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Using ifupdown2 on Ubuntu

ifupdown2 improves network configuration for standard Debian and Ubuntu instances and is the standard interface configuration tool for Cumulus Linux since release 2.1. This article describes how to install ifupdown2 on Ubuntu hosts.

Verify Ubuntu Version

Before you start the install, verify the version of Ubuntu installed on the instance:

user@host:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"

Follow the appropriate instructions below for your installed version of Ubuntu.

Installing ifupdown2 on an Ubuntu Host

Ubuntu 16.04 Xenial

The default package list for Ubuntu 16.04 includesifupdown2. The package is available here: ifupdown2.

  1. Open /etc/apt/sources.list in an editor.

  2. Uncomment the following line, and save the file:

     deb http://us.archive.ubuntu.com/ubuntu/ xenial universe

  3. Update the Ubuntu instance:

    user@host:~$ sudo apt-get update

  4. Install the ifupdown2 package:

    user@host:~$ sudo apt-get install ifupdown2

  5. Make sure the following configuration is present in the systemd file:

    [Unit]
Description=ifupdown2 init script
    
[Service]
Type=oneshot
ExecStart=/sbin/ifup -a
ExecStop=/sbin/ifdown -a
RemainAfterExit=yes
    
[Install]
WantedBy=multi-user.target

Ubuntu 14.04 Trusty

The default package list for Ubuntu 14.04 does not include ifupdown2. However, as Ubuntu 16.04 includes it, you can work around this restriction by upgrading.

An Ansible playbook is available to automate these tasks.

  1. Enter the root account. The remaining commands in these instructions assume use of the root account.

  2. Add the Ubuntu Xenial sources to your Ubuntu Trusty installation:

    root@host# echo "deb http://us.archive.ubuntu.com/ubuntu/ xenial universe" > /etc/apt/sources.list.d/xenial.list

  3. Update the Ubuntu package cache. You might see warnings in the output, which you can ignore:

    root@host# apt-get update
<snip>
Ign http://us.archive.ubuntu.com trusty/multiverse Translation-en_US
Ign http://us.archive.ubuntu.com trusty/restricted Translation-en_US
Ign http://us.archive.ubuntu.com trusty/universe Translation-en_US
Reading package lists... Done 
W: Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin'
W: Ignoring Provides line with DepCompareOp for package php-psr-http-message-implementation
W: Ignoring Provides line with DepCompareOp for package php-psr-log-implementation
W: Ignoring Provides line with DepCompareOp for package php-math-biginteger
W: Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin'
W: You may want to run apt-get update to correct these problems

  4. Important: After the initial configuration, the repositories have equal preference for installing packages, resulting in the installation of the newest (Xenial) packages. As the goal of this article is to install ifupdown2 only, this step ensures that you install the Trusty packages first.

    Before continuing, you must either raise the priority for the Trusty repository  or lower the priority of the Xenial repository. The example steps below show how to lower the priority of the Xenial repository, ensuring you install the Trusty packages first, and Xenial packages are only installed if no Trusty package exists:

    1. Create a file called /etc/apt/preferences.d/xenial and add the following text to the file, then save the file:

      Explanation: give xenial a low priority number
Package: *
Pin: release a=xenial
Pin-Priority: 100

      Or, run this command to perform the same task:

      root@host# echo -e "Explanation: give xenial a low priority number\nPackage: *\nPin: release a=xenial\nPin-Priority: 100\n" > /etc/apt/preferences.d/xenial

    2. Verify that Xenial packages do not override all other packages. The example below uses the Ansible package for verification, as different versions are available on Trusty (Ansible 1.5.4), and Xenial (Ansible 1.9.4):

      root@host# apt-cache policy ansible
ansible:
  Installed: (none)
  Candidate: 1.5.4+dfsg-1
  Version table:
     1.9.4-1 0
        100 http://us.archive.ubuntu.com/ubuntu/ xenial/universe amd64 Packages
     1.7.2+dfsg-1~ubuntu14.04.1 0
        100 http://us.archive.ubuntu.com/ubuntu/ trusty-backports/universe amd64 Packages
     1.5.4+dfsg-1 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages

      The Candidate above is 1.5.4, and you lowered the Xenial priority from 500 to 100, which means that Xenial packages do not override Trusty repository packages.

  5. Install the ifupdown2 package dependencies:

    root@host# apt-get install python-ipaddr python-argcomplete python-gvgen python-mako

  6. Place a hold on the ifupdown package:

    root@host# echo ifupdown hold | dpkg --set-selections

  7. Download the ifupdown2 package:

    root@host# apt-get download ifupdown2

  8. Manually install the ifupdown2 package:

    root@host# dpkg --force-conflicts --force-depends --force-overwrite -i ./ifupdown2*.deb
Selecting previously unselected package ifupdown2.
dpkg: considering removing ifupdown in favour of ifupdown2 ...
dpkg: warning: ignoring dependency problem with removal of ifupdown:
 upstart depends on ifupdown (>= 0.6.10ubuntu5)
 ifupdown is to be removed.
    
Package ifupdown is on hold, not touching it. Use --force-hold to override.
dpkg: regarding .../ifupdown2_1.0~git20151029-1_all.deb containing ifupdown2:
 ifupdown2 conflicts with ifupdown
 ifupdown (version 0.7.47.2ubuntu4.1) is present and installed.
    
dpkg: warning: ignoring conflict, may proceed anyway!
(Reading database ... 197912 files and directories currently installed.)
Preparing to unpack .../ifupdown2_1.0~git20151029-1_all.deb ...
Unpacking ifupdown2 (1.0~git20151029-1) ...
Replacing files in old package ifupdown (0.7.47.2ubuntu4.1) ...
dpkg: ifupdown2: dependency problems, but configuring anyway as you requested:
 ifupdown2 depends on init-system-helpers (>= 1.18~); however:
 Version of init-system-helpers on system is 1.14.
    
Setting up ifupdown2 (1.0~git20151029-1) ...
Installing new version of config file /etc/init.d/networking ...
update-rc.d: warning: default start runlevel arguments (2 3 4 5) do not match networking Default-Start values (S)
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Processing triggers for ureadahead (0.100.0-16) ...
ureadahead will be reprofiled on next reboot

  9. Examine the “Depends” and “Conflicts” lines from the installed ifupdown2 package.

    root@host# grep -A 34 "Package: ifupdown2" /var/lib/dpkg/status
    Package: ifupdown2
    Status: install ok installed
    Priority: optional
    Section: admin
    Installed-Size: 595
    Maintainer: Ubuntu Developers 
    Architecture: all
    Version: 1.0~git20151029-1
    Replaces: ifupdown
    Provides: ifupdown
    Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr
    Suggests: python-gvgen, python-mako
    Conflicts: ifupdown
    Conffiles:
    /etc/default/networking/networking.default 76a6935f125a8db5cbcddee1d422fc81
    /etc/init.d/networking 703fab9e50c7c539efc6e1ce6b9c7633
    /etc/network/ifupdown2/addons.conf c39be66aa58f59b4343c9dc6541043fe
    /etc/network/ifupdown2/ifupdown2.conf 85fd2d75c77c6b68438a16888ae08510
    Description: Network Interface Management tool similar to ifupdown
     ifupdown2 is ifupdown re-written in Python. It replaces ifupdown and provides
     the same user interface as ifupdown for network interface configuration.
     Like ifupdown, ifupdown2 is a high level tool to configure (or, respectively
     deconfigure) network interfaces based on interface definitions in
     /etc/network/interfaces. It is capable of detecting network interface
     dependencies and comes with several new features which are available as
     new command options to ifup/ifdown/ifquery commands. It also comes with a new
     command ifreload to reload interface configuration with minimum
     disruption. Most commands are also capable of input and output in JSON format.
     It is backward compatible with ifupdown /etc/network/interfaces format and
     supports newer simplified format. It also supports interface templates with
     python-mako for large scale interface deployments. See
     /usr/share/doc/ifupdown2/README.rst for details about ifupdown2. Examples
     are available under /usr/share/doc/ifupdown2/examples.
     Original-Maintainer: Roopa Prabhu 
     Homepage: https://github.com/CumulusNetworks/ifupdown2

  10. Optional: At this point you need to amend the package manager’s understanding of the dependencies and conflicts for the ifupdown2 package. This requires two very precise edits to the /var/lib/dpkg/status file. To ensure that those edits produce the desired changes, first confirm that the two find-and-replaces that you are performing in Step 11 each only have one instance to replace.

    root@host# grep -c "Conflicts: ifupdown" /var/lib/dpkg/status
1
root@host# grep -c "Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr" /var/lib/dpkg/status
1

  11. Update the package manager with new dependency and conflict information for the ifupdown2 package by using the sed command to find and replace the two lines (shown in red during Step 9):

    root@host# sed -i "s/Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr/Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.14~), python-argcomplete, python-ipaddr/g" /var/lib/dpkg/status

root@host# sed -i "/Conflicts: ifupdown/d" /var/lib/dpkg/status

  12. Confirm you made your edits to the file successfully. Note that you changed the minimum required init-system-helpers version from 1.18 to 1.14 and you removed the Conflicts line when compared to Step 9:

    root@host# grep -A 34 "Package: ifupdown2" /var/lib/dpkg/status
Package: ifupdown2
Status: install ok installed
Priority: optional
Section: admin
Installed-Size: 595
Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
Architecture: all
Version: 1.0~git20151029-1
Replaces: ifupdown
Provides: ifupdown
Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.14~), python-argcomplete, python-ipaddr
Suggests: python-gvgen, python-mako
Conffiles:
 /etc/default/networking/networking.default 76a6935f125a8db5cbcddee1d422fc81
 /etc/init.d/networking 703fab9e50c7c539efc6e1ce6b9c7633
 /etc/network/ifupdown2/addons.conf c39be66aa58f59b4343c9dc6541043fe
 /etc/network/ifupdown2/ifupdown2.conf 85fd2d75c77c6b68438a16888ae08510
Description: Network Interface Management tool similar to ifupdown
 ifupdown2 is ifupdown re-written in Python. It replaces ifupdown and provides
 the same user interface as ifupdown for network interface configuration.
 Like ifupdown, ifupdown2 is a high level tool to configure (or, respectively
 deconfigure) network interfaces based on interface definitions in
 /etc/network/interfaces. It is capable of detecting network interface
 dependencies and comes with several new features which are available as
 new command options to ifup/ifdown/ifquery commands. It also comes with a new
 command ifreload to reload interface configuration with minimum
 disruption. Most commands are also capable of input and output in JSON format.
 It is backward compatible with ifupdown /etc/network/interfaces format and
 supports newer simplified format. It also supports interface templates with
 python-mako for large scale interface deployments. See
 /usr/share/doc/ifupdown2/README.rst for details about ifupdown2. Examples
 are available under /usr/share/doc/ifupdown2/examples.
Original-Maintainer: Roopa Prabhu <roopa@cumulusnetworks.com>
Homepage: https://github.com/CumulusNetworks/ifupdown2

  13. Disable the Xenial package repository until you need it again:

    root@host# sed -i "s/deb/#deb/g" /etc/apt/sources.list.d/xenial.list

  14. Update the Ubuntu package cache again to remove the Xenial sources from the package cache.

    root@host# apt-get update

Verifying ifupdown2

After the ifupdown2 installation finishes, you can use ifupdown2-specific commands to test and verify:

user@host:~$ sudo ifquery -ra
auto lo
iface lo inet loopback
    mtu 65536

auto eth0
iface eth0
    address 10.50.10.160/24
    link-speed 1000
    link-duplex full
    link-autoneg on

Installing Other Tools

In addition, you can install the brctl and bridge commands so the host more closely resembles Cumulus Linux. These commands let you get information and configure your bridges:

user@host:~$ sudo apt-get install bridge-utils

You can now review bridges on the host in the same way as in Cumulus Linux:

user@host:~$ ifquery -a
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto bridge
iface bridge
    bridge-ports eth1
    bridge-stp on

Use the brctl command to look at the bridge STP state:

user@host:~$ brctl show
bridge name bridge id       STP enabled interfaces
bridge      8000.080027d73d5d   yes     eth1

Removing ifupdown2

  1. Remove the package in the normal Debian/Ubuntu manner:

    sudo apt-get remove ifupdown2

  2. On Ubuntu 14.04 only:

    sudo apt-get install ifupdown --reinstall

Further Reading

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