From b638d6231b73d3ec663b26f991f785e5bcfb980a Mon Sep 17 00:00:00 2001
From: Zsombor Welker <fedora@zdeqb.com>
Date: Mon, 20 Jun 2022 07:23:49 +0200
Subject: [PATCH] Add explicit handling for the host network
When a container uses the host network the network configuration may not
contain an explicit "IPAddress" value. In those cases use a
pre-configured IP.
---
README.md | 1 +
src/systemd_resolved_docker/cli.py | 3 ++-
src/systemd_resolved_docker/dockerdnsconnector.py | 4 ++--
src/systemd_resolved_docker/dockerwatcher.py | 8 ++++++--
systemd-resolved-docker.sysconfig | 4 ++++
5 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/README.md b/README.md
index e3e2e1a..11e5a4e 100644
--- a/README.md
+++ b/README.md
@@ -133,6 +133,7 @@ If there are link-local, VPN or other DNS servers configured then those will als
| DOCKER_LISTEN_ADDRESS | IPs (+port) to listen on for queries from docker containers in the default network. | _ip of the default docker bridge_, often `172.17.0.1` | `172.17.0.1` or `172.17.0.1:53` |
| ALLOWED_DOMAINS | Domain which will be handled by the DNS server. If a domain starts with `.` then all subdomains will also be allowed. | `.docker` | `.docker,.local` |
| DEFAULT_DOMAIN | Domain to append to hostnames which are not allowed by `ALLOWED_DOMAINS`. | `docker` | `docker` |
+| DEFAULT_HOST_IP | IP address to use for containers on the host network if the container doesn't contain one. | `127.0.0.1` | `127.0.0.1` |
| --------------------------------- | ----------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------- | --------------------------------- |
## Install
diff --git a/src/systemd_resolved_docker/cli.py b/src/systemd_resolved_docker/cli.py
index e25c2c7..30556af 100644
--- a/src/systemd_resolved_docker/cli.py
+++ b/src/systemd_resolved_docker/cli.py
@@ -38,6 +38,7 @@ def main():
docker_listen_address = os.environ.get("DOCKER_LISTEN_ADDRESS", None)
dns_server = parse_ip_port(os.environ.get("UPSTREAM_DNS_SERVER", "127.0.0.53"))
default_domain = os.environ.get("DEFAULT_DOMAIN", "docker")
+ default_host_ip = os.environ.get("DEFAULT_HOST_IP", "127.0.0.1")
tld = os.environ.get('ALLOWED_DOMAINS', None)
if tld is None or len(tld.strip()) == 0:
@@ -64,7 +65,7 @@ def main():
resolved = SystemdResolvedConnector(systemd_resolved_interface, systemd_resolved_listen_addresses, domains, handler)
dns_connector = DockerDNSConnector(systemd_resolved_listen_addresses + docker_listen_addresses, dns_server, domains,
- default_domain, handler, cli)
+ default_domain, default_host_ip, handler, cli)
dns_connector.start()
resolved.register()
diff --git a/src/systemd_resolved_docker/dockerdnsconnector.py b/src/systemd_resolved_docker/dockerdnsconnector.py
index b40877f..7ffbadf 100644
--- a/src/systemd_resolved_docker/dockerdnsconnector.py
+++ b/src/systemd_resolved_docker/dockerdnsconnector.py
@@ -13,7 +13,7 @@ from .zoneresolver import ZoneResolver
class DockerDNSConnector:
def __init__(self, listen_addresses: List[IpAndPort], upstream_dns_server: IpAndPort, dns_domains, default_domain,
- handler, cli):
+ default_host_ip, handler, cli):
super().__init__()
self.default_domain = default_domain
@@ -35,7 +35,7 @@ class DockerDNSConnector:
server.thread_name = "%s:%s" % (ip_and_port.ip, ip_and_port.port)
self.servers.append(server)
- self.watcher = DockerWatcher(self, cli)
+ self.watcher = DockerWatcher(self, default_host_ip, cli)
def start(self):
self.watcher.start()
diff --git a/src/systemd_resolved_docker/dockerwatcher.py b/src/systemd_resolved_docker/dockerwatcher.py
index 95f3063..cee24d4 100644
--- a/src/systemd_resolved_docker/dockerwatcher.py
+++ b/src/systemd_resolved_docker/dockerwatcher.py
@@ -18,7 +18,7 @@ class DockerWatcher(Thread):
Thread based module for watching for docker container changes.
"""
- def __init__(self, handler, cli=None):
+ def __init__(self, handler, default_host_ip='127.0.0.1', cli=None):
super().__init__()
if cli is None:
@@ -26,6 +26,7 @@ class DockerWatcher(Thread):
self.daemon = True
self.handler = handler
+ self.default_host_ip = default_host_ip
self.cli = cli
def run(self) -> None:
@@ -77,7 +78,10 @@ class DockerWatcher(Thread):
for netname, network in settings.get('Networks', {}).items():
ip = network.get('IPAddress', False)
if not ip or ip == "":
- continue
+ if netname == 'host':
+ ip = self.default_host_ip
+ else:
+ continue
# record the container name DOT network
# eg. container is named "foo", and network is "demo",
diff --git a/systemd-resolved-docker.sysconfig b/systemd-resolved-docker.sysconfig
index a6845c3..fde5312 100644
--- a/systemd-resolved-docker.sysconfig
+++ b/systemd-resolved-docker.sysconfig
@@ -24,3 +24,7 @@
## will be forwarded to the configured DNS server.
## default: .docker
# ALLOWED_DOMAINS=.docker
+
+## IP address to use with host networks when an IP is not specified
+## default: 127.0.0.1
+# DEFAULT_HOST_ip=127.0.0.1
\ No newline at end of file
--
GitLab