How to use git fixup

Using git fixup helps you to speed up appending changes further back in the git history of your feature branch.


git commit --fixup aabbcc # Create a commit with the message "fixup! Commit message of aabbcc"
git rebase -i --autosquash master

It would be nice if you could use this feature without the -i flag, but until now it seems not to be possible. Read more about our recommended git workflow for feature branches.


How to update a single gem conservatively

The problem

Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:

bundle update cucumber-rails

... you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.

In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail...

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Updated: Five years of "Today I Learned" from Josh Branchaud

Added favorite TILs for Chrome, Git, and JavaScript. See bottom of that card.

Git: How to add changes matching a regular expression

When you have many changes, and you want to spread them across different commits, here is a way to stage all changes matching a given regular expression for a single commit.


Consider the following git diff output.

diff --git a/file1.rb b/file1.rb
index 806ca88..36d536b 100644
--- a/file1.rb
+++ b/file1.rb
@@ -1,7 +1,5 @@
-# Here is a useless comment.
-# It will be removed.
 class File1
-  def foo
+  def bar
     # ...
diff --git a/file2.rb b/file2.rb
index 550e1c6..600f4e3 100644
--- a/file2.rb
+++ b/file2...
Linked content

Five years of "Today I Learned" from Josh Branchaud

The linked GitHub repository is a bit like our "dev" cards deck, but groomed from a single person (Josh Branchaud). It includes an extensive list of over 900 TILs on many topics that might be interesting for most of us. (e.g. Ruby, Rails, Git, Unix..)


Here is an excerpt of all the Ruby TILs that were new to me. I encourage you to take your time to skim over the original list as well!

How to use Simplecov to find untested code in a Rails project with RSpec and Cucumber

Simplecov is a code coverage tool. This helps you to find out which parts of your application are not tested.

Integrating this in a rails project with rspec, cucumber and parallel_tests is easy.

  1. Add it to your Gemfile and bundle

    group :test do
      gem 'simplecov', require: false
  2. Add a .simplecov file in your project root:

    SimpleCov.start 'rails' do
      # any custom configs like groups and filters can be here at a central place



How to use a local gem in your Gemfile

You can use local copies of gems in your Gemfile like this:

gem 'spreewald', :path => '~/gems/spreewald'

As soon as you have bundled your project with the local copy of the gem, all code changes in the copy will be available on your project. So you can for example set a debugger or add console output in the gem and use it from your project.
If you checked out the gem with your versioning tool, you can easily reset your changes afterwards or make a pull request for the gem if you improved it.

Don't commit a Gemfile with local pat...

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Colorful output for several linux command line tools: grc

Because colors improve readability so much.
On Ubuntu 18.04 you can install it with sudo apt install grc

From github:

For the impatient - try following commands:

grc netstat
grc ping hostname
grc tail /var/log/syslog
grc ps aux

Rails: Rest API post-mortem analysis

This is a personal post-mortem analysis of a project that was mainly build to provide a REST API to mobile clients.

For the API backend we used the following components:

  • Active Model Serializer (AMS) to serializer our Active Record models to JSON.
  • JSON Schema to test the responses of our server.
  • SwaggerUI to document the API.

It worked

The concept worked really good. Here are two points that were extraordinary compared to normal Rails project with many UI components:

  • Having a Rails application, that has no UI components (only...
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Structuring Rails applications: the Modular Monorepo Monolith

Root Insurance runs their application as a monolithic Rails application – but they've modularized it inside its repository. Here is their approach in summary:


  • Keep all code in a single repository (monorepo)
  • Have a Rails Engine for each logical component instead of writing a single big Rails Application
  • Build database-independent components as gems
  • Thus: gems/ and engines/ directories instead of app/
  • Define a dependency graph of components. It should have few edges.
  • Gems and Engines can be extracted easier once nece...

Understanding SQL compatibility modes in MySQL and MariaDB

MySQL and MariaDB have an SQL mode setting which changes how MySQL behaves.

The SQL mode value is comprised of multiple flags like "STRICT_TRANS_TABLES, NO_ZERO_IN_DATE". Each flag activates or disables a particular behavior.

The default SQL mode varies widly between versions of MySQL and MariaDB. In general, more recent versions of MySQL and MariaDB have stricter settings than older versions, and MySQL has stricter settings than the more liberal MariaDB.

If your app explodes ...

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How to split up a git commit

Quick steps

  1. git rebase -i -> mark your commit with edit
  2. git reset HEAD~ (remove the marked commit, but keep its changes)
  3. Make several commits
  4. git rebase --continue

Detailed instructions

Basically, you will review the last n commits and stop at the splittable commit. Then you'll undo that commit and put its changes into new commits at your liking.

  1. Review commits (rebase)

    git rebase -i HEAD~3
    # or
    git rebase -i origin/master

    Git will give you a list of commits, younge...

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Automated "git bisect" will make your day

So you're hunting down a regression (or just a bug) and want to use git bisect to find out when it was introduced? Smart kid.
If you have a shell command ready to reveal if your current state is good or bad, you can have git do most of the work for you.

Using git bisect run <your command> you can tell git that your command will reveal the issue; git on the other hand will use the return value of that call to decide if the state is good or bad.

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How to view a file from another branch

Just run git show branch:file. Examples:

git show HEAD~:bin/command
git show origin/master:../lib/version.rb

Differences between transactions and locking

Web applications can be used by multiple users at the same time. A typical application server like Passenger has multiple worker processes for a single app. In a distributed deployment setup like we use at makandra you will even have multiple application servers, each with their own worker pool.

This means that your code needs to deal with concurrent data access. The two main tools we use to cope with concurrency are database transactions and distributed locks. These two are not interchangeable. You ca...

Geordi 2.7.0 released

  • Fixed #68: The "cucumber" command now fails early when @solo features fail.
  • Added: The "setup" command now prints the db adapter when prompting db credentials.
  • Fixed #71: When used without staged changes, the "commit" command will print a warning and create an empty commit. Any arguments to the command are forwarded to Git.
  • Fixed: The "commit" command will not print the extra message any more.
  • Added: The "commit" command prints a (progre...

Bookmarklet to generate a Pivotal Tracker story from Zammad Ticket

This is a bookmarklet you can add to Chrome or Firefox which will allow you to create a story in Pivotal Tracker from a Zammad ticket. This might come in handy when creating stories for SWAT Teams.

But first you will have to set two variables in the script below:

  • pt_project_id: the ID of the Pivotal Tracker Project you want to add stories to. This can be found as part of the URL of the project (<pt_project_id>)
  • pt_token: the Pivotal Tracker token used for authentication. Can be found in y...

How to bulk-unwatch many repositories on Github

To easily opt out of notifications for a large number of Github repositories, go to

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