Cookbook

All the things you might need to do as an organizer or a root are documented here.

Server setup

Here is a list of things to remember when setting up servers:

• Use ssh as soon as possible.

• Work in a tmux session, this allows any other root to take over your work if needed.

• Use only one user and one shell (bash) and setup an infinite history. This, http://stackoverflow.com/a/19533853 is already installed by the rfs scripts. Doing that will document what you and the other admins are doing during the contest.

Testing on qemu/libvirt

Here are some notes:

• Do not use the spice graphical console for setting up servers, use the serial line. For syslinux it is serial 0 at the top of syslinux.cfg and for Linux console=ttyS0 on the cmd line of the kernel in syslinux.cfg.

• For best performance use the VirtIO devices (disk, NIC), this should already be configured if you used virt-install to create the machine.

• For user machines, use the QXL driver for best performance with SPICE.

User related operations

Most of the operations are made very simple with the use of udb. If you are an organizer, you can access udb in read only mode. If you are a root, you obviously have write access too.

udb displays the information (including passwords) of every contestant to organizers. Organizers can’t see the information of other organizers or roots.

All services should be using udb for authentication. Synchronization might take up to 5 minutes (usually only one minute) if anything is changed.

Giving back his password to a contestant

First of all, make sure to ask the contestant for his badge, which he should always have on him. Use the name from the badge to look up the user in the udb. The password should be visible there.

Adding an organizer

Root only. Go to udb and add a user with type orga.

Send an announce

Connect to the IRC server, join the #notify channel, and send a message formatted like this:

!announce <expiration-delay> <message>

Example:

!announce 12 The lunch is ready!

Will create an announce which will stay for 12 minutes on the users’s desktops. Note that the delay will default to 2 when not specified:

!announce No milk today :(

Machine registration

mdb contains the information of all machines on the contest LANs. If a machine is not in mdb, it is considered an alien and won’t be able to access the network.

All of these operations are root only. Organizers can’t access the mdb administration interface.

Adding a user machine to the network

In the mdb configuration, authorize self registration by adding a VolatileSetting allow_self_registration to true. Netboot the user machine - it should ask for registration details. After the details have been entered, the machine should reboot to the user environment. Disable allow_self_registration when you’re done.

Adding a machine we don’t manage to the user network

Some organizers may want to use their laptop. Ask them for their MAC address and the hostname they want. Finally, insert a mdb machine record with machine type orga using the IP address you manually allocated (if you set the last allocation to 100, you should assign the IP .100). Wait a minute for the DHCP configuration to be synced, and connect the laptop to the network.

Network FS related operations

Two kind of network file systems are used during the finals, the first one is the Root File System: RFS, the second is the Home File System: HFS. The current setup is that a server is both a RFS and a HFS node.

The RFS is a read-only NFS mounted as a rootnfs in Linux. It is replicated over multiple servers to ensure minimum latency over the network.

The HFS is a read-write, exclusive, user-specific export of their home. In other words, each user has it’s own personal space that can only be mounted once at a time. The HFS exports are sharded over multiple servers.

Resetting the hfs

If you need to delete every /home created by the hfs, simply delete all nbd files in /export/hfs/ on all HFS servers and delete entries in the user_location table of the hfs’ database:

# For each hfs instance
rm /export/hfs/*.nbd

echo 'delete from user_location;' | su - postgres -c 'psql hfs'

Remove a RAID 1

The first step is to deactivate and remove the volume group:

vgchange -a n data
vgremove data

Then you have to actually deconstruct the RAID array and zero the superblock of each device:

mdadm --stop /dev/md0
mdadm --remove /dev/md0
mdadm --zero-superblock /dev/sda2
mdadm --zero-superblock /dev/sdb2

If you want to erase the remaining ext4 filesystem on thoses devices, you can use fdisk.