Category: Sysadmin

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Careful what you call your server!

I was setting up a server recently and I was using KVM to virtualise a whole lot of hosts. Being fairly unimaginative I decided to call the machine kvm. As usual I used LVM for the disks. Now on Ubuntu this means that by default the VG will be called the same as the host name. This means the root LV will appear on the system as /dev/kvm/root.

When they KVM modules are loaded, they try and create a device called /dev/kvm. This fails pretty miserably since /dev/kvm is already a directory due to LVM shenanigans.

Not all is lost though if you’ve done a lot of setup like I had. You can rename VGs. Simply boot from your Ubuntu install CD, choose rescue mode and then jump into a shell. First you deactivate the LVs using

vgchange -a n

then you can rename the VG using

vgrename kvm kvmvg

Not sure whether I should file this problem as a bug. It is a bit of a weird situation.

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rm -rf /usr/lib

So in another case of tab completion gone wrong I ended up staring at the following on my laptop.

johnf@zoot:~/dev/vquence/metrics/trunk$ sudo rm -rf /usr/lib
^C

The command only ran for a few seconds so the damage wasn’t to bad, but what did I lose?

The locate command came to my rescue. locate runs out of cron, usually once a day, and creates a database with a list of every file on your machine. You can then use it to search for files. So to work out what was missing I did the following.

# Get the list of files before we removed them
locate --regexp '.' > /tmp/before_rm

# update the locate database
sudo updatedb

# Get the list of current files on the system
locate --regexp '.' > /tmp/after_rm

# Create a list of what's missing
diff -u /tmp/before_rm /tmp/after_rm > /tmp/diff_rm
grep '^-' /tmp/diff_rm | sed -e 's/^-//' > /tmp/missing_rm

# Ask the dpkg system what packages those files belong to
for i in `cat /tmp/missing_rm`
do
    dpkg -S $i;
done | awk '{print $1}' | sed -e 's/:$//;s/,//g' > /tmp/packages

# Reinstall those packages
sudo aptitude reinstall `cat /tmp/packages`

After this process it is probably worth running the step from updatedb again to work out what is still missing.

For the record I lost 102 files and had to reinstall 97 packages.

Now back to real work!

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Building a Private PPA on Ubuntu

One of the things I love about the Ubuntu project and launchpad is the Personal Package Archive. PPAs make it so simple and easy to backport packages. The only problem with PPAs is that they are public. I had a need to be able to host some private internal packages as well as squid with SSL support, which you can’t distribute in binary form due to licensing restrictions.

Basically I wanted to create the equivalent of an Ubuntu PPA service running on our own servers so we could place it behind our firewall. This post is basically the process I followed to integrate rebuilld and reprepro to replicate a PPA setup.

So first up install reprepro

aptitude install reprepro

next we need do create a reprepro repository

mkdir -p /srv/reprepro/{conf,incoming,incomingtmp}

Now we need to tell reprepro which distributions we care about. Create /srv/reprepro/conf/distributions with the following contents

Suite: hardy
Version: 8.04
Codename: hardy
Architectures: i386 amd64 source
Components: main
Description: Local Hardy
SignWith: repository@inodes.org
DebIndices: Packages Release . .gz .bz2
DscIndices: Sources Release .gz .bz2
Tracking: all includechanges keepsources
Log: logfile
  --changes /srv/reprepro/bin/build_sources

Suite: intrepid
Version: 8.10
Codename: intrepid
Architectures: i386 amd64 source
Components: main
Description: Local Intrepid
SignWith: repository@inodes.org
DebIndices: Packages Release . .gz .bz2
DscIndices: Sources Release .gz .bz2
Tracking: all includechanges keepsources
Log: logfile
  --changes /srv/reprepro/bin/build_sources

Suite: jaunty
Version: 9.04
Codename: jaunty
Architectures: i386 amd64 source
Components: main
Description: Local Jaunty
SignWith: repository@inodes.org
DebIndices: Packages Release . .gz .bz2
DscIndices: Sources Release .gz .bz2
Tracking: all includechanges keepsources
Log: logfile
  --changes /srv/reprepro/bin/build_sources

I also like to create reprepro options file to setup some defaults, edit /srv/reprepro/conf/options

verbose
verbose
verbose
verbose
verbose

Next we need to setup an incoming queue so that we can use dput to get the source packages into reprepro,
vi /srv/reprepro/conf/incoming

Name: incoming
IncomingDir: incoming
Allow: hardy intrepid jaunty
Cleanup: on_deny on_error
Tempdir: incomingtmp

The repository is now ready to go. So now we can setup apache. Edit /etc/apache/sites-enabled/pppa


    ServerName packages.inodes.org
    DocumentRoot /srv/reprepro

and we should also configure our sources.list to use these repositories, edit /etc/apt/sources.list

# Sources for rebuildd
deb-src http://packages.inodes.org hardy main
deb-src http://packages.inodes.org intrepid main
deb-src http://packages.inodes.org jaunty main

Next we want to setup our dput.cf to make the magic happen to get the source packages into the archive, edit ~/.dput.cf

[DEFAULT]
default_host_main = notspecified

[local]
fqdn = localhost
method = local
incoming = /srv/reprepro/incoming
allow_unsigned_uploads = 0
run_dinstall = 0
post_upload_command = reprepro -V -b /srv/reprepro processincoming incoming

So now we can do the following

apt-get source squid3
cd squid3*
dch -i # increment version number
dpkg-buildpackage -sa -S
cd ..
dput local *changes
aptitude update
apt-get source squid3

So when you run dput, first it copies the source package files to /srv/reprepro/incoming and then it gets reprepro to process it’s incoming queue. This means that the source package is now sitting in the repository.
So the second apt-get source should have downloaded the source package from our local repository which is exactly what rebuildd will do before it tries to build it.

Next step is to setup rebuildd so that it builds the binary packages and installs them into the repository.

aptitude install rebuildd

Setup so it runs out of init.d and the releases we care about, edit /etc/default/rebuildd

START_REBUILDD=1
START_REBUILDD_HTTPD=1
DISTS="hardy intrepid jaunty"

Now when a source package is uploaded into the repository we want to kick off rebuildd to build the package. We can do this through the reprepro log hooks. You’ll notice in the conf/distributions above the following lines.

Log: logfile
  --changes /srv/reprepro/bin/build_sources

This script will be run any time a .changes file is added to the repository. Create /srv/reprepro/bin/build_sources

#!/bin/bash

action=$1
release=$2
package=$3
version=$4
changes_file=$5

# Only care about packages being added
if [ "$action" != "accepted" ]
then
	exit 0
fi

# Only care about source packages
echo $changes_file | grep -q _source.changes
if [ $? = 1 ]
then
	exit 0
fi

# Kick off the job
echo "$package $version 1 $release"  | sudo rebuildd-job add

This script basically checks the right type of package is being added. Then it calls rebuildd-job to ask for that specific package and version to be built for that Ubuntu release.

Now the first thing that rebuildd does is download the source for the package. However we need to update the sources first since our server doesn’t know there are new files in the repository yet. So edit /etc/rebuildd/rebuilddrv an change

apt-get -q --download-only -t ${d} source ${p}=${v}

to

source_cmd = /srv/reprepro/bin/get_sources ${d} ${p} ${v}

and create /srv/reprepro/bin/get_sources with

#!/bin/bash

d=$1
p=$2
v=$3

sudo aptitude update >/dev/null
apt-get -q --download-only -t ${d} source ${p}=${v}

By this stage we have rebuildd building packages but we need to make sure they get re-injected back into the repository. We can do this with a post script. Edit /etc/rebuildd/rebuilddrc

post_build_cmd = /srv/reprepro/bin/upload_binaries ${d} ${p} ${v} ${a}

and create /srv/reprepro/bin/upload_binaries

#!/bin/bash

d=$1
p=$2
v=$3
a=$4

su -l -c "reprepro -V -b /srv/reprepro include ${d} /var/cache/pbuilder/result/${p}_${v}_${a}.changes" johnf

Now the su is in there because rebuildd needs to be able to access the GPG passphrase to sign the repository with. So rather than have a passphrase-less key we make sure that gpg-agent is running by adding the following to your .profile.

if test -f $HOME/.gpg-agent-info &&    kill -0 `cut -d: -f 2 $HOME/.gpg-agent-info` 2>/dev/null; then
	GPG_AGENT_INFO=`cat $HOME/.gpg-agent-info`
	export GPG_AGENT_INFO
else
	eval `gpg-agent --daemon`
	echo $GPG_AGENT_INFO >$HOME/.gpg-agent-info
fi

GPG_TTY=`tty`
export GPG_TTY

So that’s it you now have your own personal PPA. Just in case you had fallen asleep. Here is a little script I wrote so you can auto build the source packages for each release you care about in one go.

#!/bin/bash

set -e

RELEASES="hardy intrepid jaunty"

if [ ! -f debian/changelog ]
then
	echo "This isn't a debian repo"
	exit 1
fi

# Check for changes
if [ `bzr st | wc -l` != "0" ]
then
	echo "You have uncommitted changes!"
	exit 1
fi

if [ -d ../tmpbuild ]
then
	echo "The tmpbuild dir exists"
	exit 1
fi

bzr export ../tmpbuild
cp debian/changelog ../tmpbuild.changelog
cd ../tmpbuild

PACKAGE=`head -1 debian/changelog | awk '{print $1}'`
VERSION=`head -1 debian/changelog | awk '{print $2}' | sed -r -e 's/^(//;s/)$//'`

for release in $RELEASES
do
	
	sed -r -e "1s/) [^;]+; /~${release}) ${release}; /" ../tmpbuild.changelog > debian/changelog 
	head -1 debian/changelog
	dpkg-buildpackage -S -sa
	dput local ../${PACKAGE}_${VERSION}~${release}_source.changes
done

cd ..
rm -rf tmpbuild

So the above documentation is a bit of a brain dump on what I’ve been working on for the past 2 days and I’m sure I’ve left some bits out. So please give me any feedback you have in the comments.

Posted on

Melbourne Cup Dip2

To quote Justaan:

This is what we call the Melbourne Cup Network Effect

Melbourne Cup network effect

It seems it really is the race that stops the nation. This is a graph of Bulletproof’s outbound web traffic for today. That’s a 37% drop in outbound traffic just after 3pm.

Make sure you take note of my l33t gimp skills!