Machine/bender

Hostnames

bender.sugarlabs.org

Hardware

HPE ProLiant DL360 Gen10 1RU server
- Dual socket, current configuration has one CPU
Xeon Gold 5218R
- 20 cores/40 threads
- 2.1GHz base frequency, 4.0GHz max turbo frequency
- 27.5MB of cache
64GB RAM
2TB NVMe SSD
Ubuntu 20.04.2 LTS

Location

Hosted by Develer

Admins

Bernie Innocenti, _bernie on #sugar Freenode
Daniel Narvaez, dnarvaez on #sugar Freenode
Stefano Fedrigo <aleph AT develer.com>, sometimes _aleph on Freenode (local access, office hours CET)
Develer Infrastructure <it AT lists.develer.com> (local access, office hours CET)

Network configuration

Develer has a 10mbit up/downlink and asks to limit bandwidth usage from hosted services. There is a traffic shaper, but it may have trouble shaping 6to4 traffic.

Bender is globally accessible through public, static IPv4 as well as the 6to4 subnet associated to it: 2002:5395:9edc::/48.

The tun6to4 interface on bender is assigned the globally visible address 2002:5395:9edc::1. The subnet 2002:5395:9edc:1::/64 of our 6to4 net is assigned to the bridge virbr0, which binds together several virtual interfaces connected to the libvirt guests. With this network setup, IPv6 routing works naturally, without the need to add any special routing rules on bender.

The virbr0 bridge is created by libvirt on startup with /etc/libvirt/qemu/networks/default.xml. Libvirt does not yet support assigning IPv6 addresses to bridges, therefore we do this in /etc/rc.local:

ip addr add 2002:5395:9edc:1::1/64 dev virbr0

To automatically configure network and on the gursts, Bender also runs radvd, the IPv6 Routing Advertisement daemon. The contents of /etc/radvd.conf are:

interface virbr0
{
       IgnoreIfMissing on;
       AdvSendAdvert on;
       MinRtrAdvInterval 30;
       MaxRtrAdvInterval 100;
       AdvDefaultPreference low;
       AdvHomeAgentFlag off;
       
       #bernie: subnet 1 of our /48 6to4 on Develer Consiagnet
       prefix 2002:5395:9edc:1::1/64
       {
               AdvOnLink on;
               AdvAutonomous on;
       };
};

Guests simply need to be configured to accept IPv6 routing advertisements. The DNS must be assigned manually.

Hosted VMs

All buildslaves currently run off bender as KVM virtual machines managed by libvirtd.

The machines are not globally addressable on IPv4 and are only reachable by IPv6. The IPv6 address is dynamically configured by radvd to a subnet of the public 6to4 net.

All the VMs are in /srv/images. See the README in the same directory.

They have been created with

virt-install --name buildslave-name --ram 512 \
--disk path=/srv/images/buildslave-name.img,size=10
--network network:default \
--location "mirror-http-address" \
--extra-args="console=tty0 console=ttyS0,115200n8 serial"