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...

If you use a newer SSH key generated with the ED25519 algorithm instead of RSA (see Create a new SSH key pair), the deployment with Capistrano may fail with the following message:

The deploy has failed with an error: unsupported key type `ssh-ed25519'
net-ssh requires the following gems for ed25519 support:
 * ed25519 (>= 1.2, < 2.0)
 * bcrypt_pbkdf (>= 1.0, < 2.0)
See https://github.com/net-ssh/net-ssh/issues/565 for more information
Gem::LoadError : "ed25519 i...

Building application assets with esbuild is the new way to do it, and it's great, especially in combination with Sprockets (or Propshaft on Rails 7).
You might be missing some convenience features, though.

Here we cover one specific issue:
Once you have started your development Rails server and esbuild with the --watch option (if you used jsbundling-rails to set up, you probably use bin/dev), esbuild will recompile your assets upon change, but build errors will only be printed to the terminal. Your application won't complain about them ...

Geordi 1.0 features a command line application geordi, that holds most of Geordi's previous commands.

New features

• command help and usage examples right within geordi (geordi help and geordi help <command>)

• quick command access: type just the first few letters of a command, e.g. geordi rs or geordi dev[server]

• command dependencies, e.g. geordi rspec invokes geordi bundle-install (which bundles only if needed)

• no cluttered /usr/bin, but all commands in one handy tool

• template for easily adding new...

Instead of using this hack you might want to use MariaDB 10.x which can work with both old and new apps.

An alternative could be to use the MySQL Docker image which is still updated for 5.6.

Ubuntu 16.04 only provides packages for MySQL 5.7 which has a range of backwards compatibility issues with code written against older MySQL versions.

Oracle maintains a list of official APT repositories for MySQL 5.6, but those repositories do...

This is an awesome gadget in your toolbox, even if your test coverage is great.

• gem install ruby-debug (Ruby 1.8) or gem install debugger (Ruby 1.9)
• Start your server with script/server --debugger
• Set a breakpoint by invoking debugger anywhere in your code
• Open your application in the browser and run the code path that crosses the breakpoint
• Once you reach the breakpoint, the page loading will seem to "hang".
• Switch to the shell you started the server with. That shell will be running an irb session where you can step thr...

TL;DR: Update the 'net-ssh' gem by adding to your Gemfile:

gem 'net-ssh', '=2.9.1'

Now run bundle update net-ssh. It has no dependencies so it shouldn't update other gems.

If you're using Ruby 1.8.7 and want to update net-ssh to a version > 2.9.1 you also need to add this to your gemfile:

gem 'backports', :require => false

... and in your deploy.rb add this:

require 'backports/1.9.2/array/select' 

Background

You propably have an older version of Capistrano and thereby an older version of `n...

If your Webpack build is slow, you can use the Speed Measure Plugin for Webpack to figure out where time is being spent.
Note that at time of writing, Webpack 5 seems unsupported. It works on Webpack 4, though.

Wire it into your application as described in the library's documentation:

1. Hook into your environment file, e.g. config/webpack/development.js and instead of exporting your Webpack config,...

When making cross-domain AJAX requests with jQuery (using CORS or xdomain or similar), you will run into issues with HTTP headers:

• jQuery will not set the X-Requested-With header. On your server, requests will not look like AJAX requests (request.xhr? will be false).
• jquery-ujs will not set CSRF headers.

This is by design and improves secu...

If your requests blow up in Ruby or CURL, the server you're connecting to might only support requests with older SSL/TLS versions.

You might get an error like: OpenSSL::SSL::SSLError: SSL_connect SYSCALL returned=5 errno=0 state=unknown state

SSL Server Test

This SSL Server Test can help finding out which SSL/TLS versions the server can handle.

Ruby

In Ruby, you can teach Net::HTTP to use a specific SSL/TLS version.

uri = URI.parse(url)

ssl_options = {
   use_ssl: true,
   ssl_version...

Web forms can be made much more usable with a few HTML attributes. Short summary:

• type: Tells browsers about the input data type. Mobile browsers will select a virtual keyboard based on this value. Some browsers will add simple validation, e.g. for type email.
• inputmode: Direct hint about the virtual keyboard to use. Inferred from type, but can be very handy when ...

If you get one of this errors:

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: (<unknown>): found character that cannot start any token while scanning for the next token at line 1297 column 3
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: undefined method `empty?' for nil:NilClass at /etc/puppet/environments/production/manifests/nodes.pp:1 on node example.makandra.de
Warning: ...

When your site is mapped into the URL-space of another server using mod_proxy, ProxyPass and ProxyPassReverse, all requests in your Apache logs are logged with the IP address of the proxying server. The IP address of the original client doing the request is not logged, making it difficult to trace problems and run statistics.

Short answer

There is no easy way to fix this. Use the log of the proxying server instead, which logs the original client IPs you're looking for.

Long answer

You can fix this for your ac...

I am talking about development speed. When your application starts growing and you start adding gems, it starts to take really long to start up, be it the server, console or just running a single spec.

Zeus is smart, you don’t have to put it in your Gemfile or run it with Bundler, all you need to do is create a JSON config file via zeus init and then start the server zeus start.

After that, you’re ready to go, all you need to do is prefix every command with zeus. That means rails server becomes zeus server, `rails console...

Our old solution for cronjobs, the "craken" plugin, is no longer maintained and does not work on Rails 3.2+.

We will instead use the whenever gem.

"Whenever" works just like "craken", by putting your rake tasks into the server's cron table. Everything seems to work just like we need it.

Installation for new projects

1. Add "whenever" to your Gemfile:

    group :deploy do
      gem 'whenever', require: false
    end
   

2. Add it to your config/deploy.rb:
   ...

Connect to your IMAP server. If you have SSL enabled:

openssl s_client -connect your-server:993

if your server supports STARTTLS:

openssl s_client -starttls imap -connect your-server:143

otherwise use netcat or telnet (you shouldn't do cleartext stuff nowadays...).
You should see something like this:

...
. OK Pre-login capabilities listed, post-login capabilities have more.

To log into IMAP, send the following string (incl. "01"!):

01 LOGIN user@domani.io $password

The server should return something like:

* C...

Using Ruby 1.8.7 you will not be able to use the maximum versions Rubygems 1.8.30 and Bundler 1.17.3 with https://rubygems.org/ anymore. This is a result of a server certificate on December 5th, 2020. The resulting errors will look like following:

• TypeError: can't modify frozen object
• Could not verify the SSL certificate for https://rubygems.org/*
• Bundler::Fetcher::CertificateFailureError: Could not verify the SSL certificate for https://index.rubygems.org/versions.
• `Error fetching data: hostname was not m...

SimpleForm is a great approach to simplifying your forms, and it comes with lots of well-defined input types. However, the :grouped_select type seems to be overly complicated for most use cases.

Example

Consider this example, from the documentation:

form.input :country_id, collection: @continents,
  as: :grouped_select, group_method: :countries

While that looks easy enough at a first glance, look closer. The example passes @continents for a country_id.\
SimpleForm actua...

A flat folder structure can be cool if you have only a few folders but can be painful for huge amounts. We recently had this issue in a project with more than 100.000 attachments, where we used a structure like this /attachments/123456789/file.pdf.

Even the ls command lasted several minutes to show us the content of the attachments folder.

So we decided to use a more hierarchical structure with a limited maximum of folder per layer. Here are a few tips how to migrate your files to their new...

If you have a replication error with MySQL and you know the "error" is okay (e.g. you've executed the same statement at the same time on 2 masters which sync each other), you can skip this error and continue with the replication without having to set up the slave from the ground up.

stop slave;
set global sql_slave_skip_counter = 1;
start slave;

But what if you have multiple errors which you want to skip? (e.g. you've executed multiple statement at the same time on 2 masters which sync each other)
Still do not use a value highe...

Travis changed their default distribution from Ubuntu 14.04 (trusty) to 16.04 (precise). This might break your test setup for new builds.

You can solve this issue by freezing your test distribution in the .travis.yml to Ubuntu 14.04 until you have the time to solve all the issues you will have in 16.04:

dist: trusty

Error details

Here are few indicators that you ran into this issue:

Connection to the PostgreSQL database does not work anymore

Your travis-ci builds might have started failing on the usual

psql -c...

When storing files for lots of records in the server's file system, Carrierwave's default store_dir approach may cause issues, because some directories will hold too many entries.

The default storage directory from the Carrierwave templates looks like so:

class ExampleUploader < CarrierWave::Uploader::Base
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
end

If you store files for 500k records, that store_dir's parent directory will have 500k sub-directories which will cause some...

Resque comes with its own dashboard (Resque server) that you can mount inside your Rails 3 application with

#config/routes.rb:

require 'resque/server'

My::Application.routes.draw do
  # ...

  mount Resque::Server => '/resque'
end

Unfortunately, since this bypasses the filters in your ApplicationController, everyone can access this dashboard now (unless you have some Rack-based authentication in place, like Devise).

If you're using ...

Consider you have a website vhost listening to www.example.com, redirecting all incoming requests that do not talk about the configured hostname (this is often used to redirect users to http://www.example.com when entering only http://example.com/).

If you want to make a request to that site's web server without actually talking to www.example.com (e.g. because this is a load balancer's address but you want to access one specific machine), you cannot just request machine1.example.com or localhost as the above vhost will redirect...