mount: accessing states within jars

1. kafka-thing.clj

;; [tolitius:/tmp/ido]$ cat src/ido/core.clj
(ns ido.core
  (:require [mount.core :refer [defstate]]))

(defstate kafka :start 42
                :stop 0)

;; [tolitius:/tmp/ido]$
;; [tolitius:/tmp/ido]$ lein install
;; Created /private/tmp/ido/target/ido-0.1.0-SNAPSHOT.jar
;; Wrote /private/tmp/ido/pom.xml
;; Installed jar and pom into local repo.

;; ^^^ separate JAR / project

2. micro-service.clj

;; [tolitius:/tmp/micro-ido]$ cat project.clj
(defproject micro-ido "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.8.0"]
                 [mount "0.1.11-SNAPSHOT"]
                 [ido "0.1.0-SNAPSHOT"]])             ;; << depending on the "ido" jar we just created above
               
               
;; [tolitius:/tmp/micro-ido]$ cat src/micro_ido/core.clj

(ns micro-ido.core
  (:require [mount.core :refer [defstate]]
            [ido.core :refer [kafka]]))

(defn with-kafka [kafka-dep]
  (println "the ultimate kafka topic always has" kafka-dep "messages"))

(defstate micro-service :start (with-kafka kafka))

3. running-both.clj

;; [tolitius:/tmp/micro-ido]$ lein repl
;; nREPL server started on port 64400 on host 127.0.0.1 - nrepl://127.0.0.1:64400

user=> (require '[mount.core :as mount])

;; mount hasn't seen any states yet
user=> (mount/start)
{:started []}

;; now let's require the micro service
user=> (require '[micro-ido.core])
"|| mounting... #'ido.core/kafka"
"|| mounting... #'micro-ido.core/micro-service"
nil

;; ^^^ ok, so mound saw both, because micro-service _requires_ kafka, hence compiler saw it

;; let's kick it off
user=> (mount/start)
the ultimate kafka topic always has 42 messages
{:started ["#'ido.core/kafka" "#'micro-ido.core/micro-service"]}

;; great success :)