Additionally, "ifconfig" no longer shows secondary addresses. Notice that `10.17.0.6/16` in #7 above is not defined:
root@utl-ubuntu-16-04-x64-50307:~# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 4a:41:c5:1b:8a:a0 inet addr:138.197.91.79 Bcast:138.197.95.255 Mask:255.255.240.0 inet6 addr: fe80::4841:c5ff:fe1b:8aa0/64 Scope:Link inet6 addr: 2604:a880:800:10::2ced:3001/64 Scope:Global UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:844 errors:0 dropped:0 overruns:0 frame:0 TX packets:653 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:107141 (107.1 KB) TX bytes:91481 (91.4 KB) ** Summary changed: - 0.7.9-48-g1c795b9-0ubuntu1~16.04.1 with multiple eth0 definitions has no resolvers + Cloud-init update renders secondary addresses ti be incompatible with standard tools ** Description changed: + The change of how cloud-init renders /etc/network/interface.d/50-cloud-init.cfg, standard tools no longer work as expected: + * resolvconf will nullify nameservers + * if* commands ignore secondary addresses + + The rendering is considered dangerous per Debian (https://wiki.debian.org/NetworkConfiguration), to whit: + "Also, ifupdown supports specifying multiple interfaces by repeating iface sections with the same interface name. The key difference from the method described above is that all such sections are treated by ifupdown as just one interface, so user can't add or remove them individually. However, up/down commands, as well as scripts, are called for every section as it used to be. + + "Note however that this method is dangerous! Certain driver/hardware combinations may sometimes fail to bring the link up if no labels are assigned to the alias interfaces. (Seen this on Debian Wheezy and Jessie with RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 01) auto-negotiating to 10/full. A similar warning from another person exists in the history of this page.) + " + + + [ORIGINAL REPORT] + Regresion from Bug #1657940. When provisioning with multiple eth0 addresses, /etc/resolv.conf is empty: Consider: root@tester:~# cat /etc/network/interfaces.d/50-cloud-init.cfg # This file is generated from information provided by # the datasource. Changes to it will not persist across an instance. # To disable cloud-init's network configuration capabilities, write a file # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following: # network: {config: disabled} auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 138.197.98.102 dns-nameservers 8.8.8.8 8.8.4.4 gateway 138.197.96.1 netmask 255.255.240.0 # control-alias eth0 iface eth0 inet static address 10.17.0.11 netmask 255.255.0.0 Which then yields an empty /etc/resolv.conf: root@tester:/run/resolvconf# cat interface/eth0.inet root@tester:/run/resolvconf# cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN The problem is that resolvconfg does pattern matching for eth*.inet. The second definition of eth0 has no nameserver and therefore overrides the definition. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1675571 Title: Cloud-init update renders secondary addresses ti be incompatible with standard tools To manage notifications about this bug go to: https://bugs.launchpad.net/cloud-init/+bug/1675571/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs