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

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

  1. 1. Proxying DBI with DBD::Gofer and App::Staticperl San Diego.pm talk May 17, 2012
  2. 2. Environment• Need to connect 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. 3. Solution: DBD::Gofer• Stateless DBI 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. 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. 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. 6. App::Staticperl gotchas• Not very 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. 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. 8. Step 1: Build App::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. 9. Step 2: install CPAN 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. 10. Step 3: Customizing for 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. 11. Step 4: Customizing for 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. 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. 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. 14. Questions?• I have working 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>

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