1.1.0 docs





    Mar 28, 2018

    Tampere, Helsinki, Finland


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    The README below is fetched from the published project artifact. Some relative links may be broken.

    Maailma Build Status

    Clojars Project

    API Docs.

    Project statement

    Unlike more general of our libraries (like compojure-api and ring-swagger) this project is primarily intended for use in Metosin’s projects. Feel free to use, but don’t expect full support.

    • We might remove features if we think they are not useful anymore
    • We will reject PRs and issues about features we wouldn’t use ourselves


    • Represents application configuration as a single map which is read once on startup
    • Reads configuration from multiple sources and recursively merges it
      • EDN files in classpath – shipped with JAR, useful for default options
      • EDN files in filesystem – created by hand or by deploy tooling
      • Environment variables
      • Java properties
      • Override parameter – useful for overriding options for test systems
      • User selects the sources themselves
      • Extendable with functions
    • EDN readers can be provided as option, which allows use with Integrant


    (ns backend.system
      (:require [maailma.core :as m]))
    (defn system [override]
      (let [env (m/build-config
                  (m/resource "config-defaults.edn")
                  (m/env "prefix")
                  (m/env-var "SERVER_PORT" [:http :port])
                  (m/properties "prefix")
                  (m/file "./config-local.edn")

    Integrant example

    Add reader options to resource and file calls:

        (m/resource "config.edn" {:readers {'ig/ref ig/ref}})
        (m/file "config-local.edn" {:readers {'ig/ref ig/ref}})))

    (Not supported with read-config! function)


    • Is it necessary to refresh configuration of running application?
      • Most fixes done to running production systems over REPL are very small fixes to integration logic
      • It’s possible that some integration settings need to be changed quickly?
      • Probably not necessary. Most logic is isolated to pure functions and the can be replaced over REPL without touching components or configuration.


    Copyright © 2015-2018 Metosin Oy.

    Distributed under the Eclipse Public License, the same as Clojure.