diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3d21e370..f166385c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,6 +27,7 @@ jobs:
           - "4.0"
           - "3.4"
           - "3.3"
+          - "jruby"
         rack:
           - "~> 2.0"
           - "~> 3.0"
@@ -34,12 +35,6 @@ jobs:
           - ruby: "4.0"
             rack: "~> 2.0"
             coverage: "true"
-          - ruby: "jruby"
-            rack: "~> 2.0"
-            optional: true
-          - ruby: "jruby"
-            rack: "~> 3.0"
-            optional: true
     env:
       COVERAGE: ${{ matrix.coverage }}
       RACK_MATRIX_VALUE: ${{ matrix.rack || '' }}
diff --git a/Gemfile b/Gemfile
index 7d05977d..2143d36f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -49,7 +49,6 @@ gem "hanami-devtools", github: "hanami/devtools", branch: "main"
 
 group :test do
   gem "pry"
-  gem "readline"
   gem "rspec", "~> 3.9"
   gem "ostruct", require: false
 end
diff --git a/lib/hanami/cli/commands/app/db/utils/database.rb b/lib/hanami/cli/commands/app/db/utils/database.rb
index 7360a72a..bd4ed336 100644
--- a/lib/hanami/cli/commands/app/db/utils/database.rb
+++ b/lib/hanami/cli/commands/app/db/utils/database.rb
@@ -38,6 +38,10 @@ def sql
                   require_relative("postgres")
                   Postgres
                 },
+                "mysql" => -> {
+                  require_relative("mysql")
+                  Mysql
+                },
                 "mysql2" => -> {
                   require_relative("mysql")
                   Mysql
@@ -45,10 +49,7 @@ def sql
               ).freeze
 
               def self.database_class(database_url)
-                database_scheme = URI(database_url).scheme
-                if database_scheme == "jdbc"
-                  database_scheme = URI(database_url.sub("jdbc:", "")).scheme
-                end
+                database_scheme = URI(database_url.delete_prefix("jdbc:")).scheme
                 DATABASE_CLASS_RESOLVER[database_scheme].call
               end
 
@@ -86,8 +87,20 @@ def database_url
                 slice.container.providers[:db].source.database_urls.fetch(gateway_name)
               end
 
+              # JDBC URLs (required to connect via JRuby) nest the real URL after "jdbc:", e.g.
+              # "jdbc:postgresql://localhost/app", so parse that nested URL instead.
               def database_uri
-                @database_uri ||= URI(database_url)
+                @database_uri ||= URI(database_url.delete_prefix("jdbc:"))
+              end
+
+              # JDBC drivers expect the user and password as query params, e.g.
+              # "jdbc:postgresql://localhost/app?user=postgres&password=secret".
+              def database_user
+                database_uri.user || database_query_params["user"]
+              end
+
+              def database_password
+                database_uri.password || database_query_params["password"]
               end
 
               def gateway
@@ -197,10 +210,8 @@ def schema_migrations_sql_dump
 
               private
 
-              def database_path
-                database_uri.path ||
-                  # For `jdbc:` URIs the path is exposed via the opaque component
-                  database_uri.opaque.sub(%r{^\w+:/?}, "")
+              def database_query_params
+                @database_query_params ||= URI.decode_www_form(database_uri.query.to_s).to_h
               end
 
               def jruby?
diff --git a/lib/hanami/cli/commands/app/db/utils/mysql.rb b/lib/hanami/cli/commands/app/db/utils/mysql.rb
index f14d943e..b15ddac2 100644
--- a/lib/hanami/cli/commands/app/db/utils/mysql.rb
+++ b/lib/hanami/cli/commands/app/db/utils/mysql.rb
@@ -71,13 +71,13 @@ def cli_options
                 [].tap { |opts|
                   opts << "--host=#{Shellwords.escape(database_uri.host)}" if database_uri.host
                   opts << "--port=#{Shellwords.escape(database_uri.port)}" if database_uri.port
-                  opts << "--user=#{Shellwords.escape(database_uri.user)}" if database_uri.user
+                  opts << "--user=#{Shellwords.escape(database_user)}" if database_user
                 }.join(" ")
               end
 
               def cli_env_vars
                 @cli_env_vars ||= {}.tap do |vars|
-                  vars["MYSQL_PWD"] = database_uri.password.to_s if database_uri.password
+                  vars["MYSQL_PWD"] = database_password.to_s if database_password
                 end
               end
             end
diff --git a/lib/hanami/cli/commands/app/db/utils/postgres.rb b/lib/hanami/cli/commands/app/db/utils/postgres.rb
index f65a2068..9e18ecd1 100644
--- a/lib/hanami/cli/commands/app/db/utils/postgres.rb
+++ b/lib/hanami/cli/commands/app/db/utils/postgres.rb
@@ -87,10 +87,12 @@ def escaped_name
               end
 
               def cli_env_vars
-                @cli_env_vars ||= %i[host port user password].each_with_object({}) do |field, vars|
-                  value = database_uri.public_send(field).to_s
-                  vars["PG#{field}".upcase] = value unless value.empty?
-                end
+                @cli_env_vars ||= {
+                  "PGHOST" => database_uri.host,
+                  "PGPORT" => database_uri.port,
+                  "PGUSER" => database_user,
+                  "PGPASSWORD" => database_password
+                }.transform_values(&:to_s).reject { |_, value| value.empty? }
               end
             end
           end
diff --git a/lib/hanami/cli/commands/app/db/utils/sqlite.rb b/lib/hanami/cli/commands/app/db/utils/sqlite.rb
index 74e01f65..459828fc 100644
--- a/lib/hanami/cli/commands/app/db/utils/sqlite.rb
+++ b/lib/hanami/cli/commands/app/db/utils/sqlite.rb
@@ -72,7 +72,7 @@ def name
                 @name ||=
                   begin
                     raw =
-                      if database_uri.scheme == "jdbc"
+                      if database_url.start_with?("jdbc:")
                         # For JDBC SQLite URIs like "jdbc:sqlite:db/app.sqlite3",
                         # we need to extract the path part after "jdbc:sqlite:"
                         # The standard URI.parse doesn't handle JDBC URIs well, so we remove the prefix manually
diff --git a/repo-sync.yml b/repo-sync.yml
index c4c4a859..a5e462b5 100644
--- a/repo-sync.yml
+++ b/repo-sync.yml
@@ -6,7 +6,6 @@ github_org: hanami
 ci:
   matrix:
     rack: ["~> 2.0", "~> 3.0"]
-  jruby: false
 gemspec:
   authors: ["Hanakai team"]
   email: ["info@hanakai.org"]
diff --git a/spec/integration/hanami/cli/commands/app/server_spec.rb b/spec/integration/hanami/cli/commands/app/server_spec.rb
index d2b3ce1d..03d97717 100644
--- a/spec/integration/hanami/cli/commands/app/server_spec.rb
+++ b/spec/integration/hanami/cli/commands/app/server_spec.rb
@@ -5,32 +5,30 @@
 require "puma"
 
 RSpec.describe Hanami::CLI::Commands::App::Server do
-  subject { described_class.new }
-
   it "starts rack server in the given environment" do
     host = ENV.fetch("HANAMI_CLI_TEST_HOST", "0.0.0.0")
     port = ENV.fetch("HANAMI_CLI_TEST_PORT", "2300")
+    app_root = File.join(__dir__, "../../../../../fixtures/test")
     begin
-      pid = fork do
-        $stdout.reopen "/dev/null", "a"
-        $stderr.reopen "/dev/null", "a"
-        subject.call(
-          config: File.join(File.dirname(__FILE__), "../../../../../fixtures/test/config.ru"),
-          host: host,
-          port: port,
-          env: "staging"
-        )
-      end
+      # Spawn a new process rather than forking, since fork is not available on JRuby
+      pid = Process.spawn(
+        "bin/hanami", "server", "--host=#{host}", "--port=#{port}", "--env=staging",
+        chdir: app_root, out: File::NULL, err: File::NULL
+      )
 
       response = open_uri("http://#{host}:#{port}/")
 
       expect(response).to eq("Hello, world! (staging)")
     ensure
-      Process.kill(:KILL, pid)
+      if pid
+        Process.kill(:KILL, pid)
+        Process.wait(pid)
+      end
     end
   end
 
-  def open_uri(uri, attempts = 5)
+  # Allow time for the new process to boot (including on JRuby)
+  def open_uri(uri, attempts = 30)
     URI.open(uri).read # rubocop:disable Security/Open
   rescue Errno::ECONNREFUSED
     raise if attempts.zero?
diff --git a/spec/support/helpers.rb b/spec/support/helpers.rb
index c35d6a2e..4aeb6d23 100644
--- a/spec/support/helpers.rb
+++ b/spec/support/helpers.rb
@@ -27,6 +27,23 @@ def sqlite_db_name(url, dir: nil)
         jruby? && dir ? File.join(dir, url) : url
       end
 
+      def postgres_url(db_suffix)
+        url = "#{POSTGRES_BASE_URL}#{db_suffix}"
+        jruby? ? jdbc_url(url, scheme: "postgresql") : url
+      end
+
+      def mysql_url(db_suffix)
+        url = "#{MYSQL_BASE_URL}#{db_suffix}"
+        jruby? ? jdbc_url(url, scheme: "mysql") : url
+      end
+
+      def jdbc_url(url, scheme:)
+        uri = URI(url)
+        # JDBC drivers expect the user and password as query params, not in the userinfo
+        query = URI.encode_www_form({user: uri.user, password: uri.password}.compact)
+        "jdbc:#{scheme}://#{uri.host}:#{uri.port}#{uri.path}?#{query}"
+      end
+
       def jruby?
         RUBY_ENGINE == "jruby"
       end
diff --git a/spec/unit/hanami/cli/commands/app/db/create_spec.rb b/spec/unit/hanami/cli/commands/app/db/create_spec.rb
index 25526cb9..6cd465bd 100644
--- a/spec/unit/hanami/cli/commands/app/db/create_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/create_spec.rb
@@ -76,7 +76,7 @@ def before_prepare
 
     describe "postgres", :postgres do
       before do
-        ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
+        ENV["DATABASE_URL"] = postgres_url("_app")
       end
 
       it "creates the database" do
@@ -101,7 +101,7 @@ def before_prepare
 
     describe "mysql", :mysql do
       before do
-        ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
+        ENV["DATABASE_URL"] = mysql_url("_app")
       end
 
       it "creates the database" do
@@ -253,8 +253,8 @@ def before_prepare
 
     describe "postgres", :postgres do
       before do
-        ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-        ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+        ENV["DATABASE_URL"] = postgres_url("_app")
+        ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
       end
 
       it "creates each database" do
diff --git a/spec/unit/hanami/cli/commands/app/db/drop_spec.rb b/spec/unit/hanami/cli/commands/app/db/drop_spec.rb
index f6458854..c596e1be 100644
--- a/spec/unit/hanami/cli/commands/app/db/drop_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/drop_spec.rb
@@ -306,8 +306,8 @@ def before_prepare
 
   describe "postgres", :postgres do
     before do
-      ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+      ENV["DATABASE_URL"] = postgres_url("_app")
+      ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
     end
 
     it "drops each database" do
@@ -427,7 +427,7 @@ def before_prepare
 
   describe "mysql", :mysql do
     before do
-      ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
+      ENV["DATABASE_URL"] = mysql_url("_app")
     end
 
     it "drops the database" do
diff --git a/spec/unit/hanami/cli/commands/app/db/migrate_spec.rb b/spec/unit/hanami/cli/commands/app/db/migrate_spec.rb
index f7dd51ba..8026f138 100644
--- a/spec/unit/hanami/cli/commands/app/db/migrate_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/migrate_spec.rb
@@ -246,8 +246,8 @@ def before_prepare
 
     describe "postgres", :postgres do
       before do
-        ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-        ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+        ENV["DATABASE_URL"] = postgres_url("_app")
+        ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
         db_create
       end
 
diff --git a/spec/unit/hanami/cli/commands/app/db/prepare_spec.rb b/spec/unit/hanami/cli/commands/app/db/prepare_spec.rb
index 6e631f14..6fe8db8f 100644
--- a/spec/unit/hanami/cli/commands/app/db/prepare_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/prepare_spec.rb
@@ -191,8 +191,8 @@ class Comments < Hanami::DB::Relation
 
   describe "postgres", :postgres do
     before do
-      ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+      ENV["DATABASE_URL"] = postgres_url("_app")
+      ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
     end
 
     context "from scratch, with structure dump and seeds" do
diff --git a/spec/unit/hanami/cli/commands/app/db/rollback_spec.rb b/spec/unit/hanami/cli/commands/app/db/rollback_spec.rb
index 9b35908f..47f69ec0 100644
--- a/spec/unit/hanami/cli/commands/app/db/rollback_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/rollback_spec.rb
@@ -351,8 +351,8 @@ class App < Hanami::App
 
   describe "postgres", :postgres do
     before do
-      ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+      ENV["DATABASE_URL"] = postgres_url("_app")
+      ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
     end
 
     context "single database" do
@@ -394,9 +394,9 @@ def before_prepare_gateways
       end
 
       before do
-        ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-        ENV["DATABASE_URL__EXTRA"] = "#{POSTGRES_BASE_URL}_extra"
-        ENV["DATABASE_URL__SUPER"] = "#{POSTGRES_BASE_URL}_super"
+        ENV["DATABASE_URL"] = postgres_url("_app")
+        ENV["DATABASE_URL__EXTRA"] = postgres_url("_extra")
+        ENV["DATABASE_URL__SUPER"] = postgres_url("_super")
 
         with_directory(@dir = make_tmp_directory) do
           write "config/app.rb", <<~RUBY
@@ -424,8 +424,8 @@ class App < Hanami::App
 
   describe "mysql", :mysql do
     before do
-      ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{MYSQL_BASE_URL}_main"
+      ENV["DATABASE_URL"] = mysql_url("_app")
+      ENV["MAIN__DATABASE_URL"] = mysql_url("_main")
     end
 
     context "single database" do
@@ -467,9 +467,9 @@ def before_prepare_gateways
       end
 
       before do
-        ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
-        ENV["DATABASE_URL__EXTRA"] = "#{MYSQL_BASE_URL}_extra"
-        ENV["DATABASE_URL__SUPER"] = "#{MYSQL_BASE_URL}_super"
+        ENV["DATABASE_URL"] = mysql_url("_app")
+        ENV["DATABASE_URL__EXTRA"] = mysql_url("_extra")
+        ENV["DATABASE_URL__SUPER"] = mysql_url("_super")
 
         with_directory(@dir = make_tmp_directory) do
           write "config/app.rb", <<~RUBY
diff --git a/spec/unit/hanami/cli/commands/app/db/structure/dump_spec.rb b/spec/unit/hanami/cli/commands/app/db/structure/dump_spec.rb
index d2de9b11..fa84ffaf 100644
--- a/spec/unit/hanami/cli/commands/app/db/structure/dump_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/structure/dump_spec.rb
@@ -217,8 +217,8 @@ def before_prepare
 
   describe "postgres", :postgres do
     before do
-      ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+      ENV["DATABASE_URL"] = postgres_url("_app")
+      ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
       db_migrate
     end
 
@@ -299,7 +299,7 @@ def before_prepare
 
   describe "mysql", :mysql do
     before do
-      ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
+      ENV["DATABASE_URL"] = mysql_url("_app")
       db_migrate
     end
 
diff --git a/spec/unit/hanami/cli/commands/app/db/structure/load_spec.rb b/spec/unit/hanami/cli/commands/app/db/structure/load_spec.rb
index a27dfdf5..a423e2a0 100644
--- a/spec/unit/hanami/cli/commands/app/db/structure/load_spec.rb
+++ b/spec/unit/hanami/cli/commands/app/db/structure/load_spec.rb
@@ -190,8 +190,8 @@ def before_prepare
 
   describe "postgres", :postgres do
     before do
-      ENV["DATABASE_URL"] = "#{POSTGRES_BASE_URL}_app"
-      ENV["MAIN__DATABASE_URL"] = "#{POSTGRES_BASE_URL}_main"
+      ENV["DATABASE_URL"] = postgres_url("_app")
+      ENV["MAIN__DATABASE_URL"] = postgres_url("_main")
       db_structure_dump
     end
 
@@ -249,7 +249,7 @@ def before_prepare
 
   describe "mysql", :mysql do
     before do
-      ENV["DATABASE_URL"] = "#{MYSQL_BASE_URL}_app"
+      ENV["DATABASE_URL"] = mysql_url("_app")
       db_structure_dump
     end