PostgreSQL's Perl-based TAP tests (for binaries, crash recovery, etc) are required to run under Perl versions as old as 5.8.8, which is of Debian Etch / CentOS 5 vintage. Perl does not offer good tools for backward compatibility testing on a modern Perl.
This Dockerfile produces a canned Perl 5.8.8 environment based on CentOS 5 on any host with Docker. It has ccache installed and enabled, git installed, IPC::Run installed, all the mess required to make CPAN work sensibly done, etc. So you can test your patches on oldperl.
Once you build the container once you can quickly re-use it to run test builds. You can map a postgres source tree, working tree and ccache directory from the host to make them persistent.
Understand that this container runs code fetched directly off the 'net as root, albeit root within a container, during setup. It avoids running all the perl/cpan stuff as root though, switching to a normal user as soon as it's installed the required RPMs from centos repos and rpmforge, so it's not just curl'ing random scripts into bash/perl as root.
To build the container:
mkdir pgtaptest
cp /path/to/Dockerfile pgtaptest
cd pgtaptest
docker build -t pgtaptest .
To run a shell in the container environment:
alias pgtaptest="docker run -i -t \
-v /path/to/my/postgres/tree:/pg/source \
-v /path/to/builddir:/pg/build \
-v /path/to/ccache:/pg/ccache \
pgtaptest'
pgtaptest
Once in the working environment's shell, /pg/source is the mapped source
tree, /pg/build is the mapped build tree (or an empty dir, if you didn't map
it), and /pg/ccache is the mapped ccache or - again - an empty tree if you
didn't map it.
Unmapped volumes get discarded when the container instance exits.
There's a preconfigured script, recovery-check, that configures and makes
postgres and runs the recovery tests. To run it directly from the host,
assuming you created the alias above, just:
pgtaptest recovery-check
Happy Perl 5.8'ing!