new supported env vars RAILS_DEV_BOX_(RAM|CPUS)

Author: fxn

README.md

@@ -33,6 +33,14 @@ Port 3000 in the host computer is forwarded to port 3000 in the virtual machine.
 
     bin/rails server -b 0.0.0.0
 
+## RAM and CPUs
+
+By default, the VM launches with 2 GB of RAM and 2 CPUs.
+
+These can be overridden by setting the environment variables `RAILS_DEV_BOX_RAM` and `RAILS_DEV_BOX_CPUS`, respectively. Settings on VM creation don't matter, the environment variables are checked each time the VM boots.
+
+`RAILS_DEV_BOX_RAM` has to be expressed in megabytes, so configure 4096 if you want the VM to have 4 GB of RAM.
+
 ## What's In The Box
 
 * Development tools

Vagrantfile

@@ -11,7 +11,7 @@ Vagrant.configure('2') do |config|
   config.vm.provision :shell, path: 'bootstrap.sh', keep_color: true
 
   config.vm.provider 'virtualbox' do |v|
-    v.memory = 2048
-    v.cpus = 2
+    v.memory = ENV.fetch('RAILS_DEV_BOX_RAM', 2048).to_i
+    v.cpus   = ENV.fetch('RAILS_DEV_BOX_CPUS', 2).to_i
   end
 end