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CarrierWave: How to remove GIF animation

When accepting GIF images, you will also accept animated GIFs. Resizing them can be a time-consuming task and will block a Rails worker until the image is processed.

Save yourself that trouble, and simply tell ImageMagick to drop any frames but the first one.

Add the following to your uploader class:

process :remove_animation


def remove_animation
  if content_type == 'image/gif'
    manipulate! { |image| image.collapse! }

You may also define that process for specific versions only (e....

Migrate gem tests from Travis CI to Github Actions with gemika

We currently test most of our gems on Travis CI, but want to migrate those tests to Github Actions. This is a step-by-step guide on how to do this.

Note that this guide requires the gem to use gemika.

  1. Go to a new "ci" branch:
    git checkout -b ci
  2. Update gemika to version >= 0.5.0 in all your Gemfiles.
  3. Have gemika generate a Github Actions workflow definition by running
    mkdir -p .github/workflows; bundle exec rake gemika:generate_github_actions_workflow > .github/workf...

How to downgrade Google Chrome in Ubuntu

If you're experiencing problems with your Google Chrome installation after an update, it might help downgrading Chrome to check if the problem disappears. Keep in mind though that running outdated software, especially web browsers, is in most cases not a good idea. Please verify periodically if you still need to run the old version or if an even more recently updated version fixes the problems introduced in your version.

Here's how to get old versions of Chrome for your Ubuntu installation:

First, go to [UbuntuUpdates](https://www.ubuntuup...

Installing old versions of mysql2 on Ubuntu 20.04+

On some of our older projects, we use the mysql2 gem. Unfortunately, versions 0.2.x (required for Rails 2.3) and versions 0.3.x (required for Rails 3.2) can no longer be installed on Ubuntu 20.04. Trying this either leads to errors when compiling the native extension, or a segfaults when using it.

For Rails 4.2, mysql2 version 0.4.10 seems to work okay. If you still have issues, upgrade to 0.5.x, which should be compatible.

To install it, you have to switch the mysql2 gem to our fork. In your Gemfile, ...


Debugging SPF records

While debugging a SPF record I found spf-record.de to be very helpful.

  • it lists all IPs that are covered by the SPF record
  • shows syntax errors
  • helps you debugging errors like DNS lookup limit reached
  • it also lets you test a new SPF strings before applying it. This can save you time as you don't have to loop with operations

Also the advanced check at vamsoft.com has a very good interface to test new SPF policies.

Installing Ruby <= 2.3 on Ubuntu 20.04+

Installing old Rubies (<= 2.3) with a standard rbenv + ruby-build is no longer possible on Ubuntu 20.04. This is because those Rubies depend on OpenSSL 1.0 which is no longer shipped with current Ubuntus.

We have forked ruby-build with a workaround that makes it compile and statically link the latest OpenSSL 1.0 version. This works on Ubuntu 20.04, as well as on Ubuntu 18.04.

To switch to our fork of ruby-build, update ruby-build like this

git -C ~/.rbenv/plugins/ruby-build remote add makandra...

RSpec: run a single spec (Example or ExampleGroup)

RSpec allows you to mark a single Example/ExampleGroup so that only this will be run. This is very useful when using a test runner like guard.

Add the following config to spec/spec_helper.rb:

RSpec.configure do |config|
  # These two settings work together to allow you to limit a spec run
  # to individual examples or groups you care about by tagging them with
  # `:focus` metadata. When nothing is tagged with `:focus`, all examples
  # get run.
  config.filter_run_including :focus => true

How to fill in multiple lines in a textarea with cucumber

If you want to fill in textareas with multiple lines of text (containing line breaks) you can use Cucumber's docstrings:

And I fill in "Comment" with:

This is a long comment.
With multiple lines.

And paragraphs.

The step definition is part of the spreewald gem

VCR: Alternative way of mocking remote APIs

If you need to test interaction with a remote API, check out the VCR gem as an alternative to Webmock or stubbing hell.

The idea behind VCR is that is performs real HTTP requests and logs the interaction in a .yml file. When you run the test again, requests and responses are stubbed from the log and the test can run offline.

It's a great way to mock network requests to an external service without going through the pain of logg...

Linked contentAuto-destruct in 11 days

Updated: Showing a custom maintenance page while deploying

Added a section "manual mode" in case you don't have capistrano 2.

Auto-destruct in 13 days

assignable_values 0.16.2 released

assignable_values now does not load scopes to memory during validation any more.

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Geordi 4.2.0 released

We released a new version of our gem geordi

4.2.0 2020-10-02

Compatible changes

  • Add auto_update_chromedriver as global setting option to automatically update chromedriver before cucumber
    tests, if Chrome and chromedriver versions don't match.
  • Dump command: Add support for multiple databases
  • Add Ruby 2.7 to list of supported Ruby versions
  • Fix #115: geordi cucumber --modified command, that corrupted filenames like:
    No such file or directory tures/pages.feature
  • Avoi...
Auto-destruct in 7 days

Spreewald 2.9, 2.99 and 3.0.0 released

Versions 2.9.0, 2.99.0 and 3.0.0 of our gem Spreewald have been released.

2.9.0: Rework email steps

  • The step an email should have been sent with: does now support wildcards (* at the end of a line to ignore the rest of the line, * as single character in a line to ignore multiple lines). The step also has better error messages if an email could not be found.
  • The step show me the emails got an option to display only the email headers. Additionally, a new step `show me the email( header)?s...

PostgreSQL: Importing dumps created with newer versions

When importing a dump created on a server that has a more recent pg_dump version you might get an error like

$ geordi dump staging -l
# Sourcing dump into the project_development db
pg_restore: [archiver] unsupported version (1.14) in file header
x An error occured loading staging.dump

On my machine I had psql version 10.14 which was the most recent package from the standard repository. The server, however, had pg_dump version 12.4.

The issue could be fixed by [installing postgres 12 from the PostgreSQL APT-Repositories]...

Rails: How to restore a postgres dump from the past

It sometimes happen that a database dump, that would want to insert into your development database, does not match the current schema of the database. This often happens when you have an old dump, but your current setup is up to date with the the master.

Hint: In most cases it is sufficient to delete and recreate the local database in order to import the dump. If any problems occur, proceed as follows:

1. Figure out the original migration status of the dumpfile

  • Convert your dump to plaintext: `pg_restore -f some.dump > some.dump....

Keeping web applications fast

Our applications not only need to be functional, they need to be fast.

But, to quote Donald Knuth,

premature optimization is the root of all evil (or at least most of it) in programming

The reasoning is that you should not waste your time optimizing code where it does not even matter. However, I believe there are some kinds of optimizations you should do right away, because

  • they are either obvious and easy
  • or they are very hard to do optimize later

This is an attempt to list some of those things:

On the server



Cucumber step to match table rows with Capybara

These steps are now part of Spreewald.

This note describes a Cucumber step that lets you write this:

Then I should see a table with the following rows:
  | Bruce Wayne       | Employee    | 1972 |
  | Harleen Quinzel   | HR          | 1982 |
  | Alfred Pennyworth | Engineering | 1943 |

If there are additional columns or rows in the table that are not explicitely expected, the step won't complain. It does however expect the rows to be ordered as stat...

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