From f80f7f0d82eaf05e68419c7ac87bf5d4c934b796 Mon Sep 17 00:00:00 2001 From: Ryan Harper Date: Thu, 26 Sep 2019 19:52:02 +0000 Subject: sysconfig: only write resolv.conf if network_state has DNS values If an OS image provided an /etc/resolv.conf file that was not empty cloud-init would read and re-write it with a cloud-init header even if no DNS network configuration was provided (e.g. DHCP only). This can cause problems for some network services which don't ignore cloud-init's header. LP: #1843634 --- cloudinit/net/sysconfig.py | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'cloudinit') 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): -- cgit v1.2.3