Skip setting the proxy flag when ssl is false

Fixes: https://github.com/basecamp/kamal/issues/1037

lib/kamal/configuration/proxy.rb

@@ -29,7 +29,7 @@ class Kamal::Configuration::Proxy
   def deploy_options
     {
       host: hosts,
-      tls: proxy_config["ssl"],
+      tls: proxy_config["ssl"].presence,
       "deploy-timeout": seconds_duration(config.deploy_timeout),
       "drain-timeout": seconds_duration(config.drain_timeout),
       "health-check-interval": seconds_duration(proxy_config.dig("healthcheck", "interval")),

test/commands/app_test.rb

@@ -135,6 +135,14 @@ class CommandsAppTest < ActiveSupport::TestCase
       new_command.deploy(target: "172.1.0.2").join(" ")
   end
 
+  test "deploy with SSL false" do
+    @config[:proxy] = { "ssl" => false }
+
+    assert_equal \
+      "docker exec kamal-proxy kamal-proxy deploy app-web --target=\"172.1.0.2:80\" --deploy-timeout=\"30s\" --drain-timeout=\"30s\" --buffer-requests --buffer-responses --log-request-header=\"Cache-Control\" --log-request-header=\"Last-Modified\" --log-request-header=\"User-Agent\"",
+      new_command.deploy(target: "172.1.0.2").join(" ")
+  end
+
   test "remove" do
     assert_equal \
       "docker exec kamal-proxy kamal-proxy remove app-web",