Heroku: buildpack for Clojure tools

Over the past 4 years I've had the fortune of working full time in Clojure. The backend for the Relish mobile app is built in Clojure. It runs on Heroku and we use lein as our build tool. This has been a great development experience. But, for the next Clojure project I wanted to try tools.deps and tools.build. Unfortunately, there isn't an official Heroku buildpack and none of the unofficial alternatives were quite what I was looking for. In the end I decided to roll my own to get comfortable with Heroku's build pack API.

To use this build pack

Set your heroku app to use this build pack:

heroku buildpacks:set https://github.com/andersmurphy/heroku-buildpack-clojure-tools.git -a my-app

Make sure your project root contains the following files:

A Procfile file:

web: java -jar target/my-app.jar -m my-app.app

A bin/build file (make this file executable with chmod +x bin/build):

clojure -T:build uber

A deps.edn file:

{:paths   ["src" "resources"]
 :deps    {org.clojure/clojure {:mvn/version "1.11.0-alpha3"}}
 :aliases {:build
           {:deps       {io.github.clojure/tools.build {:git/tag "v0.6.8"
                                                        :git/sha
                                                        "d79ae84"}}
            :ns-default build}}}

A build.clj file:

(ns build
  (:require [clojure.tools.build.api :as b]))

(def lib 'my-app)
(def class-dir "target/classes")
(def basis (b/create-basis {:project "deps.edn"}))
(def uber-file (format "target/%s.jar" (name lib)))

(defn clean [_] (b/delete {:path "target"}))

(defn uber
  [_]
  (clean nil)
  (b/copy-dir {:src-dirs ["src" "resources"] :target-dir class-dir})
  (b/compile-clj {:basis basis :src-dirs ["src"] :class-dir class-dir})
  (b/uber {:class-dir class-dir
           :uber-file uber-file
           :basis     basis
           :main      'my-app.app}))

For the full repo check out Heroku buildpack for clojure tools.