Proxying DBI with DBD::Gofer and App::Staticperl

Proxying DBI with DBD::Gofer and App::Staticperl

• 1.
  Proxying DBI withDBD::Gofer and App::Staticperl San Diego.pm talk May 17, 2012
• 2.
  Environment • Need toconnect to Informix IDS servers • Remote systems with strict firewalls • Production systems, no configuration change possible • Minimal footprint required for maintenance • Sounds complicated? Because it is.
• 3.
  Solution: DBD::Gofer • StatelessDBI proxy • Works by changing DSN connect string • Or even setting DBI_AUTOPROXY environment variable • Transparent for DBI applications • Support different transports • One of them is “stream” (SSH)
• 4.
  Server side • Needs to have Perl with recent enough DBI • Needs database specific DBD (DBD::Informix) • System Perl is Untouchable, period • Custom Perl build litters a lot • Maintenance is PITA • Answer: App::Staticperl
• 5.
  App::Staticperl • Marc Lehmann’s Yet Another brilliant work • Allows building all-in-one Perl executable • Including pure Perl modules • Including XS modules and shared objects (!) • Not unlike PAR::Packer, but actually works • Unlike PAR, no zips and no write permission required
• 6.
  App::Staticperl gotchas • Notvery mature: may or may not work for your specific application • May take extensive Unix/Linux knowledge • May take some Perl building skills • In short, you gotta know what you’re doing • … but even then, some modules Just Don’t Work
• 7.
  Case study • Building static Perl for Solaris • Minimal module list: DBI, DBD::Informix • Some dependencies as well • Using GCC 4.4 • Linking against native Informix CSDK • Bundling it all including environment startup into one fat Perl executable
• 8.
  Step 1: BuildApp::Staticperl • Default installation blows up in Solaris (make test fails) • Do forced make install • Manually edit ~/perl/bin/staticperl • Lots of small system specific changes • Try running “staticperl install”, see if it breaks • Make changes, try running, iterate
• 9.
  Step 2: installCPAN modules • staticperl instcpan DBI … • Some modules may fail at first • A dose of patience and some big wrench is required • Finally all tests should reasonably pass
• 10.
  Step 3: Customizingfor Informix • Add Informix configuration variables right there in staticperl • Most important: PATH, LD_LIBRARY_PATH • Linking against shared objects in known location • Utmost importance: LD_RUN_PATH (ld -R) • Prepare bootstrap.pl: set up Informix environment variables
• 11.
  Step 4: Customizingfor DBI • Prepare “bundle” file: take bundle.smallperl as an example (Remove first line “static”! Almost drove me mad!) • Add DBI, DBD::Gofer::*, DBD::Informix • Add perl5db.pl and Term::ReadLine for debugger (you’ll need it, trust me) • Add utf8, Encode, whatever
• 12.
  Step 5: Building •~/perl/bin/staticperl mkperl -v --boot bootstrap.pl gofer.bundle • -v to see if something goes wrong • --boot sets bootstrap script, it gets executed when static perl starts up • Don’t use “exit 0” in bootstrap, you’d be much surprised (remember perl5db.pl? Invaluable.)
• 13.
  Finita • Voila, we’ve got a statically built perl • One 5.5M executable file, no dependencies • All run time library paths are built in • Send it over to remote system and test • <Live demo here>
• 14.
  Questions? • I haveworking staticperl script for Solaris, with DBD::Informix built in • Not CPAN quality (ugh), so isn’t published • But if you’re curious, drop me a line: Alex Tokarev <tokarev@cpan.org>