Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Cloud-init update renders secondary addresses to be incompatible with standard tools #2842

Open
ubuntu-server-builder opened this issue May 10, 2023 · 9 comments
Open

Cloud-init update renders secondary addresses to be incompatible with standard tools #2842

ubuntu-server-builder opened this issue May 10, 2023 · 9 comments
Labels
bug Something isn't working correctly launchpad Migrated from Launchpad

Comments

@ubuntu-server-builder
Copy link
Collaborator

This bug was originally filed in Launchpad as LP: #1675571

Launchpad details 
affected_projects = ['curtin', 'cloud-init (Ubuntu)', 'resolvconf (Ubuntu)', 'resolvconf (Debian)']
assignee = None
assignee_name = None
date_closed = None
date_created = 2017-03-23T21:38:47.277484+00:00
date_fix_committed = None
date_fix_released = None
id = 1675571
importance = medium
is_complete = False
lp_url = https://bugs.launchpad.net/cloud-init/+bug/1675571
milestone = None
owner = darkmuggle-deactivatedaccount
owner_name = Ben Howard
private = False
status = confirmed
submitter = darkmuggle-deactivatedaccount
submitter_name = Ben Howard
tags = []
duplicates = []

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-23T21:38:47.277484+00:00

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

[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.
@ubuntu-server-builder ubuntu-server-builder added bug Something isn't working correctly launchpad Migrated from Launchpad labels May 10, 2023
@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ryan Harper(raharper) wrote on 2017-03-23T21:54:32.954982+00:00

The network config in the previous bug used DHCP on v4 and v6; it appears this instance has a different network config injected. Can you attach the network configuration?

As a workaround, you can include a nameserver configuration

  • type: nameserver:
    address:
    • 8.8.8.8
    • 8.8.8.3

Or also include the dns-nameservers attribute in the second subnet configuration.

This will render dns-nameservers entry under lo
which will get picked up.

Given the above config, it looks like the ifupdown resolveconf hooks are not multi-iface-stanza aware.

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-23T22:27:18.460358+00:00

The following is the network_config:
'_network_config': {'config': [{'mac_address': 'ca:22:2d:f4:1a:5e',
'name': 'eth0',
'subnets': [{'address': '138.197.98.102',
'control': 'auto',
'dns_nameservers': ['8.8.8.8',
'8.8.4.4'],
'gateway': '138.197.96.1',
'netmask': '255.255.240.0',
'type': 'static'},
{'address': '10.17.0.11',
'control': 'auto',
'netmask': '255.255.0.0',
'type': 'static'}],
'type': 'physical'}],
'version': 1},

That was extracted from /var/lib/cloud/obj.pkl.

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-24T17:29:33.828255+00:00

Changing the cloud-metadata won't work in this case, since the the code for the DigitalOcean metadata source is assigning the Nameservers to the primary interface. Also, adding the DNS resolvers to the loopback interfaces doesn't work because the loopback interface is already up before the definition is added.

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-25T04:11:03.062777+00:00

Patch submitted to Cloud-init via:
https://code.launchpad.net/~utlemming/cloud-init/+git/cloud-init-1/+merge/321001

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-26T04:02:22.452809+00:00

The patch in comment #4 moves the revolvers to the loopback interface; resolve conf picks it up.

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-27T17:56:03.196354+00:00

I would like to nominate this bug for the Xenial, Yakkety and Zesty branches as well.

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-27T21:40:14.809199+00:00

So while my patch for the DigitalOcean datasource fixes this usecase, the rendering of additional addresses actually breaks all the "if*" tools for secondary addresses and even IPv6. Consider:

root@utl-ubuntu-16-04-x64-50307:# ifquery eth0
address: 138.197.91.79
gateway: 138.197.80.1
netmask: 255.255.240.0
broadcast: 138.197.95.255
root@utl-ubuntu-16-04-x64-50307:# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 4a:41:c5:1b:8a:a0 brd ff:ff:ff:ff:ff:ff
inet 138.197.91.79/20 brd 138.197.95.255 scope global eth0
valid_lft forever preferred_lft forever
inet 10.17.0.6/16 brd 10.17.255.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 2604:a880:800:10::2ced:3001/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::4841:c5ff:fe1b:8aa0/64 scope link
valid_lft forever preferred_lft forever

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-27T21:42:07.799594+00:00

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)

@ubuntu-server-builder
Copy link
Collaborator Author

Launchpad user Ben Howard(darkmuggle-deactivatedaccount) wrote on 2017-03-28T15:07:36.476197+00:00

I've withdrawn my PR for the DigitalOcean specific fix after an offline conversation.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
bug Something isn't working correctly launchpad Migrated from Launchpad
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
1 participant
@ubuntu-server-builder