Matt Chung's Site

Author: mattchung

  • Putting your mentor on a pedestal

    Presenting at DevOps London ExchangeLast night, I presented (deckslide here) on AWS Lambda at DevOps London Exchange. I really enjoy public speaking, but it wasn’t always that way.

    In fact, I used to hate it – feared it.

    I vividly remember an embarassing instance in high school Spanish. My classmate and I had to do a presentation. I got up, and stood in front of the class for 20 minutes.

    That’s it. I just stood there. I didn’t say a SINGLE word the entire time.

    Fast forward to college. By this time, I really needed help with public speaking. My uncle suggested joining Toastmasters.

    I visited a few clubs and I wasn’t very impressed. But then, I discovered Sherman Oaks Toastmasters.

    I met Peter Bunce. He was very passionate about Toastmasters. He was very discplined. For 20 years, he rarely (if ever) missed the weekly meetings. His entire life was devoted developing the Toastmasters club.

    We used to get coffee and dinner. He assigned himself as my mentor. Honestly, I was hoping for someone else. He was tooeccentric. He didn’t encapsulate all the characteristics of my ideal rolemodel.

    Setting the right expectations

    I’ve always had unreal expectations from those who I looked up to. Peter was no exception. Him being a great speaker wasn’t enough for me. I had unrealistic expectations of what one mentor can offer – let alone any person.

    “If you should end up with a teacher who doesn’t seem right for you, first look inside.”

    —George Leonard

    A note to my mentor

    I sent Peter a message on Facebook this morning. But he’ll never read it.

    Peter Bunce passed away a few weeks ago. I wish that I had reached out to him sooner.

    If there’s someone who mentored you, be it informally or formally, or touched your life in some way, don’t wait to tell them that they moved you. Take a moment to reach out to them, to say thank you.

  • SpeedCurve Library: Travis CI + coverage + tox

    I’m writing a python library (speedcurve.py). At work, we’re using SpeedCurve to track our web performance. SpeedCurve’schangelog reveals can trigger a deployment (and a series of tests). I’m replacing our curl+ansible commands with this. I plan on integrating this with slack as well.

    This project is heavily influenced by github3.py. I’ve been contributing frequently (plan on continuing to) and find it elegant. You’ll notice A LOT of similarities.

    For this project, I want the following up front:
    • Proper Documentation
    • 100% test coverage and flake8 checks
    • Integration with Travis CI

    This post focuses on configuring tox to execute coverage.

    Configure tox + coverage

    Since tox does NOT play nicely with pipes (|), this simple shell scripts checks for 100% test coverage:

    #!/bin/sh

coverage run --source speedcurve -m py.test
coverage report | tail -n 1 | grep '^TOTAL.*100%$'

    This goes in tox.ini

    [testenv:coverage]
commands =
    ./coverage-check.sh

  • Implementing Licenses API for github3.py

    I came across this license issue while searching on GitHub. So, I thought I’d give it a shot. I pinged sigmavirus24 in #github3.py seeing if this was a feature I could implement. He gave the thumbs up and I was off.

    Testing manually first

    Before any implementation, I always like to get a better understanding of the API by using good ol’ fashion curl.

    curl https://api.github.com/licenses \
-H "Accept: application/vnd.github.drax-preview+json"

    Sending a custom Accept: Header

    In the code base, most classes inherit from github3.GitHubCore, which inherits from requests.Session. We can pass in**kwargs, and requests.Session.get accepts a headers as a kwarg. So, we can pass a custom Accept: header like so:

    headers = {
    'Accepts': 'application/vnd.github.drax-preview+json'
}

url = self._build_url('license')
json = self._json(self._get(url, headers=headers))

    How to add attributes to License model

    By default, the model will not expose any attributes. How do we do that? The key is implementing __update_attributesmethod.

    github3.licenses.License inherits from github3.models.GitHubObject, which calls __update_attriubtes in its__init__.

    class GitHubObject(object):
    """The :class:`GitHubObject <GitHubObject>` object. A basic class to be
    subclassed by GitHubCore and other classes that would otherwise subclass
    object."""
    def __init__(self, json):
        super(GitHubObject, self).__init__()
        if json is not None:
            self.etag = json.pop('ETag', None)
            self.last_modified = json.pop('Last-Modified', None)
            self._uniq = json.get('url', None)
        self._json_data = json
        self._update_attributes(json)

    So, let’s add License attributes

    def _update_attributes(self, license):
    self.name = license.get('name')
    self.permitted = license.get('permitted')
    self.category = license.get('category')
    self.forbidden = license.get('forbidden')
    self.featured = license.get('featured')
    self.html_url = license.get('html_url')
    self.body = license.get('body')
    self.key = license.get('key')
    self.description = license.get('description')
    self.implementation = license.get('implementation')
    self.required = license.get('required')

    Writing test

    This guide is a great place to start. But, just a few pointers. For unit tests, copy/paste example data the API docs. For example, grab the JSON data from the license documentation. Save it under tests/unit/.

    For integration tests, you’ll need to perform HTTP request(s). The betamax wrapper will record it to tests/cassettes.

    Summary

    This feature was merged in this pull request. I really enjoy contributing to this project. Primarily since sigmavirus24 is a pleasure to work with and extremely helpful. He’s super patient and I appreciate he takes the time onboarding new contributors.

  • Contributing to github3.py

    sigmavirus24 tweetI’ve always been scared of open sourcing, despite wanting to get involved for a long time? Why?

    For a long time, I’ve programmed in isolation. But, I did enjoy it. Unfortunately, this leaves little (to none) opportunity for feedback and critism. Afraid of rejection? Afraid of not appearing as smart as I think I am ?

    Serepdentiosuly, I came across this post on reddit post. His comment looked warm and welcoming. Let’s give it a shot again.

    I received an e-mail from @sigmavirus24. Looks like he could use some help moving existings tests under tests/* to tests/unit and tests/integration. This is a great way to get familiar with the code base. I’m game.

    @sigmavirus24 posted this tweet. I was so happy and I hugged Jessica, who was sitting next to me when I saw it pop up on my feed. I didn’t anticipate it and it is what makes me enjoy working on F/OSS.

    I Was on IRC and dropped a note to @sigmavirus24 about implementing this new API feature. I think I’ll tackle this in parallel with migrating tests over.

  • Mocking boto exception

    I was getting so frustrated.

    I knew how to raise the exception with side_effect=. But, how do you mock the exception?

    try:
    connection = connect_to_sqs
except BotoServerError as m:
    if m.error_code == "AlreadyExistsException"

    To get it to work, I inherited the exception class – BotoServerError

    from boto.exceptions import BotoServerError

class MockBotoServerError(BotoServerError):
    def __init__(self, error_code)
        self.error_code = error_code

@mock.patch('cloudwhale.build.connect_to_sqs', side_effect=MockBotoServerError())

    Order of decorator

    Also, pay attention to the order of parameters. My assertions were failing left and right.