support --pull flag on cook to automatically pull the base image

lib/fpm/fry/client.rb

@@ -183,7 +183,24 @@ def changes(name)
   end
 
   def pull(image)
-    agent.post(path: url('images','create'), query: {'fromImage' => image})
+    last_status = ""
+    streamer = lambda do |chunk, remaining_bytes, total_bytes|
+      chunk.each_line do |line|
+        begin
+          msg = JSON.parse(line)
+          status, progress, id = *msg.values_at("status", "progress", "id")
+          id += ": " if id
+          status += " " if progress
+          move_up_one_line = $stdout.tty? && status =~ /Downloading|Extracting/ && last_status =~ /Downloading|Extracting/
+          last_status = status
+          cursor_move = move_up_one_line ? "\e[1A" : ""
+          puts [cursor_move, id, status, progress].join("")
+        rescue JSON::ParserError => e
+          $stderr.puts "Could not parse JSON response from docker: #{e}"
+        end
+      end
+    end
+    agent.post(path: url('images','create'), query: {'fromImage' => image}, :response_block => streamer)
   end
 
   def create(image)

lib/fpm/fry/command/cook.rb

@@ -4,8 +4,9 @@ class Command::Cook < Command
 
     option '--keep', :flag, 'Keep the container after build'
     option '--overwrite', :flag, 'Overwrite package', default: true
-    option '--verbose', :fag, 'Verbose output', default: false
+    option '--verbose', :flag, 'Verbose output', default: false
     option '--platform', 'PLATFORM', default: nil
+    option '--pull', :flag, 'Pull base image', default: false
 
     UPDATE_VALUES = ['auto','never','always']
     option '--update',"<#{UPDATE_VALUES.join('|')}>", 'Update image before installing packages ( only apt currently )', attribute_name: 'update', default: 'auto' do |value|
@@ -203,6 +204,13 @@ def update?
       end
     end
 
+    def pull_base_image!
+      client.pull(image)
+    rescue Excon::Error
+      logger.error "could not pull base image #{image}"
+      raise
+    end
+
     def build!
       body = begin
               url = client.url('containers','create')
@@ -407,6 +415,8 @@ def adjust_config_files( output )
   public
 
     def execute
+      pull_base_image! if pull?
+
       # force some eager loading
       lint_recipe_file!
       builder

spec/client_spec.rb

@@ -14,6 +14,17 @@
       to_return(:status => 200, :body =>'{"ApiVersion":"1.9"}', :headers => {})
   end
 
+  describe '#pull' do
+    it 'pulls an existing image' do
+      client = real_docker
+      res = nil
+      expect{
+        res = client.pull("ubuntu:jammy")
+      }.to output(/Status: Downloaded newer image for ubuntu:jammy/).to_stdout
+      expect(res.status).to eq(200)
+    end
+  end
+
   describe '#read' do
     context 'existing file' do
       let(:body){