diff --git a/.gitignore b/.gitignore
index 0bb75ea..f7ad223 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 /bin/
 /.shards/
 *.dwarf
+tmp/
diff --git a/examples/hello_cr/funko.yml b/examples/hello_cr/funko.yml
new file mode 100644
index 0000000..44354bb
--- /dev/null
+++ b/examples/hello_cr/funko.yml
@@ -0,0 +1,2 @@
+name: hello
+runtime: crystal
diff --git a/templates/crystal/Dockerfile b/runtimes/crystal/Dockerfile
similarity index 100%
rename from templates/crystal/Dockerfile
rename to runtimes/crystal/Dockerfile
diff --git a/templates/crystal/main.cr b/runtimes/crystal/main.cr
similarity index 100%
rename from templates/crystal/main.cr
rename to runtimes/crystal/main.cr
diff --git a/templates/crystal/shard.yml b/runtimes/crystal/shard.yml
similarity index 100%
rename from templates/crystal/shard.yml
rename to runtimes/crystal/shard.yml
diff --git a/shard.lock b/shard.lock
index 045111e..3e68c9c 100644
--- a/shard.lock
+++ b/shard.lock
@@ -9,6 +9,6 @@ shards:
     version: 0.4.0
 
   docr:
-    git: https://github.com/marghidanu/docr.git
-    version: 0.1.1+git.commit.59fb466b748d5d29a8f2de88a54b71dbfe0285aa
+    git: https://github.com/ralsina/docr.git
+    version: 0.1.1+git.commit.18f15cc7111b1d0c63347c7cca07aee9ec87a7a8
 
diff --git a/shard.yml b/shard.yml
index e273562..f426b0b 100644
--- a/shard.yml
+++ b/shard.yml
@@ -16,5 +16,6 @@ license: MIT
 dependencies:
   docr:
     github: ralsina/docr
+    branch: add_exposed_ports
   commander:
     github: mrrooijen/commander
diff --git a/src/faaso.cr b/src/faaso.cr
index bdd1987..cb3c5b9 100644
--- a/src/faaso.cr
+++ b/src/faaso.cr
@@ -3,6 +3,7 @@ require "docr"
 require "docr/utils.cr"
 require "file_utils"
 require "uuid"
+require "./funko.cr"
 
 # TODO: Write documentation for `Faaso`
 module Faaso
@@ -19,22 +20,46 @@ module Faaso
       end
 
       def run
-        @arguments.each do |arg|
-          # A function is a folder with stuff in it
-          # TODO: decide template based on file extensions or other metadata
-          template = "templates/crystal"
-          tmp_dir = "tmp/#{UUID.random}"
-          slug = arg.gsub("/", "_").strip("_")
-          repo = "localhost:5000"
-          tag = "#{repo}/#{slug}:latest"
-          puts "Building function... #{arg} in #{tmp_dir}"
-          Dir.mkdir_p("tmp") unless File.exists? "tmp"
-          FileUtils.cp_r(template, tmp_dir)
-          Dir.glob(arg + "/**/*").each do |file|
-            FileUtils.cp(file, tmp_dir)
+        funkos = Funko.from_paths(@arguments)
+        funkos.each do |funko|
+          # Create temporary build location
+          tmp_dir = Path.new("tmp", UUID.random.to_s)
+          Dir.mkdir_p(tmp_dir) unless File.exists? tmp_dir
+
+          # Copy runtime if requested
+          if !funko.runtime.nil?
+            runtime_dir = Path.new("runtimes", funko.runtime.to_s)
+            if !File.exists? runtime_dir
+              puts "Error: runtime #{funko.runtime} not found"
+              next
+            end
+            Dir.glob("#{runtime_dir}/*").each { |src|
+              FileUtils.cp_r(src, tmp_dir)
+            }
           end
+
+          # Copy funko
+          if funko.path.empty?
+            puts "Internal error: empty funko path for #{funko.name}"
+            next
+          end
+          Dir.glob("#{funko.path}/*").each { |src|
+            FileUtils.cp_r(src, tmp_dir)
+          }
+
+          puts "Building function... #{funko.name} in #{tmp_dir}"
+
+          slug = funko.name
+
+          # FIXME: this should be configurable
+          repo = "localhost:5000"
+          tag = "#{repo}/#{funko.name}:latest"
+
           docker_api = Docr::API.new(Docr::Client.new)
-          docker_api.images.build(context: tmp_dir, tags: [tag, "#{slug}:latest"]) { }
+          docker_api.images.build(
+            context: tmp_dir.to_s,
+            tags: [tag, "#{funko.name}:latest"]) { }
+
           puts "Pushing to repo as #{tag}"
           docker_api.images.tag(repo: repo, name: slug, tag: "latest")
           # FIXME: pushing is broken because my test registry has no auth
diff --git a/src/funko.cr b/src/funko.cr
new file mode 100644
index 0000000..bcbbb19
--- /dev/null
+++ b/src/funko.cr
@@ -0,0 +1,38 @@
+require "yaml"
+
+class Funko
+  include YAML::Serializable
+
+  # Required, the name of the funko. Must be unique across FaaSO
+  property name : String
+
+  # if Nil, it has no template whatsoever
+  property runtime : (String | Nil)? = nil
+
+  # Port of the funko process (optional, default is 3000)
+  property port : UInt32? = 3000
+
+  # Extra packages, passed as EXTRA_PACKAGES argument
+  # to the Dockerfile, use it for installing things in
+  # the SHIPPED docker image
+  property extra_packages : Array(String)?
+
+  # Extra packages, passed as DEVEL_PACKAGES argument
+  # to the Dockerfile, use it for installing things in
+  # the docker stage used to build the code
+  property devel_packages : Array(String)?
+
+  # Where this is located in the filesystem
+  @[YAML::Field(ignore: true)]
+  property path : String = ""
+
+  def self.from_paths(paths : Array(String | Path)) : Array(Funko)
+    paths.map { |path| Path.new(path, "funko.yml") }
+      .select { |path| File.exists?(path) }
+      .map { |path|
+        f = Funko.from_yaml(File.read(path.to_s))
+        f.path = path.parent.to_s
+        f
+      }
+  end
+end