Configuration

Invirt is a singleton object. The framework is initialised through Invirt.configure(...) which sets development mode and customises the Pebble template engine used to render views.

object Invirt {

    fun configure(
        developmentMode: Boolean = Environment.ENV.developmentMode,
        pebble: InvirtPebbleConfig = InvirtPebbleConfig()
    )
}

The first reference to Invirt triggers a default configuration via its init block, so for the simplest applications no explicit call is required. Calling Invirt.configure(...) is needed when you want to override the defaults — for example to register Pebble extensions or change the template classpath location. Configuration is global; call configure(...) once during application startup, before serving any requests.

fun main() {
    Invirt.configure(
        developmentMode = Environment.ENV.developmentMode,
        pebble = InvirtPebbleConfig(
            classpathLocation = "webapp/views",
            extensions = listOf(/* ... */),
            globalVariables = mapOf("staticAssetsVersion" to gitCommitId())
        )
    )

    val server = Netty(8080).toServer(routes(/* ... */)).start()
}

Pebble configuration

InvirtPebbleConfig holds the settings for the Pebble template engine.

class InvirtPebbleConfig(
    val classpathLocation: String = "webapp/views",
    val hotReloadDirectory: String = "src/main/resources/webapp/views",
    val extensions: List<Extension> = emptyList(),
    val globalVariables: Map<String, Any> = emptyMap(),
    val contextVariables: Map<String, (Request) -> Any?> = emptyMap()
)

• classpathLocation — classpath path where templates are loaded from when developmentMode is false.
• hotReloadDirectory — filesystem path where templates are loaded from when developmentMode is true.
• extensions — custom Pebble Extension instances. See the security-authentication example for an application using a custom Pebble extension.
• globalVariables — variables available in every Pebble template. Useful for application-wide constants like a static assets version.
• contextVariables — per-request variables computed from the current Request and exposed to the template. The lambda is invoked at render time with the request that produced the response.

Development mode

developmentMode controls template loading:

• true — templates are loaded from hotReloadDirectory with no caching, so edits to a template are visible immediately on a browser refresh. Typically used during local development.
• false — templates are loaded from classpathLocation with http4k's caching template loader. Typically used in production.

By default developmentMode is read from the DEVELOPMENT_MODE environment variable (see Environment.developmentMode) and defaults to false when the variable is not set.