Boot and Vagrant

Boot is a new-ish software build system designed for and built with Clojure and ClojureScript. Here are some notes on using it with a Vagrant session on a Mac.¹

This is very much a work in progress. I generally like working with Vagrant to keep my development environments packaged, isolated, and repeatably built. No exception while I learn Clojure / ClojureScript, and as I decide on the surrounding tooling like boot. The main hurdles were to get the REPL and reload connections to be exposed to Vagrant network forwards.

build.boot

;; define dev task as composition of subtasks
(deftask dev
  "Launch Immediate Feedback Development Environment"
  []
  (comp 
   (serve :dir "target")
   (watch)
   (reload :port (int 3001))            ;; ports 3000-3003 are forwarded by Vagrantfile
   (cljs-repl :nrepl-opts {:port 3002 :bind "0.0.0.0"})
   (cljs)
   (target :dir #{"target"})))

1. :port in reload needs to be cast to an int.
2. I failed to get bash to pass the EDN parameter {:port 3002 :bind "0.0.0.0"} to cljs-repl for the nREPL port on the command line, so creating a deftask is necessary.²
3. The :bind parameter in cljs-repl overrides the default localhost, which is not visible to Vagrant.
4. Run with boot dev.
5. Thank you to modern_cljs tutorial for the source task.

Vagrantfile

  config.vm.network "forwarded_port", guest: 3000, host: 3000 # web server
  config.vm.network "forwarded_port", guest: 3001, host: 3001 # reload browser signaling
  config.vm.network "forwarded_port", guest: 3002, host: 3002 # nREPL 
  config.vm.network "forwarded_port", guest: 3003, host: 3003 # bREPL 

Emacs

To connect to the guest nREPL for the CLJS environment

M-x cider-connect
localhost
3002

1. M-x cider-connect doesn’t (yet) bind the host cider environment to the guest REPL, so sadly a lot of the magic isn’t working yet, like cider-eval-defun-at-point

In the nREPL, to connect to the bREPL

boot.user> (start-repl :port (int 3003) :ip "0.0.0.0")
<< started Weasel server on ws://0.0.0.0:3003 >>
<< waiting for client to connect ... Connection is ws://localhost:3003
Writing boot_cljs_repl.cljs...
(open host browser at http://localhost:3000)
 connected! >>
To quit, type: :cljs/quit
nil
cljs.user> (js/alert "hello")
(dismiss popup in host browser)

Detailed use case

• a Clojure application server in development mode on port 3000
• the guest virtual machine is running Ubuntu Linux.
• web application runs ClojureScript
• web browser is on host Mac
• Emacs running Cider is the development environment running on the host Mac
• Cider to nREPL on guest, chained to bREPL to the browser for debugging / inspection.
• Boot tasks: serve watch³ reload cljs-repl cljs
• Guest OS: Ubuntu Trusty64. Host OS: MacOS 10.11.5. Vagrant version: 1.8.1. Provider: vm_fusion. Hypervisor: VMware Fusion 8.1.1. Clojure: 1.7.0. Java: SE Runtime build 1.8.0_91-b14 and HotSpot 64-bit Server VM build 25.91-b14, mixed mode. Emacs: Aquamacs 3.2 GNU Emacs 24.4.51.2