Add support for Ubuntu 20.04

[Miouge1]

What would you like to be added:
Add support for Ubuntu 20.04

Why is this needed:
Ubuntu 20.04 will be the next LTS version of Ubuntu

[Miouge1]

I did some tests on this, as of a8a05a Ubuntu 20.04 support requires Ansible 2.8 and then fails because no packages available for 20.04 on https://download.docker.com/linux/ubuntu/dists/ yet.

After bypassing those things, deploy worked fine. So I think that once the packages are available we can go ahead and add Ubuntu 20.04 and bump Ansible requirement to 2.8. It will probably land in v2.14.

Related to #4778

Depends on docker/for-linux#940 and docker/docker-ce-packaging#443

[Miouge1]

Also worth checking: rancher/rancher#26783

[claughinghouse]

@Miouge1 it looks like Docker has been released for Ubuntu 20.04

download.docker.com

[StefanScherer]

Docker 19.03.9 is released, with packages for Ubuntu Focal Fossa.
Thanks for you patience. Enjoy!

[Miouge1]

thank you @StefanScherer!

@claudiubelu as you can see on https://download.docker.com/linux/ubuntu/dists/focal/pool/stable/amd64/ at first only containerd package was available, only since last night is the docker-ce package for Ubuntu 20.04 released ;)

I'm working on a PR to add Ubuntu 20.04 support with appropriate CI in #6157.

[aleks-sidorenko]

I'v installed kubespray to Ubuntu 20.04.
There is some minor issue: Kubelet uses wrong resolv config in Ubuntu 20.04.
In Kubespray there is file: ubuntu-18.yml with content:
kube_resolv_conf: "/run/systemd/resolve/resolv.conf"
We should have file ubuntu-20.yml with same content

[claudiubelu]

@claudiubelu as you can see on https://download.docker.com/linux/ubuntu/dists/focal/pool/stable/amd64/ at first only containerd package was available, only since last night is the docker-ce package for Ubuntu 20.04 released ;)

Hello. Sorry, why was I tagged in the first place? :)

[rdeenik]

Was able to install on Ubuntu 20.04 today as well using Kubespray using the new Docker packages and changing python-minimal to python2-minimal in bootstrap-os. Did not yet check the resolve config.

[kiaplayer]

Pods for "coredns" couldn't start with this error in logs:
[FATAL] plugin/loop: Loop (127.0.0.1:59370 -> :53) detected for zone ".",

[rdeenik]

Pods for "coredns" couldn't start with this error in logs:
[FATAL] plugin/loop: Loop (127.0.0.1:59370 -> :53) detected for zone ".",

@kiaplayer If you copy the file ubuntu-18.yml and name it ubuntu-20.yml As mentioned by @aleks-sidorenko above and run Kubespray again, this issue is solved.

[Miouge1]

As @k8s-ci-robot mentioned Ubuntu 20.04 support is merged in master. In addition to the coredns loop error, there are a couple of other things that can come up depending on your environment:

• IPVS mode not supported with the KVM kernel in Ubuntu 20.04
• Mitogen + Ubuntu 20.04 requires to specific the python interpreter path
• enable_nodelocaldns: false required in some instances

[hornpolish]

Hello Maxime (@Miouge1)

You say this as if there might be an alternative way to configure the networking (when using Ubuntu/20.04) such that it does not require IPVS. If this is true, I'd appreciate the hint. -- i tried this with no luck:

ubuntu20.04 instances on private openstack

kube_version: v1.18.5
kube_network_plugin: weave

and also with no kube_network_plugin (ie calico)

thanks for any tips/pointers/advice - i'm trying to keep one on-prem cluster at close to the bleeding edge as practical
[and thanks for the 20.04 changes you have got us so far]

As @k8s-ci-robot mentioned Ubuntu 20.04 support is merged in master. In addition to the coredns loop error, there are a couple of other things that can come up depending on your environment:

* IPVS mode not supported with the KVM kernel in Ubuntu 20.04

[JackTiber]

@hornpolish You can switch from ipvs to iptables on line 102 of the k8s-cluster.yml file in the inventory directory. I ran into this issue today while deploying a new cluster to our own OpenStack cloud and the switch to iptables fixed the issue.

You probably found this already, but leaving this comment for anyone else who comes across it.

[hornpolish]

Thanks @JackTiber -- i had kinda shelved it and went back to 18.04 which worked for me. i will give it a go next time i repave a cluster. i have a gaggle of throw-away desktops that this will be perfect for.

[LexiEmory]

Was able to install on Ubuntu 20.04 today as well using Kubespray using the new Docker packages and changing python-minimal to python2-minimal in bootstrap-os. Did not yet check the resolve config.

What did you change to use the new docker packages?

[felipecrs]

The documentation still says that it does not support 20.04.

[Miouge1]

@felipecrs that page is not updated as quickly as the README.md of Kubespray repo.

[julienlau]

I still have the issues today with kubespray master !
However the doc says that it should work with ubuntu 20.04