Merge pull request #879 from basecamp/seed-mirror

Seed docker mirrors by pulling once per mirror first

lib/kamal/cli/build.rb

@@ -59,11 +59,14 @@ class Kamal::Cli::Build < Kamal::Cli::Base
 
   desc "pull", "Pull app image from registry onto servers"
   def pull
-    on(KAMAL.hosts) do
-      execute *KAMAL.auditor.record("Pulled image with version #{KAMAL.config.version}"), verbosity: :debug
-      execute *KAMAL.builder.clean, raise_on_non_zero_exit: false
-      execute *KAMAL.builder.pull
-      execute *KAMAL.builder.validate_image
+    if (first_hosts = mirror_hosts).any?
+      #  Pull on a single host per mirror first to seed them
+      say "Pulling image on #{first_hosts.join(", ")} to seed the #{"mirror".pluralize(first_hosts.count)}...", :magenta
+      pull_on_hosts(first_hosts)
+      say "Pulling image on remaining hosts...", :magenta
+      pull_on_hosts(KAMAL.hosts - first_hosts)
+    else
+      pull_on_hosts(KAMAL.hosts)
     end
   end
 
@@ -131,4 +134,28 @@ class Kamal::Cli::Build < Kamal::Cli::Base
         end
       end
     end
+
+    def mirror_hosts
+      if KAMAL.hosts.many?
+        mirror_hosts = Concurrent::Hash.new
+        on(KAMAL.hosts) do |host|
+          first_mirror = capture_with_info(*KAMAL.builder.first_mirror).strip.presence
+          mirror_hosts[first_mirror] ||= host if first_mirror
+        rescue SSHKit::Command::Failed => e
+          raise unless e.message =~ /error calling index: reflect: slice index out of range/
+        end
+        mirror_hosts.values
+      else
+        []
+      end
+    end
+
+    def pull_on_hosts(hosts)
+      on(hosts) do
+        execute *KAMAL.auditor.record("Pulled image with version #{KAMAL.config.version}"), verbosity: :debug
+        execute *KAMAL.builder.clean, raise_on_non_zero_exit: false
+        execute *KAMAL.builder.pull
+        execute *KAMAL.builder.validate_image
+      end
+    end
 end

lib/kamal/commands/builder.rb

@@ -2,7 +2,7 @@ require "active_support/core_ext/string/filters"
 
 class Kamal::Commands::Builder < Kamal::Commands::Base
   delegate :create, :remove, :push, :clean, :pull, :info, :context_hosts, :config_context_hosts, :validate_image,
-    to: :target
+           :first_mirror, to: :target
 
   include Clone
 

lib/kamal/commands/builder/base.rb

@@ -40,6 +40,10 @@ class Kamal::Commands::Builder::Base < Kamal::Commands::Base
     []
   end
 
+  def first_mirror
+    docker(:info, "--format '{{index .RegistryConfig.Mirrors 0}}'")
+  end
+
   private
     def build_tags
       [ "-t", config.absolute_image, "-t", config.latest_image ]

test/cli/build_test.rb

@@ -169,12 +169,41 @@ class CliBuildTest < CliTestCase
 
   test "pull" do
     run_command("pull").tap do |output|
+      assert_match /docker info --format '{{index .RegistryConfig.Mirrors 0}}'/, output
       assert_match /docker image rm --force dhh\/app:999/, output
       assert_match /docker pull dhh\/app:999/, output
       assert_match "docker inspect -f '{{ .Config.Labels.service }}' dhh/app:999 | grep -x app || (echo \"Image dhh/app:999 is missing the 'service' label\" && exit 1)", output
     end
   end
 
+  test "pull with mirror" do
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :info, "--format '{{index .RegistryConfig.Mirrors 0}}'")
+      .returns("registry-mirror.example.com")
+      .at_least_once
+
+    run_command("pull").tap do |output|
+      assert_match /Pulling image on 1\.1\.1\.\d to seed the mirror\.\.\./, output
+      assert_match "Pulling image on remaining hosts...", output
+      assert_match /docker pull dhh\/app:999/, output
+      assert_match "docker inspect -f '{{ .Config.Labels.service }}' dhh/app:999 | grep -x app || (echo \"Image dhh/app:999 is missing the 'service' label\" && exit 1)", output
+    end
+  end
+
+  test "pull with mirrors" do
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :info, "--format '{{index .RegistryConfig.Mirrors 0}}'")
+      .returns("registry-mirror.example.com", "registry-mirror2.example.com")
+      .at_least_once
+
+    run_command("pull").tap do |output|
+      assert_match /Pulling image on 1\.1\.1\.\d, 1\.1\.1\.\d to seed the mirrors\.\.\./, output
+      assert_match "Pulling image on remaining hosts...", output
+      assert_match /docker pull dhh\/app:999/, output
+      assert_match "docker inspect -f '{{ .Config.Labels.service }}' dhh/app:999 | grep -x app || (echo \"Image dhh/app:999 is missing the 'service' label\" && exit 1)", output
+    end
+  end
+
   test "create" do
     run_command("create").tap do |output|
       assert_match /docker buildx create --use --name kamal-app-multiarch/, output

test/cli/main_test.rb

@@ -122,6 +122,11 @@ class CliMainTest < CliTestCase
       .with(:docker, :buildx, :inspect, "kamal-app-multiarch", "> /dev/null")
       .returns("")
 
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :info, "--format '{{index .RegistryConfig.Mirrors 0}}'")
+      .returns("")
+      .at_least_once
+
     assert_raises(Kamal::Cli::LockError) do
       run_command("deploy")
     end
@@ -155,6 +160,11 @@ class CliMainTest < CliTestCase
       .with(:docker, :buildx, :inspect, "kamal-app-multiarch", "> /dev/null")
       .returns("")
 
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :info, "--format '{{index .RegistryConfig.Mirrors 0}}'")
+      .returns("")
+      .at_least_once
+
     assert_raises(SSHKit::Runner::ExecuteError) do
       run_command("deploy")
     end

test/commands/builder_test.rb

@@ -200,6 +200,11 @@ class CommandsBuilderTest < ActiveSupport::TestCase
     assert_equal [ "unix:///var/run/docker.sock", "ssh://host" ], command.config_context_hosts
   end
 
+  test "mirror count" do
+    command = new_builder_command
+    assert_equal "docker info --format '{{index .RegistryConfig.Mirrors 0}}'", command.first_mirror.join(" ")
+  end
+
   private
     def new_builder_command(additional_config = {})
       Kamal::Commands::Builder.new(Kamal::Configuration.new(@config.merge(additional_config), version: "123"))