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Debugging ansible modules

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Debugging (custom) Ansible Modules -- Presentation from Ansible meetup in London on 16th July 2015

Published in: Technology

Debugging ansible modules

  1. 1. Debugging custom Ansible modules
  2. 2. Who am I Alex Leonhardt Ansible user for ~2-3 months, previously Puppet and some SaltStack Ops guy for a very long time Twitter: @alex_leonhardt
  3. 3. Elsevier "Elsevier is an information solutions company with roots in publishing scientific, medical, and technical literature" Publisher of scientific, medical and technical literature ScienceDirect.com, part of Elsevier AWS, Ansible, Packer Python / BASH + GoCD for operations/automation Microservice architecutre (mostly Java) Know any/all of above? We're hiring!
  4. 4. Debugging Ansible modules Ansible makes debugging somewhat problematic, expects valid json for any output. print('x has value: {0}').format(x) won't ever make it to the console. So how do we check the state of a variable, e.g. when looping over a list?
  5. 5. Structure
  6. 6. Playbook
  7. 7. Be verbose, be very verbose -vvv
  8. 8. Using AWS (who isn't) ? ~/.boto Boto has a debug setting, use it!
  9. 9. Boto debug HTTP POST output Caution! Credentials are shown in clear text
  10. 10. Custom module ec2_describe.py
  11. 11. Custom module ec2_describe.py
  12. 12. Custom module list ec2 instance ids but 'print' won't work >:(
  13. 13. Custom module (run)
  14. 14. Custom module (run)
  15. 15. Some output not great, but something
  16. 16. at least we now know the correct class Some more output to check for attributes, etc.
  17. 17. IDEs really help to find the correct VIM vs IDE vs (other) class(es) quickly, but use whatever you like
  18. 18. Fixed code and the correct method used ... this time ;)
  19. 19. Final play
  20. 20. Final play (output)
  21. 21. But wait... ... what about print("hello world: {0}").format(x) ?
  22. 22. Use python logging " p r i n t "
  23. 23. Use python logging Setup logging in the main() function CAUTION! Thiswillalsoprintbotodebugoutputincludingyourplain-textkeys!
  24. 24. Finally.. we get some output!
  25. 25. Bonus points - more boto debug!
  26. 26. Use 'q' "Quick-and-dirty debugging output for tired programmers" Install it with pip install q( ) Output is sent to $TMPDIR/q Use for normal output (replace 'print' with 'q') Use as a decorator (@q) https://pypi.python.org/pypi/q
  27. 27. A q(uick) example Output Decorator
  28. 28. A q(uick) example (output) Output
  29. 29. A q(uick) example (output) Decorator
  30. 30. check out the temporary directory: Mooaaarr debugging! tell ansible to not clean-up after itself: $exportANSIBLE_KEEP_REMOTE_FILES=1 $play-Mmodules/-iinventorymyplay_describe.yml-vvv (in our case locally as we dont run against remote hosts) $cd ~/.ansible/tmp/ansible-tmp-1434809169.56-151563844546363 $ls-l -rw-r--r-- 1ale staff 7265520Jun15:06ec2_describe
  31. 31. Mooaaarr debugging! ec2_describe [...] state=module.params.get('state') ifstate=='describe':     i_list,changed=get_instance_list(module,ec2) else:     changed=False     i_list='Failed' module.exit_json(changed=changed,instances=i_list) #importmodulesnippets #ThiscodeispartofAnsible,butisanindependentcomponent. #Thisparticularfilesnippet,andthisfilesnippetonly,isBSDlicensed. [...] #==BEGINDYNAMICALLYINSERTEDCODE== ANSIBLE_VERSION='1.9.1' MODULE_ARGS='region=eu-west-1' MODULE_COMPLEX_ARGS='{"region":"eu-west-1"}'
  32. 32. Use pdb (python debugger) ... to step through the code. ~/.ansible/tmp/ansible-tmp-1434809169.56-151563844546363$ python-mpdbec2_describe
  33. 33. Cleanup after yourself Leaving debug logs around is dangerous, so don't forget! rm-vf/tmp/ansible_debug.log$TMPDIR/q
  34. 34. Links / Resources https://docs.python.org/2/library/logging.html https://pypi.python.org/pypi/q https://docs.python.org/2/library/pdb.html http://docs.ansible.com/ec2_module.html http://docs.ansible.com/developing_modules.html#testing-modules
  35. 35. Thank you!

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