Оvercommit - convenient Git hook manager

Voldemar Duletskiy, Ruby developer, Evrone, Moscow Ruby Meet-up 6 report
01 August 2017   1615

Dynamic, open source programming language with a focus on simplicity and productivity, it has an elegant syntax that is natural to read and easy to write.

Hello Ruby fans! Today we will talk about Overcommit - the convenient management of git-hooks.

Imagine that you have a small project with a micro-team of three or four people, including the manager. Deadline is near, but you cannot lower the quality of the code. You don't wanna use CI and there are no extra money for it.

What is hooks and where are they located?

It is the scripts that are executed at certain event. You can view all existing hooks by running the following command:

ls -la .git/hooks

You will see this listing:

-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 commit-msg
-rwxr-xr-x   1 voldemar  staff  3755 28 июн 16:39 overcommit-hook
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 post-checkout
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 post-commit
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 post-merge
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 post-rewrite
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 pre-commit
-rwxr-xr-x   1 voldemar  staff   673  2 Jun 14:37 pre-commit.sh
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 pre-push
-rwxr-xr-x   1 voldemar  staff  3755 28 Jun 16:39 pre-rebase

Hook is an executable file, which can content anything, including the Ruby code.

Why it is cool?

  • You can put linters like rubocop to the pre-commit hooks. It will not allow you to commit substandard code
  • You can hang up rspec to the pre-push hooks, and if the tests are dropped - cancel code sending
  • If you are already actively using hooks - you don't need to drag them from one repository to another, they all lie in .ovecommit.yml in a convenient format

Ruby static code analyzer, based on the community Ruby style guide

If you suffer from dispersion and you are sick of messages from your CI that tests have dropped again, or the ruby-cop found a million syntactic violations (or your colleagues in the code-review process). If you are an experienced developer, a good set of hooks seriously discourages young developers and reduces your code-review time. 



gem 'overcommit'

Execude from the consol:

bundle exec overcommit --install

 Now let's edit .overcommit.yml file

    enabled: true
    command: ['bin/bundle', 'exec', 'rubocop', '-R']
    on_warn: fail
    enabled: true
    command: ['bin/bundle', 'exec', 'haml-lint', 'app/views/']
    on_warn: fail
    enabled: true
    command: ['bin/bundle', 'exec', 'scss-lint']
    include: 'app/assets/**/*.scss'
    on_warn: fail

    enabled: true

We can see here that the launch of the rubocop scripts is describled in nice forman. haml-linter, sccs-linter and tests runs just before the commit.

In order to enforce hook running this should be executed:

bundle exec overcommit -R

Now, with every attempt to commit something, checks will be performed firstly.


Underwater rocks

If there are a lot of tests or they are dropping randomly - if you already have a habit to brew coffee while test runs, it's better to chop the hook responsible for running the tests. If they fall randomly - fix the tests at last, damn it.

Integration with Rubymine - I have serious problems with the integration of Overcommit and Rubymine

Continuous Integration

The practice of merging all developer working copies to a shared mainline several times a day

Overcommit and CI integration - if you still decide to connect CI, then most likely it already provides validation for the code. Often, their rules don't match and you have to adjust the settings, for example Rubocop under CI, or vice versa.

You can skip hooks by running git commit --no-verify


Overcommit is an excellent utility for maintaining a project in good shape for small teams. It will allow you not to grab your head every time after creating a pool of the requester with exclamations "Damn, I forgot to use rubocop again!" or "Damn, all the tests fell!".

Ruby Meditation #22 in Dnipro

Meditation will be held on May 19, at Parle, Troitska St, 21 g, Dnipro
27 April 2018   546

On Ruby Meditation #22 you will hear about helpful tools and gems for building Slack apps, examples how to build functional architecture with ruby, which place takes Ruby on Rails among alternatives in 2018 and much more.

Come and get your portion of good mood, knowledge, professional communication and tasty lunch :)

Share your positive experience and best practices on this Ruby Meditation #22. If you have any work issues you cannot solve, our community will gladly help you to find the best way out in live discussion at Lightning talks session. You may also try yourself as a speaker with a short 5-10 mins talk. Fill in this form.


Anna Shcherbinina

Topic: "Docker + GPU. Not about mining."

Anna Shcherbinina
Anna Shcherbinina

Just before Christmas we launched a new body-measurement feature for our shapify.me project. A person goes into the 3D booth, gets scanned, and the body-measurements are calculated with the 3D scan data. We couldn't avoid using a GPU with these calculations.

How to install this branch of processing into our elegant scaling pipeline? When you're dealing with 3D scans you should remember two things: it's expensive and time-consuming. By the way, its workload fluctuates throughout the days. The easiest solution for us was to use Docker.

This speech is not about mining, but the most helpful articles for us were ones such as "Building your own mining farm". That's because we use quite a similar infrastructure.

GPU, Docker, scaling. What we achieved, where we failed, and what it became of it in the end is all included in my speech.

Anna Shcherbinina

Head of Web, Artec3D, Luxembourg

Kirill Shevchenko

Topic: "Building Slack apps with Ruby."

Kirill Shevchenko
Kirill Shevchenko

Overview of Slack APIs. Their features, restrictions, and bottlenecks. Which API is right for you? Helpful tools and gems for building Slack apps.

Kirill Shevchenko

Ruby/JS Developer

Valentine Ostakh

Topic: "Functional objects in Ruby: new horizons "

Valentine Ostakh
Valentine Ostakh

Overview of functional programming concepts.  What is functional objects. Examples how to build functional architecture with ruby.

Valentine Ostakh

Ruby/JS Developer

Leonid Shevtsov

Topic: "A polyglot's view of Ruby on Rails"

Leonid Shevtsov
Leonid Shevtsov

Nowadays, it's hip to switch from Rails to other languages and frameworks. Leonid, too, has abandoned Rails, played the field a bit, and has come around to occasionally but consistently picking Rails for some projects. What's the modern reason to use Rails? What are the strengths of Ruby and Rails and how to build upon them? When you should really jump to some other platform? Let's answer these questions in a true Ruby meditation.

Leonid Shevtsov

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Oleksii Dashkevych

Topic: "Project development - preparing hell dish together"

Oleksii Dashkevych
Oleksii Dashkevych

The recipe is averaged, because of many variations. We take some Ruby code and add Rails magic, Postgresql on top. Add Docker for viscosity. Then put this on AWS EBS pan and start frying. It's all roasted until burning deadlines and generously watered with bugs, serves to the customer. They start eating. Eat and whisper: “This is an awesome product!”. At the same time, he forehead is sweating. Kindly offer to fix bugs, but we refuse and put them in JIRA. Do I need to talk about what kind of feedback comes then? Tasks with such recipes, that double estimated.

Oleksii Dashkevych

Ruby/JS Developer

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