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An empty service shell for Hoodoo. Install the Hoodoo gem and issue command "hoodoo service_foo ..." to use this shell.
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Hoodoo service shell

This is an empty Hoodoo service shell. See the Hoodoo gem and Hoodoo Guides for more about Hoodoo. The shell is analogous to the sort of thing obtained from Rails with rails new {app}, but rather more bare-bones.

  • To modify this shell: clone this repo, make changes and commit in the usual way.
  • To create a new service: install the Hoodoo Gem directly or find some software component locally that has it already bundled; then run (perhaps with bundle exec) hoodoo --help. RBEnv users may need to run rbenv rehash after installing the Gem in order for the hoodoo executable to be available. Follow the printed (terse) usage instructions.
  • In either case: use bundle install to install required gems, as usual.

Ruby 2.3.5 or later is required for service development.

To get started you will need to create an implementation class in folder service/implementations, an interface class referring to it in service/interfaces and update service.rb so that it refers to the interface class(es); delete the guard raise statement. Resource descriptions are put in service/resources, usually within a namespace module. ActiveRecord models can be put in service/models. There is a db folder for schema and migrations; see rake --tasks for more. A Rails-like config folder includes config/database.yml and RSpec-based tests live inside spec.

There is no Rails-like magic in filenames used inside the service folder versus class names; any Ruby file will do, though you are encouraged to follow the usual convention of snake case filenames matching the title case class names with one class per file in general, just because it makes source code easier to navigate. Models, however inside service/models use ActiveRecord so must adhere to all ActiveRecord conventions.


These use rspec - run them with:

bundle exec rspec

Coverage for existing shell template code is provided, including one simple integration test present which will run on the empty shell but intentionally fail once you start writing a real service implementation. Read the comments in the test source at spec/service/integration/example_spec.rb for important notes on how testing works, run rspec on the out-of-box empty shell if you want to verify that it's all OK, then delete the test and fill in the service.rb file so it doesn't raise the initial warning exception.

The Hoodoo Testing Guide has a lot more information and many examples.

Session Details

If in a test environment (see "The Service object" section below) or you have no MEMCACHED_HOST environment variable set, the middleware runs its session system in testing mode and simulates a session ID. The test session includes only one permission set - a default fallback that allows all actions (as this is convenient for tests) - and only one scoping entry, which allows access to all secured HTTP headers. See the DEFAULT_TEST_SESSION description in the Hoodoo RDoc documentation for more information.

Otherwise, the middleware requires the X-Session-ID header to be set to call the API. This ID is used to lookup the relevant session in Memcached. You can use this "for real" in development by running a Memcached instance and configuring the session ID locally:

  • In ~/.bashrc or .zshrc add the following export. Don't forget source ~/.bashrc or source ~/.zshrc

    export MEMCACHED_HOST=localhost:11211
  • Start racksh add your key to memcached using the dalli gem e.g.

    require 'hoodoo/services'
    session =
      :memcached_host = ENV[ 'MEMCACHED_HOST' ]
    # ...and modify 'session' as need be, then...
    result = session.save_to_memcached
    # :fail => Memcached failure; :outdated => already out of date based
    # on Caller version; :ok => succeeded.
  • Set the X-Session-ID in your requests to the value of session.session_id.

Starting your service

  • bundle exec guard - will start on any spare HTTP port and reload itself when files change.
  • PORT=<number> bundle exec guard - will start on HTTP port <number> and reload itself when files change.
  • bundle exec rackup - run Rack directly via Thin on port 9292, with no auto-reloading (might be useful if you're having odd bug issues that you suspect could be due to Guard).

The shell includes a Guardfile covering expected code locations with a commented out section that will auto-run tests if activated. Customise this as necessary.


To get a shell similar to the Rails console, issue command:

bundle exec racksh

Unless you're using an IDE with Ruby 2 support for debugging, then note that the once-standard Ruby debugger gem does not work on Ruby 2. We use byebug instead. To debug a source file, require first:

require byebug

...then add a "breakpoint" via Ruby statement:


...somewhere in your code. For more, see

The Service object

A module called Service is defined in environment.rb and in the out-of-box shell contains configuration items that might be useful.

Service.config.root - local filesystem path to service root folder
Service.config.env  - StringInquirer that gives name of development and
                      related methods

The env entry lets you do things like this:

$ racksh
[1] pry(main)> Service.config.env
=> "development"
[2] pry(main)> Service.config.env.production?
=> false
[3] pry(main)> Service.config.env.development?
=> true

This is the place to add other configuration data, e.g. via a config/initializers/foo.rb file, via:

Service.configure do | config | = :bar


If you use RDoc comments within your source code, then this file, any Ruby files inside folder service and any inside folder lib (should you add one) will be run through the RDoc generator using SDoc for output. Generated documentation will be written to the docs folder, creating that if necessary. Open file docs/rdoc/index.html for the top level index. Use the following commands to build or update, or fully rebuild respectively, the documentation set:

bundle exec rake rdoc
bundle exec rake rerdoc

Other Notes

  • Various Rake tasks are available - run bundle exec rake --tasks to get a list.
  • Use RACK_ENV where you would have used RAILS_ENV for a Rails application.
  • ActiveSupport is included by the Gemfile but not automatically required as it slows down service startup due to the number of Ruby files it includes. Things like obj.present?, nil.try(...) and HashWithIndifferentAccess are available, but only if you require 'active_support/all' (not recommended) or just the things you need with e.g. require 'active_support/core_ext/string' (recommended).


Please see the LICENSE file for licence details. This is authoritative. At the time of writing - though this note might get out of date - the service shell is released under the LGPL v3; see:

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