Add new option to manually expose the DNS port to the host, remove bi…

…nding by default (#11011)

localstack-core/localstack/cli/localstack.py

@@ -457,6 +457,13 @@ def _print_service_table(services: Dict[str, str]) -> None:
     multiple=True,
     required=False,
 )
+@click.option(
+    "--host-dns",
+    help="Expose the LocalStack DNS server to the host using port bindings.",
+    required=False,
+    is_flag=True,
+    default=False,
+)
 @publish_invocation
 def cmd_start(
     docker: bool,
@@ -467,6 +474,7 @@ def cmd_start(
     env: Tuple = (),
     publish: Tuple = (),
     volume: Tuple = (),
+    host_dns: bool = False,
 ) -> None:
     """
     Start the LocalStack runtime.

localstack-core/localstack/utils/bootstrap.py

@@ -31,10 +31,10 @@
     VolumeMappings,
 )
 from localstack.utils.container_utils.docker_cmd_client import CmdDockerClient
-from localstack.utils.docker_utils import DOCKER_CLIENT, container_ports_can_be_bound
+from localstack.utils.docker_utils import DOCKER_CLIENT
 from localstack.utils.files import cache_dir, mkdir
 from localstack.utils.functions import call_safe
-from localstack.utils.net import Port, get_free_tcp_port, get_free_tcp_port_range
+from localstack.utils.net import get_free_tcp_port, get_free_tcp_port_range
 from localstack.utils.run import is_command_available, run, to_str
 from localstack.utils.serving import Server
 from localstack.utils.strings import short_uid
@@ -548,28 +548,6 @@ def _cfg(cfg: ContainerConfiguration):
 
         return _cfg
 
-    @staticmethod
-    def publish_dns_ports(cfg: ContainerConfiguration):
-        dns_ports = [
-            Port(config.DNS_PORT, protocol="udp"),
-            Port(config.DNS_PORT, protocol="tcp"),
-        ]
-        if container_ports_can_be_bound(dns_ports, address=config.DNS_ADDRESS):
-            # expose the DNS server to the host
-            # TODO: update ContainerConfiguration to support multiple PortMappings objects with different bind addresses
-            docker_flags = []
-            for port in dns_ports:
-                docker_flags.extend(
-                    [
-                        "-p",
-                        f"{config.DNS_ADDRESS}:{port.port}:{port.port}/{port.protocol}",
-                    ]
-                )
-            if cfg.additional_flags is None:
-                cfg.additional_flags = " ".join(docker_flags)
-            else:
-                cfg.additional_flags += " " + " ".join(docker_flags)
-
     @staticmethod
     def container_name(name: str):
         def _cfg(cfg: ContainerConfiguration):
@@ -693,6 +671,10 @@ def _cfg(cfg: ContainerConfiguration):
             if params.get("network"):
                 cfg.network = params.get("network")
 
+            if params.get("host_dns"):
+                cfg.ports.add(config.DNS_PORT, config.DNS_PORT, "udp")
+                cfg.ports.add(config.DNS_PORT, config.DNS_PORT, "tcp")
+
             # processed parsed -e, -p, and -v flags
             ContainerConfigurators.env_cli_params(params.get("env"))(cfg)
             ContainerConfigurators.port_cli_params(params.get("publish"))(cfg)
@@ -1186,7 +1168,6 @@ def configure_container(container: Container):
             ContainerConfigurators.service_port_range,
             ContainerConfigurators.mount_localstack_volume(config.VOLUME_DIR),
             ContainerConfigurators.mount_docker_socket,
-            ContainerConfigurators.publish_dns_ports,
             # overwrites any env vars set in the config that were previously set by configurators
             ContainerConfigurators.config_env_vars,
             # ensure that GATEWAY_LISTEN is taken from the config and not

tests/cli/test_cli.py

@@ -1,8 +1,6 @@
 import json
 import logging
 import os.path
-import socket
-from contextlib import closing
 
 import pytest
 import requests
@@ -12,13 +10,13 @@
 from localstack import config, constants
 from localstack.cli.localstack import localstack as cli
 from localstack.config import Directories, in_docker
-from localstack.constants import LOCALHOST_HOSTNAME, LOCALHOST_IP, MODULE_MAIN_PATH, TRUE_STRINGS
+from localstack.constants import MODULE_MAIN_PATH, TRUE_STRINGS
 from localstack.utils import bootstrap
 from localstack.utils.bootstrap import in_ci
 from localstack.utils.common import poll_condition
 from localstack.utils.container_utils.container_client import ContainerClient, NoSuchImage
 from localstack.utils.files import mkdir
-from localstack.utils.net import get_free_udp_port, send_dns_query
+from localstack.utils.net import get_free_udp_port
 from localstack.utils.run import run, to_str
 
 LOG = logging.getLogger(__name__)
@@ -238,61 +236,26 @@ def test_start_cli_within_container(self, runner, container_client, tmp_path):
 
 @pytest.mark.skipif(condition=in_docker(), reason="cannot run CLI tests in docker")
 class TestDNSServer:
-    def test_dns_port_published(self, runner, container_client, monkeypatch):
+    def test_dns_port_published_with_flag(self, runner, container_client, monkeypatch):
         port = get_free_udp_port()
         monkeypatch.setenv("DEBUG", "1")
         monkeypatch.setenv("DNS_PORT", str(port))
         monkeypatch.setattr(config, "DNS_PORT", port)
 
-        runner.invoke(cli, ["start", "-d"])
+        runner.invoke(cli, ["start", "-d", "--host-dns"])
         runner.invoke(cli, ["wait", "-t", "60"])
 
         inspect = container_client.inspect_container(config.MAIN_CONTAINER_NAME)
         assert f"{port}/udp" in inspect["HostConfig"]["PortBindings"]
 
-    @pytest.mark.skip(reason="For this change, the tests run on the previous image")
-    def test_dns_server_custom_port(self, runner, container_client, monkeypatch):
-        port = get_free_udp_port()
+    def test_dns_port_not_published_by_default(self, runner, container_client, monkeypatch):
         monkeypatch.setenv("DEBUG", "1")
-        monkeypatch.setenv("DNS_PORT", str(port))
-        monkeypatch.setattr(config, "DNS_PORT", port)
 
         runner.invoke(cli, ["start", "-d"])
         runner.invoke(cli, ["wait", "-t", "60"])
 
-        reply = send_dns_query(name=LOCALHOST_HOSTNAME, port=port)
-        assert str(reply.a.rdata) == LOCALHOST_IP
-
-    @pytest.mark.skip(reason="For this change, the tests run on the previous image")
-    def test_dns_server_starts_if_host_port_bound(
-        self, runner, container_client, monkeypatch, dns_query_from_container
-    ):
-        port = get_free_udp_port()
-        monkeypatch.setenv("DEBUG", "1")
-        monkeypatch.setenv("DNS_PORT", str(port))
-        monkeypatch.setattr(config, "DNS_PORT", port)
-
-        # bind the port
-        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        s.bind(("", port))
-
-        with closing(s):
-            runner.invoke(cli, ["start", "-d"])
-            runner.invoke(cli, ["wait", "-t", "60"])
-
-            inspect = container_client.inspect_container(config.MAIN_CONTAINER_NAME)
-            assert f"{port}/udp" not in inspect["HostConfig"]["PortBindings"]
-            ip_address = list(inspect["NetworkSettings"]["Networks"].values())[0]["IPAddress"]
-
-            with pytest.raises(TimeoutError):
-                send_dns_query(name=LOCALHOST_HOSTNAME, port=port)
-
-            # use a docker container to test the DNS
-            stdout, _ = dns_query_from_container(
-                name=LOCALHOST_HOSTNAME, ip_address=ip_address, port=port
-            )
-            assert ip_address in stdout.decode().splitlines()
+        inspect = container_client.inspect_container(config.MAIN_CONTAINER_NAME)
+        assert "53/udp" not in inspect["HostConfig"]["PortBindings"]
 
 
 class TestHooks: