plugins:
    Database:
        driver: 'mysql'
        database: 'testdtb'
        host: '127.0.0.1'
        port: 3306
        username: 'test'
        password: 'localhost'
        connection_check_threshold: 10
        dbi_params:
            RaiseError: 1
            AutoCommit: 1
        on_connect_do: ["SET NAMES 'utf8'", "SET CHARACTER SET 'utf8'" ]
        log_queries: 1

my $users = database->quick_select('users', { id => params->{id} });

session: "DatabasePlugin"

engines:
  session:
    DatabasePlugin:
      connection: "foo"
      session_table: "SESSIONS"
      id_column:     "SESSION_ID"
      data_column:   "SESSION_DATA"

plugins:
  Database:
    connections:
      foo:
        driver:   "SQLite"
        database: "foo.sqlite"

my $foo_dbh = database('foo');
my $users = database->quick_select('users', { id => params->{id} });

Then, you can call the database keyword with the name of the database connection you want, for example:
my $foo_dbh = database('foo');
my $bar_dbh = database('bar');