Make it possible to force an exact version from package.json

lib/capistrano-node.rb

@@ -29,14 +29,24 @@ def choose_version(requirement, versions = [])
       end
     end
 
-    # Internal: Parse requirement from package.json
+    # Internal: Parse requirement from `file`
     #
     # file - package.json file object
     #
     # Returns Gem::Requirement
     def requirement(file)
-      json = JSON.parse(File.open('package.json', 'r:utf-8').read)
-      Gem::Requirement.create(json['engines']['node'])
+      Gem::Requirement.create(raw_requirement(file))
+    end
+
+    def exact_requirement(file)
+      requirement = raw_requirement(file)
+      raise "No exact node version specified" unless Gem::Requirement.create(requirement).exact?
+      requirement
+    end
+
+    def raw_requirement(file)
+      json = JSON.parse(File.open(file, 'r:utf-8').read)
+      json['engines']['node'].strip
     end
   end
 end

lib/capistrano/node.rb

@@ -27,6 +27,7 @@ def remote_versions(path, prefix)
   set :node_dir, '/opt/nodejs/versions' unless defined? node_dir # Node versions dir
   set :version_prefix, 'v' unless defined? version_prefix # Prefix for versin dirs, (v0.6.10 -> 'v')
   set :npm_flags, '--production --quiet' unless defined? npm_flags
+  set :force_node_version, false unless defined? force_node_version
 
   # Lazy variable to list available node versions from either local or remote
   set :available_node_versions do
@@ -39,8 +40,12 @@ def remote_versions(path, prefix)
 
   # Export used Node version from package.json
   set :node_version do
-    requirement = Capistrano::Node.requirement 'package.json'
-    Capistrano::Node.choose_version requirement, available_node_versions
+    if force_node_version
+      Capistrano::Node.exact_requirement 'package.json'
+    else
+      requirement = Capistrano::Node.requirement 'package.json'
+      Capistrano::Node.choose_version requirement, available_node_versions
+    end
   end
 
   set :node_version_dir, "#{node_dir}/#{version_prefix}#{node_version}/bin"