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-rw-r--r--cloudinit/net/sysconfig.py6
-rw-r--r--tests/unittests/test_net.py12
2 files changed, 16 insertions, 2 deletions
diff --git a/cloudinit/net/sysconfig.py b/cloudinit/net/sysconfig.py
index 416c1c97..87b548e5 100644
--- a/cloudinit/net/sysconfig.py
+++ b/cloudinit/net/sysconfig.py
@@ -577,6 +577,10 @@ class Renderer(renderer.Renderer):
@staticmethod
def _render_dns(network_state, existing_dns_path=None):
+ # skip writing resolv.conf if network_state doesn't include any input.
+ if not any([len(network_state.dns_nameservers),
+ len(network_state.dns_searchdomains)]):
+ return None
content = resolv_conf.ResolvConf("")
if existing_dns_path and os.path.isfile(existing_dns_path):
content = resolv_conf.ResolvConf(util.load_file(existing_dns_path))
@@ -584,8 +588,6 @@ class Renderer(renderer.Renderer):
content.add_nameserver(nameserver)
for searchdomain in network_state.dns_searchdomains:
content.add_search_domain(searchdomain)
- if not str(content):
- return None
header = _make_header(';')
content_str = str(content)
if not content_str.startswith(header):
diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index a093cf10..b6597412 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -2701,6 +2701,10 @@ USERCTL=no
ns = network_state.parse_net_config_data(CONFIG_V1_EXPLICIT_LOOPBACK)
render_dir = self.tmp_path("render")
os.makedirs(render_dir)
+ # write an etc/resolv.conf and expect it to not be modified
+ resolvconf = os.path.join(render_dir, 'etc/resolv.conf')
+ resolvconf_content = "# Original Content"
+ util.write_file(resolvconf, resolvconf_content)
renderer = self._get_renderer()
renderer.render_network_state(ns, target=render_dir)
found = dir2dict(render_dir)
@@ -2718,6 +2722,8 @@ TYPE=Ethernet
USERCTL=no
"""
self.assertEqual(expected, found[nspath + 'ifcfg-eth0'])
+ # a dhcp only config should not modify resolv.conf
+ self.assertEqual(resolvconf_content, found['/etc/resolv.conf'])
def test_bond_config(self):
expected_name = 'expected_sysconfig_rhel'
@@ -3202,6 +3208,10 @@ USERCTL=no
ns = network_state.parse_net_config_data(CONFIG_V1_EXPLICIT_LOOPBACK)
render_dir = self.tmp_path("render")
os.makedirs(render_dir)
+ # write an etc/resolv.conf and expect it to not be modified
+ resolvconf = os.path.join(render_dir, 'etc/resolv.conf')
+ resolvconf_content = "# Original Content"
+ util.write_file(resolvconf, resolvconf_content)
renderer = self._get_renderer()
renderer.render_network_state(ns, target=render_dir)
found = dir2dict(render_dir)
@@ -3219,6 +3229,8 @@ TYPE=Ethernet
USERCTL=no
"""
self.assertEqual(expected, found[nspath + 'ifcfg-eth0'])
+ # a dhcp only config should not modify resolv.conf
+ self.assertEqual(resolvconf_content, found['/etc/resolv.conf'])
def test_bond_config(self):
expected_name = 'expected_sysconfig_opensuse'