Setup your own gitlab runner

To add your own gitlab runner, follow the steps below

  • Create your runner, in EC2, Google, or any other cloud provider and have ssh access to it.
  • Login to your runner from the previous step and install the gitlab-runner (there are various methods described here: https://docs.gitlab.com/runner/install/. We install using Gitlab’s repositories)
  • Register the gitlab-runner by following the instructions here: https://docs.gitlab.com/runner/register/index.html . You would need to get the token for each project you want to register your runner with (Gitlab -> Settings -> CI/CD -> Runners -> Expand). You can use different executors for your running during the registration such as docker, shell etc.
  • Go to your Gitlab project and find the runner you register above and enable it for the project. You should also add the tags: name_of_your_runner in your .gitlab-ci.yml file.

Cannot login to MariaDB server with root account

Problem

You are trying to login to MariaDB with the root user, but even after resetting the password, it is still not possible to login.

Solution

It seems that certain MariaDB packages that come with Linux distributions use the unix_socket as the authentication method.

MariaDB [mysql]> SELECT user, host, plugin FROM user WHERE user='root';
+------+-----------+-------------+
| user | host      | plugin      |
+------+-----------+-------------+
| root | localhost | unix_socket |
+------+-----------+-------------+
1 row in set (0.00 sec)

Change the plugin as described here (https://stackoverflow.com/a/43424234) with the following:

MariaDB [mysql]> UPDATE mysql.user SET plugin = '' WHERE user = 'root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Error installing json 1.8.3 with ruby 2.4

Problem

You are trying to install the gems for your rails application in a new computer, or by using ruby 2.4 and you get the following error:

An error occurred while installing json (1.8.3), and Bundler cannot continue.
Make sure that `gem install json -v '1.8.3'` succeeds before bundling.

Solution

Remove your old Gemfile.lock file and run bundle again. A newer version of json (ie 1.8.6) should be installed.

Routing rspec with nested routes

Problem

You would like to add a routing rspec test in your rails application that tests for a nested route.
So while you have something like the following in your config/routes.rb file:

namespace :admin do
  resources :users do
    resources :audits, only: [:index]
  end
end

you want to add the following test for your route:

expect(get: '/admin/users/:user_id/audits').to route_to(controller: 'admin/audits', action: 'index')

but you are getting an error like the following:

The recognized options <{"controller"=>"admin/audits", "action"=>"index", "user_id"=>":user_id"}> did not match <{"controller"=>"admin/audits", "action"=>"index"}>, difference:.
       --- expected
       +++ actual
       @@ -1 +1 @@
       -{"controller"=>"admin/audits", "action"=>"index"}
       +{"controller"=>"admin/audits", "action"=>"index", "user_id"=>":user_id"}

Solution

You will need to change your rspec to the following using any number for the user_id:

expect(get: '/admin/users/42/audits').to route_to(controller: 'admin/audits', action: 'index', user_id: '42')

Solution adapted from here

ActiveRecord::InvalidForeignKey: PG::ForeignKeyViolation: ERROR: …

Problem

You have a Ruby on Rails application/engine with some tests in Minitest and using postgresql as the db. In the original development environment all the tests that use fixtures and foreign key validations pass, but when you try to move to a different environment with new database some or all of you tests fail with a message that refers to the ForeignKeyViolation as in:

ActiveRecord::InvalidForeignKey: PG::ForeignKeyViolation: ERROR:  insert or update on table "tbl_name" violates foreign key constraint "tbl_name_cln_name_fk_tbl_name_fk"
DETAIL:  Key (col_name)=(VALUE) is not present in table "fk_tbl_name".

Solution

Since active record disables the foreign keys before loading the fixtures in the database, the user that you run the tests with needs to have superuser permissions in the test database. Otherwise the fixtures are not loaded. So add the superuser permissions to your user:

psql -U super_user
alter role use_for_tests superuser;

You may need to drop and create your test database.

Running a specific Cop in Rubocop

Problem

You are working on an existing rails project with many rubocop warnings and you would like to fix certain types or warnings by getting only the specified files.

Solution

So for example when you use rubocop you first get the following for all the files in the project:

rubocop
799 files inspected, 17214 offenses detected

You can get a grouping of the errors by using the following:

rubocop --format offenses
7176 Style/StringLiterals
3596 Metrics/LineLength
1031 Style/VariableName
790  Style/IndentationConsistency
548  Style/SpaceAroundOperators
423  Style/Documentation
415  Style/HashSyntax
386  Style/TrailingWhiteSpace
198  Style/SpaceAfterComma
...

If you would like to know only the files for a certain type of warning to be able to fix them you could try the following:

rubocop --only Style/TrailingWhitespace
..... list of files
799 files inspected, 386 offenses detected

Using Array.wrap in Rails when the results could either be a string or an array

Problem

You want to use some array method in a value returned, which can either be a single value or an array of values.

Solution

Rails ActiveSupport Array, provides a method called wrap, that can be used to:

Wraps its argument in an array unless it is already an array (or array-like)

Full explanation of the method here.

Thanks Miles