¶Configuration

Two halves: elyra.toml, the project descriptor rata reads, and Config, the runtime facade your app reads.

¶elyra.toml

Ratatosk reads elyra.toml from the current directory or any parent (walking up). It describes where your app crate and frontend live, plus codegen, bundle, and database settings.

[app]
crate = "myapp"                  # the cargo package containing your App

[frontend]
dir = "app"                      # directory with package.json / vite

[codegen]
out = "app/src/bindings.ts"      # where `rata codegen` writes bindings
                                 # (default: "<frontend.dir>/src/bindings.ts")

[bundle]                         # optional; used by `rata bundle`
identifier = "com.example.myapp" # default: "com.example.<app.crate>"
name = "My App"                  # default: <app.crate>
version = "0.1.0"                # default: "0.1.0"
icon = "assets/icon.svg"         # source icon (.svg or raster)
deep_link = "myapp"              # registers myapp:// (Info.plist / .desktop)
description = "A demo app"       # Linux package metadata
maintainer = "Dev <dev@x.io>"    # .deb Maintainer:

[database]                       # optional; used by `rata migrate`
url = "sqlite://app.db?mode=rwc" # supports ${VAR} expansion; else $DATABASE_URL
migrations = "migrations"        # migrations directory (default: "migrations")

¶Sections

¶[app]

• crate (required) — the cargo package name of your binary. rata runs cargo run/build -p <crate>.

¶[frontend]

• dir (required) — folder containing package.json / vite.config.js.

¶[codegen]

• out — path for the generated bindings.ts.

¶[bundle]

• identifier, name, version — bundle metadata for rata bundle (macOS Info.plist, .deb control file, Windows folder name).
• icon — source icon; becomes AppIcon.icns on macOS and a hicolor icon in the .deb.
• deep_link — a custom URL scheme. Written to CFBundleURLTypes on macOS and MimeType=x-scheme-handler/<scheme> in the Linux .desktop entry. Pair it with App::deep_link("myapp"); without the bundle entry the OS never routes the URL to your app.
• description, maintainer — Linux package metadata.

¶[database]

• url — a connection URL; the scheme selects the driver (sqlite:, mysql:, postgres:). ${VAR} occurrences are expanded from the environment. If omitted, rata falls back to the DATABASE_URL env var.
• migrations — the migrations directory, relative to the project root.

¶Config at runtime

elyra.toml is a build/tooling descriptor; Config is what your app reads at runtime. Bind it with ConfigProvider and resolve it like any service:

use elyra::config::ConfigProvider;

App::new()
    .provider(ConfigProvider::new().with_default("app.theme", "dark"))
    .commands(commands![..])
    .run()

#[command]
async fn settings(ctx: Ctx) -> Vec<String> {
    let config = ctx.get::<elyra::Config>();
    let url = config.string("database.url").unwrap_or_default();
    let debug = config.bool("app.debug").unwrap_or(false);
    let port: u16 = config.get_or("server.port", 8080);
    let db = config.section("database"); // BTreeMap<String, String>
    vec![url, debug.to_string(), port.to_string(), db.len().to_string()]
}

¶Sources, lowest priority first

1. defaults registered with ConfigProvider::with_default / Config::default_value
2. elyra.toml (tables flattened to dotted keys: [app] crate → app.crate)
3. config/*.toml (the file stem prefixes its keys: config/services.toml [mail] from → services.mail.from)
4. .env
5. real process environment variables

A later source wins, so a shipped default can always be overridden by an env var without rebuilding.

¶Keys

Dotted and lowercase. Environment variables map in by lowercasing, dropping an ELYRA_ prefix and turning separators into dots:

${VAR} (and $VAR) inside a value is expanded from the environment, matching what rata already does for [database] url.

¶Accessors

raw · string · get::<T>() · get_or · bool (1/true/yes/on) · int · has · section(prefix) · all() · set · default_value.

¶Environment variables

ELYRA_DEV_URL and ELYRA_CODEGEN_OUT are normally set for you by the CLI; you rarely set them by hand.

¶Related

• Logging — ELYRA_LOG and the file sink
• Migrations — ELYRA_MIGRATE and seeders
• CLI · Security