Building an RPM isn’t that hard

We’re installing the Amanda backup client on a bunch of servers that I administer. We’ve decided to tunnel Amanda connections through SSH though, and that feature isn’t available in the current RPM builds that are available.

We started out compiling it from scratch on each box, and then following a bunch of steps to add the appropriate users, create directories, setup SSH keys, etc. Obviously, that gets to be a tedious process pretty quick and is prone to errors and missing steps. The obvious solution is to create an RPM for this, since that is what they are for.

Creating an RPM is pretty easy. I found some useful instructions here and here. Basically, the buildrpm package goes through the standard configure; make; make install steps for you. You can create simple shell scripts to do whatever you want at each of those processes when building the RPM. Additionaly, you can also run commands before and after RPM installation, and before and after RPM removal. For this particular script, I added a bunch of stuff to the postinstall script. As an example, here is my .spec file:

Summary: Amanda Client with SSH
Name: amanda_client_ssh
Version: 2.5.2p1
Release: 2
License: GPL
Group: Amanda Backup
Source: amanda_client_ssh-2.5.2p1.tgz

BuildRoot: %{_builddir}/%{name}-root

%description
Amanda Client compiled with SSH authentication

%prep

%setup
./configure '--a-bunch' '--of options' --'can go here'

%build
make

%install
rm -rf $RPM_BUILD_ROOT
make DESTDIR=$RPM_BUILD_ROOT install
if [[ ! -d $RPM_BUILD_ROOT/etc/amanda ]]; then
    mkdir $RPM_BUILD_ROOT/etc/amanda
fi
cat >> $RPM_BUILD_ROOT/etc/amanda/amanda-client.conf < EOF
conf "MyConfig"
index_server "backup.mydomain.com"
tape_server "backup.mydomain.com"
auth "ssh"
ssh_keys "/root/.ssh/id_rsa_amrecover"
EOF

%pre

%post
useradd -M -n -g disk -o -r -d /var/lib/amanda -s /bin/bash
        -c "Amanda user" -u 33 amanda >/dev/null 2>&1 || :

if [[ ! -d /var/lib/amanda/.ssh ]]; then
    mkdir -p /var/lib/amanda/.ssh
fi
if [[ ! -d /var/log/amanda ]]; then
    mkdir -p /var/log/amanda
fi

touch /etc/amandates

cat >> /etc/amanda/exclude <
/var/spool/mail
/tmp
EOF
mkdir ~amanda/gnutar-lists
chown amanda:disk /etc/amandates /etc/amanda/exclude ~amanda/gnutar-lists /var/log/amanda/

if [[ ! -f /root/.ssh/id_rsa_amrecover ]]; then
    ssh-keygen -t rsa -N "" -f /root/.ssh/id_rsa_amrecover
fi

cat >> /var/lib/amanda/.ssh/authorized_keys <EOF
ssh-rsa abcdefgABigLongPublicKeyGoesHere== amanda@backup.webpipe.net
EOF

%preun
userdel amanda

%clean
rm -rf $RPM_BUILD_ROOT

%files
... a bunch of files listed here ...

%changelog

It took a couple revisions of trial and error to get everything correct. That part took the longest because I didn’t see an option to skip the configure and make steps, so anytime I changed the postinstall commands it had to rebuild the whole app. But now that I’ve got the RPM, installing it should be pretty straightforward on the rest of the boxes it needs to be installed on.