Dont build image if it has already been pushed

lib/kamal/cli/build.rb

@@ -5,7 +5,7 @@ class BuildError < StandardError; end
 
   desc "deliver", "Build app and push app image to registry then pull image on servers"
   def deliver
-    push
+    push unless already_built?
     pull
   end
 
@@ -158,4 +158,10 @@ def pull_on_hosts(hosts)
         execute *KAMAL.builder.validate_image
       end
     end
+
+    def already_built?
+      run_locally { execute *KAMAL.docker.manifest(KAMAL.builder.absolute_image) }
+    rescue SSHKit::Command::Failed
+      false
+    end
 end

lib/kamal/commands/builder.rb

@@ -3,6 +3,7 @@
 class Kamal::Commands::Builder < Kamal::Commands::Base
   delegate :create, :remove, :push, :clean, :pull, :info, :context_hosts, :config_context_hosts, :validate_image,
            :first_mirror, to: :target
+  delegate :absolute_image, to: :config
 
   include Clone
 

lib/kamal/commands/docker.rb

@@ -14,6 +14,10 @@ def running?
     docker :version
   end
 
+  def manifest(tag)
+    docker :manifest, :inspect, tag
+  end
+
   # Do we have superuser access to install Docker and start system services?
   def superuser?
     [ '[ "${EUID:-$(id -u)}" -eq 0 ] || command -v sudo >/dev/null || command -v su >/dev/null' ]