From 0bb4c74e7f2d008b015d5453a1be88ae807b1f9b Mon Sep 17 00:00:00 2001 From: "Guilherme G. Piccoli" Date: Thu, 14 Feb 2019 20:37:32 +0000 Subject: EC2: Rewrite network config on AWS Classic instances every boot AWS EC2 instances' network come in 2 basic flavors: Classic and VPC (Virtual Private Cloud). The former has an interesting behavior of having its MAC address changed whenever the instance is stopped/restarted. This behavior is not observed in VPC instances. In Ubuntu 18.04 (Bionic) the network "management" changed from ENI-style (etc/network/interfaces) to netplan, and when using netplan we observe the following block present in /etc/netplan/50-cloud-init.yaml: match: macaddress: aa:bb:cc:dd:ee:ff Jani Ollikainen noticed in Launchpad bug #1802073 that the EC2 Classic instances were booting without network access in Bionic after stop/restart procedure, due to their MAC address change behavior. It was narrowed down to the netplan MAC match block, that kept the old MAC address after stopping and restarting an instance, since the network configuration writing happens by default only once in EC2 instances, in the first boot. This patch changes the network configuration write to every boot in EC2 Classic instances, by checking against the "vpc-id" metadata information provided only in the VPC instances - if we don't have this metadata value, cloud-init will rewrite the network configuration file in every boot. This was tested in an EC2 Classic instance and proved to fix the issue; unit tests were also added for the new method is_classic_instance(). LP: #1802073 Reported-by: Jani Ollikainen Suggested-by: Ryan Harper Co-developed-by: Chad Smith Signed-off-by: Guilherme G. Piccoli --- cloudinit/sources/DataSourceEc2.py | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'cloudinit') diff --git a/cloudinit/sources/DataSourceEc2.py b/cloudinit/sources/DataSourceEc2.py index eb6f27b2..4f2f6ccb 100644 --- a/cloudinit/sources/DataSourceEc2.py +++ b/cloudinit/sources/DataSourceEc2.py @@ -19,6 +19,7 @@ from cloudinit import sources from cloudinit import url_helper as uhelp from cloudinit import util from cloudinit import warnings +from cloudinit.event import EventType LOG = logging.getLogger(__name__) @@ -107,6 +108,19 @@ class DataSourceEc2(sources.DataSource): 'dynamic', {}).get('instance-identity', {}).get('document', {}) return True + def is_classic_instance(self): + """Report if this instance type is Ec2 Classic (non-vpc).""" + if not self.metadata: + # Can return False on inconclusive as we are also called in + # network_config where metadata will be present. + # Secondary call site is in packaging postinst script. + return False + ifaces_md = self.metadata.get('network', {}).get('interfaces', {}) + for _mac, mac_data in ifaces_md.get('macs', {}).items(): + if 'vpc-id' in mac_data: + return False + return True + @property def launch_index(self): if not self.metadata: @@ -320,6 +334,13 @@ class DataSourceEc2(sources.DataSource): if isinstance(net_md, dict): result = convert_ec2_metadata_network_config( net_md, macs_to_nics=macs_to_nics, fallback_nic=iface) + # RELEASE_BLOCKER: Xenial debian/postinst needs to add + # EventType.BOOT on upgrade path for classic. + + # Non-VPC (aka Classic) Ec2 instances need to rewrite the + # network config file every boot due to MAC address change. + if self.is_classic_instance(): + self.update_events['network'].add(EventType.BOOT) else: LOG.warning("Metadata 'network' key not valid: %s.", net_md) self._network_config = result -- cgit v1.2.3