using the "--help" param

project.clj

@@ -15,4 +15,13 @@
   :profiles {:dev {:source-paths ["dev" "test/app"]
                    :dependencies [[yesql "0.5.1"]
                                   [org.clojure/tools.nrepl "0.2.11"]
-                                  [com.datomic/datomic-free "0.9.5327" :exclusions [joda-time]]]}})
+                                  [org.clojure/tools.cli "0.3.3"]
+                                  [com.datomic/datomic-free "0.9.5327" :exclusions [joda-time]]]}
+
+             ;; "test" is in sources here to just "demo" the uberjar without poluting mount "src"
+             :uberjar {:source-paths ["test/app"]
+                       :dependencies [[org.clojure/tools.cli "0.3.3"]
+                                      [org.clojure/tools.nrepl "0.2.11"]
+                                      [com.datomic/datomic-free "0.9.5327" :exclusions [joda-time]]]
+                       :main app
+                       :aot :all}})

src/mount/mount.clj

@@ -7,6 +7,7 @@
 
 ;; (defonce ^:private session-id (System/currentTimeMillis))
 (defonce ^:private mount-state 42)
+(defonce ^:private -args (atom :no-args))                  ;; mostly for command line args and external files
 (defonce ^:private state-seq (atom 0))
 (defonce ^:private state-order (atom {}))
 
@@ -57,6 +58,9 @@
           (throw (RuntimeException. (str "could not stop [" name "] due to") t)))))
     (alter-meta! var assoc :started? false)))
 
+;;TODO args might need more thinking
+(defn args [] @-args)
+
 (defn mount-state? [var]
   (= (-> var meta :mount-state)
      mount-state))
@@ -82,7 +86,7 @@
        doall))
 
 (defn start [& states]
-  (let [states (or states (find-all-states))]
+  (let [states (or (seq states) (find-all-states))]
     (bring states up <)
     :started))
 
@@ -90,3 +94,9 @@
   (let [states (or states (find-all-states))]
     (bring states down >)
     :stopped))
+
+(defn start-with-args [xs & states]
+  (reset! -args xs)
+  (if (first states)
+    (start states)
+    (start)))

test/app/app.clj

@@ -1,10 +1,12 @@
 (ns app
   (:require [datomic.api :as d]
             [clojure.tools.nrepl.server :refer [start-server stop-server]]
+            [clojure.tools.cli :refer [parse-opts]]
             [mount :refer [defstate]]
             [app.utils.datomic :refer [touch]]
             [app.config :refer [app-config]]
-            [app.nyse :as nyse]))
+            [app.nyse :as nyse])
+  (:gen-class))
 
 ;; example on creating a network REPL
 (defn- start-nrepl [{:keys [host port]}]
@@ -60,6 +62,15 @@
 (defn create-nyse-schema []
   (create-schema nyse/conn))
 
-;; example of an app entry point
+;; "any" regular function to pass arguments
+(defn parse-args [args]
+  (let [opts [["-d" "--datomic-uri [datomic url]" "Datomic URL"
+              :default "datomic:mem://mount"]
+              ["-h" "--help"]]]
+    (-> (parse-opts args opts)
+        :options)))
+
+;; example of an app entry point with arguments
 (defn -main [& args]
-  (mount/start))
+  (mount/start-with-args
+    (parse-args args)))

test/app/config.clj

@@ -5,6 +5,8 @@
 
 (defn load-config [path]
   (info "loading config from" path)
+  (if (:help (mount/args))
+    (info "\n\nthis is a sample mount app to demo how to pass and read runtime arguments\n"))
   (-> path 
       slurp 
       edn/read-string))

test/app/nyse.clj

@@ -4,18 +4,15 @@
             [clojure.tools.logging :refer [info]]
             [app.config :refer [app-config]]))
 
-(defn- new-connection [conf]
-  (info "conf: " conf)
-  (let [uri (get-in conf [:datomic :uri])]
-    (info "creating a connection to datomic:" uri)
-    (d/create-database uri)
-    (d/connect uri)))
+(defn- new-connection [{:keys [datomic-uri]}]
+  (info "creating a connection to datomic:" datomic-uri)
+  (d/create-database datomic-uri)
+  (d/connect datomic-uri))
 
-(defn disconnect [conf conn]
-  (let [uri (get-in conf [:datomic :uri])]
-    (info "disconnecting from " uri)
-    (.release conn)                        ;; usually it's not released, here just to illustrate the access to connection on (stop)
-    (d/delete-database uri)))
+(defn disconnect [{:keys [datomic-uri]} conn]
+  (info "disconnecting from " datomic-uri)
+  (.release conn)                        ;; usually it's not released, here just to illustrate the access to connection on (stop)
+  (d/delete-database datomic-uri))
 
-(defstate conn :start (new-connection app-config)
-               :stop (disconnect app-config conn))
+(defstate conn :start (new-connection (mount/args))
+               :stop (disconnect (mount/args) conn))