Computers, Open-source, Software

Assign Pull Requests with Hubot

ChatOps was a term our DevOps person shared with me. Its the concept of automating everything you can through your company chat client. This could include monitoring, deploying, and just having fun (/pugbomb anyone?)

We implemented a pull request policy for all new code going to master. A pull request is opened by a developer on Github for the feature branch they want to merge into master. One of the biggest benefits to opening a pull request is having a peer review happen on your code where at least one other developer provides a review before it is committed to master. Fixing issues in the code at this point in the development cycle is relatively inexpensive compared to having this code fail QA, or BA sign off, or worst case, having a production incident.

Who reviews the pull requests? In the interest of being fair, it shouldn’t be a single developer that carries that burden. Pull requests can be a fantastic tool for transferring technical and domain knowledge so its best if everyone can participate. A developer might have never had occasion to work on the part of the codebase that contains the changes. For these reasons, we decided to do a round robin assignment of PRs to the developers. And yes, we fixed the bug where you get assigned your own PR 🙂

To accomplish this we utilized an open source project called Hubot that is maintained by Github and has integrations with Slack, as well as other chat clients. Hubot scripts are written in CoffeeScript, and the platform runs on Node.js. We enabled the integration between Github and Slack. A chat bot will publish a message on Slack when a pull request is opened. Hubot listens for these messages and then runs the code that you specify in response to the event. It sounds complex, but most of the heavy lifting is already done for you. You just listen for keywords, and take certain actions.

In our case, mentioning to a developer that he or she is assigned (via Slack) to a PR was sufficient for our use case. We created a new Slack channel, setup a webhook, and write a few lines of CoffeeScript to do the round robin assignment. It looks like this in Slack:

Screen Shot 2016-08-11 at 6.30.50 PM

HubotSlack = require 'hubot-slack'

module.exports = (robot) ->

Require the hubot-slack module. Inside this function is where we will do our work

# { <github username>: <slack username> }
 assignees =
 'bsimpson': 'ben.simpson'

getAssignee = ->
 index = robot.brain.get('assignee_index') || 0
 assignee_key = Object.keys(assignees)[index]
 assignee = assignees[assignee_key]

 if index >= Object.keys(assignees).length-1
  index = 0

 robot.brain.set('assignee_index', index)

We list our assignees in an hash and then use robot.brain to store where we left off. This allows us to restart our client without losing our place in the round robin assignment. You will notice that the assignment hash has two usernames to allow mapping from Slack to Github user accounts in the event they are different.

regex = /Pull request submitted:.* by (.*)/i

robot.listeners.push new HubotSlack.SlackBotListener robot, regex, (msg) ->
 author = msg.match[1]
 assignee = getAssignee()
 until (assignee != assignees[author])
 assignee = getAssignee()

 msg.send "<@#{assignee}> you've been assigned to #{author}'s pull request."

This is the binding we make to listen to Github bot messages. We can’t use robot.listen since this only works for human messages. Since we are talking bot to bot, we have to utilize the SlackBotListener.

Now that we have our code in place, we can create a new Slack webhook. Inside your Slack settings click “Apps and Integrations” > “Manage” > “Incoming Webhooks”. Add a new one for the channel you want Hubot to post to and get the token. This will be needed when we start Hubot.

HUBOT_SLACK_EXIT_ON_DISCONNECT=true HUBOT_SLACK_TOKEN=xxxxxxx./bin/hubot --adapter slack & echo $! > /path/to/hubot/

This will install any dependencies and run Hubot. Substitute your token from earlier for the HUBOT_SLACK_TOKEN. The pid tracking is important if you are using Monitrc to monitor your process.

Happy ChatOps-ing!


Computers, Open-source, Web

Configurable Javascript In Place Editor

Why do we need another in place edit library for Javascript? This one is different of course! This library allows for a high degree of customization due to its modular nature. Each action on an in place edit object (submitting on blur, adding a class on focus, toggling a label on click, etc) is complete isolated and designed to stack with each other. This allows for one library to accomplish a wide variety of in place edit functionality in the same project. You can even have different functionality on the same page if you wish.

Setup is a breeze. Just grab the latest copy of the Javascript library from You will need to be using jQuery in your project, since this plugin depends on it to work. Once you have include both jQuery, and in_place_edit.js, you can initialize it like this:

  $(function() {

The argument passed is the CSS selector that contains the form on which you wish to use in place edit.

Next, we need to configure the form to tell it what actions we want it to perform. If we want basic edit in place functionality, we can add “submit_on_blur” to have the form submit when a blur event is received. Note that this only occurs if the contents of the form have changed, in order to save on the number of server posts.

<div class="in_place_edit" data-in_place_data="submit_on_blur">
  <form action="#" method="post">
    <input type="text" name="foo" value="foo" />

The options are simple, and the combination are many. Check out the following options to see what you can do with your form fields on the DEMO page.

Happy in place editing!

Update: This plugin has been updated to be a jQuery plugin. Thanks to jsumners for providing lots of help!

Linux, Open-source, Ruby, Software

Rail’s Acts_as_revisable now summarizes changes

If you are a frequent reader, please congratulate me next time you see me on my first ever GiHub commit. I have been a long time user of GitHub, but I haven’t contributed anything back yet. I decided to start with the project acts_as_revisable, because I have some ideas for it that I think are useful.

The commit tonight adds a “revisable_changes” column, which records the attributes “before” and “after” values in the revision record. This data is calculated from the ActiveRecord instance method “changes”. To demonstrate:

# User.create :username => 'ben'
#[nil, "ben"]}>
# User.find(1).update_attributes :username => 'bob'
#["ben", "bob"]}>

This should serve as a good base to build summaries in a human readable format in an application. After tossing around a few different word choices to describe the changes, I decided that the better approach was to just record the data that changed in a structured format and leave it up to the implementation. Such an implementation may look something like this:

  def changes_summary do |attribute, values|
      before, after = values[0], values[1]
      if before.blank? and after
        "Added #{attribute} as #{after}"
      elsif before and after.blank?
        "Removed #{attribute} value of #{before}"
        "Changed #{attribute} from #{before} to #{after}"
    end.join('; ')

Using our user instance above, this method out return: “Changed username from ben to bob”.

Other plans for acts_as_revisable in the future include tracking associations of a model. For example, if a user has many permissions, and the permissions change, the revisable information will include the permissions for that user at that point in time. I haven’t worked out the specifics of this yet, as it could potentially generate a lot of unwanted data. I plan on parsing the data from ActiveRecord’s “reflect_on_all_associations” method to gather the associations. I will then provide a way for a user to configure which associations should, or should not be tracked. Then I will iterate through these objects using ActiveRecord hooks and somehow record the state. Either a shadow table, or by serializing the associations in a column. The trick here will be to marshal the objects back to the live data when a revert is called. More soon…