deploy compojure app that is also a CLI app

I have a Clojure app that I can use both from the command-line, and as a Compojure app. I did that by putting a ring handler and a main function (clojure.tools.cli) in my leiningen project.clj.

{... :main my-app.core :ring {:handler my-app.handler/handler }}

The handler is defined (defroutes handler ...).

Now if I want to run the CLI app, I can run lein uberjar and then java -jar arguments. And I can also run the Compojure app via lein ring server PORT.

Now, how do I deploy the thing as a Compojure app (and not a CLI app) in a production server ? (Bonus points for explaining how lein ring server works.)

Note : I already use nginx if that can help, and I'm flexible on the container to be used.

Solution

Here's kind of the default template I use for new projects. It allows you to do dependency injection into ring apps and run the app from the command line as an uberjar. You can read more here: http://www.sparxeng.com/blog/software/improved-clojure-workflow

; handler.clj    
(defn wrap-inject-deps
  "Ring middleware that injects the dependencies into each ring request map"
  [handler deps]
  (fn [req]
    (handler (assoc req :deps deps))))

(defn create-handler
  "Similar to the default ring 'handler', but with a parameter to let you inject dependencies"
  [deps]
  (-> (routes
        api-routes
        web-routes
        (route/resources "/"))
      (kwp/wrap-keyword-params)
      (params/wrap-params)
      (json/wrap-json-params)
      (json/wrap-json-response)
      (wrap-inject-deps deps))) ; this injects dependencies

(defn start-jetty
  "Launch the Jetty instance"
  [deps]
  (let [port (Integer. (or (-> system :env :port) 5000))
        handler (create-handler deps)]
    (jetty/run-jetty handler {:port port :join? false})))


; system.clj
(defn get-env
  "Initialize configuration vars"
  []
  {:aws-access-key-id     (System/getenv "AWS_ACCESS_KEY_ID")
   :aws-secret-access-key (System/getenv "AWS_SECRET_ACCESS_KEY")
   :mongo-url             (System/getenv "MONGO_URL"))

(defn start
  "Launch dependencies such as DB connection and Jetty. Return these as a map, for use in REPL"
  [& [env]]
  (let [env (or env (get-env))
        deps {:env     env
              :monger  (db/init env)}
        jetty (handler/start-jetty deps)]
    (assoc deps :jetty jetty)))


; program.clj
(defn -main [& [port]]
  "App entrypoint"
  (let [env (system/get-env) ; "env" is just a map of config variables, that can be hard-coded, read from file, or whatever you want.
        env (if port (assoc env :port port) env)]
    (system/start env)))

You can then use leiningen profiles if you need to create multiple apps with different entrypoints from your codebase.