Lessons Learned from PyMunich 2016

• SSL 2 and 3 are broken, so don’t use them,
• also don’t use TLS 1.0/1.1,
• get fresh certificate every 90 days,
• disable (make redirect) http because it can leak some information you don’t want.

There are many open source tools that can help you achieve nice and tidy encryption on your site. One of them is acme-tiny (https://github.com/diafygi/acme-tiny). It is very small script (less than 200 lines) which means you can easily read every line of the code which you should because you need to trust this tool with your private keys. The last talk I want to mention was by far my favourite one. Philip Bauer showed us how to debug like a pro (“Debug like a pro. How to become a better programmer through pdb-driven development”). His bread and butter tool is pdbpp or pdb++ which is a drop-in replacement for pdb. This means that you create break point just like with pdb but if you have pdb++ installed it will automatically get called instead. Here are the basic commands for pdb that Philip highlighted:

• l[ist] (list source code of current file)
• n[ext] (continue execution until next line)
• s[tep] (execute the current line, stop at the first possible occasion)
• r[eturn] (continue execution until the current function returns)
• c[ontinue] (continue execution, only stop when a breakpoint is encountered)
• w[here] (show stack trace, recent frame at bottom)
• u[p] (move up the stack)
• d[own] (move down the stack)
• b[reakpoint] (set a new breakpoint. tbreak for temporary break points)
• a[rgs] (print the argument list of the current function)

The nice thing about pdbpp is that it has a long list method (ll) which displays the whole function you are in (Note: ipdb also has long list method). Other python debugging tricks you should know about are:

• use ?for getting additional information lib/class/function/… (e.g. os?)
• use ??for displaying the source code of the lib/class/function you want to inspect (e.g. os.path.join??)
• pp(Pretty-print) is already in pdb so you should always use it
• pp locals()will pretty print local variables

One of the best tricks is the help function which accepts object and returns generated help page for the object. !help(obj.__class__)command will generate help page which will contain all the methods including class methods and static methods with docstrings, method resolution order, data descriptors, attributes, data and other attributes inherited and much more. Note: The reason you need to put ! before help function in pdbpp/ipdb is because is you don’t put ! you will call pdbpp/ipdb internal help function which is not the python build-in help function. You can also use --pdboption when running unit tests with pytest or nosetest and this will cause to drop in a pdb whenever a test fails or errors. From there you can write a code that will pass a test, copy paste that code into your file and you are done. This is the basic principle of Test-Driven / Debug-Driven Development (TDD). Any questions? Send us an email.