Continuous
Deployment in Perl
Presentation by Alex Balhatchet (KAORU)
Intro
What is continuous deployment?


Commit Changes




                 Deploy Changes
                                  As quickly as
                                  possible! :-)

 Test Changes
Committing Changes

● Use your favourite VCS

● Push the changes somewhere centralized
  (staging/testing environment)

● This should kick off a "build and test" cycle if
  one is not currently running
Testing Changes

Perl is absolutely fantastic for testing.

● TAP

● TAP::Harness / App::Prove

● Test::Builder / Test::More
Deploying Changes

● Pick your favourite deployment method

● Make it as fast as possible

● Make it as easy as possible
Challenges

● Fast tests

● Reliable tests

● Fast deployment
Challenges

● Fast tests
                    Focus of this talk
● Reliable tests

● Fast deployment
Perl Testing
TAP::Harness
and App::Prove
TAP::Harness and App::Prove

/usr/bin/prove

     uses App::Prove

           uses TAP::Harness
App::Prove features - basics

● Run lots of tests with one command

● Hide non-failure output

● Run tests in parallel

● Show timing information
App::Prove features - basics

alex@karin$ prove -l -r -j 16 t/
t/00-load.t .......... ok
t/01-backup.t ........ ok
t/02-delete_files.t .. ok
All tests successful.
Files=3, Tests=51, 1 wallclock secs ( 0.06 usr
0.01 sys + 0.78 cusr 0.20 csys = 1.05 CPU)
Result: PASS
App::Prove features - advanced

● Load plugins from App::Prove::Plugin::*

● Save the TAP results to a .tgz archive

● Save state between runs and use that state
  to change the order for future runs
App::Prove features - advanced
alex@karin$ prove -l -r --state=hot,all,save t/
No saved state, selection will be empty
t/00-load.t .. ok
t/01-good.t .. ok
t/02-bad.t ... 1/1



alex@karin$ prove -l -r --state=hot,all,save t/
t/02-bad.t ... 1/1   <===== Runs first!
t/00-load.t .. ok
t/01-good.t .. ok
App::Prove features - advanced

Other "state" options:

● slow - very useful with -j N

● fresh - only run the tests you need to

● last - same as last run, even with --shuffle
Test::Aggregate
Test::Aggregate

● Combine multiple .t files into a single file

● Avoids compilation overhead

● Therefore speeds up your tests!
Test::Aggregate::Nested

● Alpha code

● Uses the fairly recently added syntax for
  subtests in TAP

● Works really well for us!
Test::Aggregate caveats

● Breaks BEGIN and END blocks

  (use Scope::Guard instead!)

● exit() is also a bad idea!

● Be aware of Test modules which use these

  (Test::NoWarnings is the most common!)
Parallelisation of Aggregated Tests
Currently closed source - sorry! The logic is:

   i. Split up tests into N groups

  ii. Copy .t files into temporary directory

  iii. Write temporary .t file that uses Test::
       Aggregate::Nested

 iv. Run those tests with prove -j N
TAP::Harness
::Archive
TAP::Harness::Archive

● "isa" TAP::Harness

● Stores the TAP output in a tar archive

● Gives you full TAP even when running in
  parallel

● Allows you to run your tests once and then
  format the results in multiple ways
How we format our TAP

● Process the output from our parallelised
  aggregated test runs

● Match up the failures with the .t files

● Write a summary in Markdown format that's
  later converted to HTML and emailed to us
How you might format your TAP

● TAP::Formatter::JUnit (eg. for Jenkins)

● TAP::Formatter::TeamCity

● TAP::Formatter::HTML
TAP::Formatter::HTML example
TAP::Formatter::HTML example
Putting it all
together
Continuous Deployment at Lokku

    svn commit                         On test success new code is
                                          automatically pushed

                                       Deployment is one command
                                             and very quick


   Perl daemon notices commit

Parallelised and aggregated test run
            starts running

Nicely formatted results are emailed
        on success or failure
What's next?
What's next?

● Test::WWW::Selenium::More

● Faster tests - more unit tests, fewer
  integration tests

● Parallelised deployment
Thanks!
Any questions?

Continuous testing and deployment in Perl (London.pm Technical Meeting October 2012)