Add docker-setup hook

This allows the user to make any necessary configuration changes to
Docker before setting up any containers, allowing those configuration
changes to take effect from the outset.

lib/kamal/cli/main.rb

@@ -6,6 +6,8 @@ def setup
         say "Ensure Docker is installed...", :magenta
         invoke "kamal:cli:server:bootstrap"
 
+        run_hook "docker-setup"
+
         say "Push env files...", :magenta
         invoke "kamal:cli:env:push"
 

lib/kamal/cli/templates/sample_hooks/docker-setup.sample

@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+
+# A sample docker-setup hook
+#
+# Sets up a Docker network which can then be used by the application’s containers
+
+ssh user@example.com docker network create kamal

test/cli/main_test.rb

@@ -2,12 +2,17 @@
 
 class CliMainTest < CliTestCase
   test "setup" do
+    invoke_options = { "config_file" => "test/fixtures/deploy_simple.yml", "version" => "999", "skip_hooks" => false }
+
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:server:bootstrap")
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:env:push")
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:accessory:boot", [ "all" ])
     Kamal::Cli::Main.any_instance.expects(:deploy)
+    hook_variables = { version: 999, service_version: "app@999", hosts: "1.1.1.1,1.1.1.2", command: "setup" }
 
-    run_command("setup")
+    run_command("setup").tap do |output|
+      assert_hook_ran "docker-setup", output, **hook_variables
+    end
   end
 
   test "deploy" do

test/integration/docker/deployer/app/.kamal/hooks/docker-setup

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo "Docker set up!"
+mkdir -p /tmp/${TEST_ID} && touch /tmp/${TEST_ID}/docker-setup