),
                InMemoryProvider(values: [
                    .HTTP.serverName: .HTTP.serverName
                ]),
            ]
        )

        // Migrate-and-exit mode runs the registered migrations against the configured backend and returns, so a shared
        // database is migrated by a single deliberate invocation (`--database-migrate`) rather than by every booting
        // instance.
        guard !reader.migrate else {
            try await migration(
                reader: reader
            )

            return
        }

        let app = await application(
            reader: reader
        )

        try await app.runService()
    }

}