Trait DfeApp 

pub trait DfeApp: Sized {
    type Config: DeserializeOwned + Debug + Send + Sync;

    // Required methods
    fn name(&self) -> &str;
    fn env_prefix(&self) -> &str;
    fn version_info(&self) -> VersionInfo;
    fn common_args(&self) -> &CommonArgs;
    fn load_config(&self, path: Option<&str>) -> Result<Self::Config, CliError>;
    fn run_service(
        &self,
        config: Self::Config,
        runtime: ServiceRuntime,
    ) -> impl Future<Output = Result<(), CliError>> + Send;

    // Provided methods
    fn command(&self) -> Option<&StandardCommand> { ... }
    fn scaling_components(
        &self,
        _config: &Self::Config,
    ) -> Vec<ScalingComponent> { ... }
    fn register_metrics(&self, _manager: &MetricsManager) { ... }
    fn deployment_contract(&self) -> Option<DeploymentContract> { ... }
}

Available on crate feature cli only.

Trait for DFE service applications.

Implement this trait to get the standard CLI lifecycle for free. The 80% common behaviour (logging, config, metrics, version) is handled by run_app(). Your app provides the 20% (config type, service logic).

Required Associated Types

type Config: DeserializeOwned + Debug + Send + Sync

Application-specific configuration type.

Required Methods

fn name(&self) -> &str

Service name (e.g. “dfe-loader”).

fn env_prefix(&self) -> &str

Environment variable prefix for config cascade (e.g. “DFE_LOADER”).

fn version_info(&self) -> VersionInfo

Version information for this service.

fn common_args(&self) -> &CommonArgs

Access the common CLI arguments.

fn load_config(&self, path: Option<&str>) -> Result<Self::Config, CliError>

Load application configuration from the given path (or defaults).

Errors

Returns CliError if configuration cannot be loaded or parsed.

fn run_service( &self, config: Self::Config, runtime: ServiceRuntime, ) -> impl Future<Output = Result<(), CliError>> + Send

Run the main service loop.

Called after logging, config, and ServiceRuntime are initialised. The runtime contains all common infrastructure (metrics, memory guard, shutdown token, worker pool, scaling pressure). Apps just use it – no boilerplate needed.

Errors

Returns CliError if the service encounters a fatal error.

Provided Methods

fn command(&self) -> Option<&StandardCommand>

Resolve the active subcommand.

Returns None to default to StandardCommand::Run.

fn scaling_components(&self, _config: &Self::Config) -> Vec<ScalingComponent>

Available on crate feature scaling only.

Provide scaling pressure components for KEDA autoscaling.

Override to register app-specific scaling signals (buffer depth, consumer lag, error rate, etc.). The default returns an empty vec.

fn register_metrics(&self, _manager: &MetricsManager)

Available on crate features metrics or otel-metrics only.

Register all metrics for this service.

Called by metrics-manifest and generate-artefacts subcommands to capture the full metric catalogue without starting the service. The default implementation is a no-op. Override to register DfeMetrics, metric groups, and app-specific metrics.

fn deployment_contract(&self) -> Option<DeploymentContract>

Available on crate feature deployment only.

Build the deployment contract for this service.

Called by generate-artefacts to produce container specs, health endpoints, KEDA config, and metrics manifest. The default returns None. Override to provide a contract.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors