https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-4-4-released/

> This release includes some bug fixes and some security fixes.
>
> - CVE-2017-17742: HTTP response splitting in WEBrick
> - CVE-2018-6914: Unintentional file and directory creation with directory traversal in tempfile and tmpdir
> - CVE-2018-8777: DoS by large request in WEBrick
> - CVE-2018-8778: Buffer under-read in String#unpack
> - CVE-2018-8779: Unintentional socket creation by poisoned NUL byte in UNIXServer and UNIXSocket
> - CVE-2018-8780: Unintentional directory traversal by poisoned NUL byte in Dir
> - Multiple vulnerabilities in RubyGems

Fix #6809

I don't know why, either

Fix 6734

Yarn was manually installed to meet the Yarn version requirement of
webpacker. Today, Alpine Linux 3.7 provides Yarn new enough.

It is no longer necessary since commit
be9bab17.

Fix #6605

Both of yarn and npm are used in Mastodon, but the combined usage requires
a redundant dependency and may lead to data inconsistency.

Considering that yarn has autoclean feature which npm does not have,
this change replaces all npm usage with yarn.

This change requires documentation update. Most notably, the following
command must be executed before assets precompilation if any system
dependency of node-sass has changed:

yarn install --force --pure-lockfile

When volumes are declared, but the corresponding directories don't exist, permissions for those directories will be root:root instead of mastodon:mastodon..
This changes makes sure the permissions of the volume directories are as expected.

* Set Docker permissions during the build process

* Remove docker_entrypoint.sh and use COPY with chown

when starting the container.

* Reduce container size with clean yarn

* Merge trouble

* Update Yarn to version 1.1.0

* remove hard-coding

* Bump ruby version to 2.4.2

https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-4-2-released/

Gemfile.lock is also updated.

TODO
- [ ] Update Dockerfile with Alpine release of ruby-2.4.2

* Revert jwt version

It seems that jwt 2.0.0 fails in some environment.
ref. https://github.com/zaru/webpush/issues/42

* Bump Ruby version on docker image

* Let make and bundler use multiple cores

* Adds -j option to bundle install instead of bundle config

System default libiconv of Alpine Linux only supports some charset (e.g. UTF-8).
Therefore, the preview card of the page which is not UTF-8 will be broken in the Docker environment.

Using GNU libiconv!

* Specs for language detection

* Use CharlockHolmes instead of NKF

* Correct mistakes

* Correct style

* Set hint_enc instead of falling back and strip_tags

* Improve specs

* Add dependencies

- improve docker_entrypoint.sh
- serve static files with puma by default
- sort packages list
- use virtual package for build deps
- show how to assign UID/GID

Compact Language Detector v3 (CLD3) is the successor of CLD2, which was
used in the previous implementation. CLD3 includes improvements since CLD2,
and supports newer compilers. On the other hand, it has additional
requirements and cld3-ruby, the FFI of CLD3 for Ruby, is still new and may
be still inmature.

Though CLD3 is named after CLD2, it is implemented with a neural network
model, different from the old implementation, which is based on a Naïve
Bayesian classifier.

CLD3 supports newer compilers, such as GCC 6. CLD2 is not compatible with
GCC 6 because it assigns negative values to varibales typed unsigned.
(see internal/cld_generated_cjk_uni_prop_80.cc) The support for GCC 6 and
newer compilers are essential today, when some server operating system
such as Ubuntu Server 16.10 has GCC 6 by default.

On the one hand, CLD3 requires C++11 support. Environments with old
compilers such as Ubuntu Server 14.04 needs to update the system or install
a newer compiler.

CLD3 needs protocol buffers as a new dependency. However,it is not
considered problematic because major server operating systems, CentOS and
Ubuntu Server provide them.

The FFI cld3-ruby was written by me (Akihiko Odaki) for use in Mastodon.
It is still new and may be inmature, but confirmed to pass existing tests.

* Replace browserify with webpack

* Add react-intl-translations-manager

* Do not minify in development, add offline-plugin for ServiceWorker background cache updates

* Adjust tests and dependencies

* Fix production deployments

* Fix tests

* More optimizations

* Improve travis cache for npm stuff

* Re-run travis

* Add back support for custom.scss as before

* Remove offline-plugin and babili

* Fix issue with Immutable.List().unshift(...values) not working as expected

* Make travis load schema instead of running all migrations in sequence

* Fix missing React import in WarningContainer. Optimize rendering performance by using ImmutablePureComponent instead of
React.PureComponent. ImmutablePureComponent uses Immutable.is() to compare props. Replace dynamic callback bindings in
<UI />

* Add react definitions to places that use JSX

* Add Procfile.dev for running rails, webpack and streaming API at the same time

* after yarn upgrade

* after manually removing node-gyp as top level dependency

* update Dockerfile: latest nodejs LTS

* also update imagemagick

* Add eslint-plugin-jsx-a11y.

* Fix npm script.

* Adjust npm scripts so test also runs lint.

* Fix existing lint errors.

* Don't break on a11y issues.

* Add role and tabIndex.

* Add vim and Mac files to .gitignore and .dockerignore.

* Handle htmlFor (partially), a that's actually a button.

* Fix missing tabIndex.

* Add cursor:pointer to load-more

* Revert change to load_more.

* Fixes based on review.

* Update yarn.lock.

* Don't try to install fsevents on Linux (hides warning noise).

* Update rspec-rails to version 3.5.2

* Update addressable to version 2.5.1

* Update autoprefixer-rails to version 6.7.7.1

* Update bullet to version 5.5.1

* Update domain_name to version 0.5.20170404

* Update letter_opener_web to version 1.3.1

* Upate redis-rails to version 5.0.2

* Update active_record_query_trace to version 1.5.4

* Update capistrano-rails to version 1.2.3

* Update dotenv-rails to version 2.2.0

* Update pg to version 0.20.0

* Update tilt to version 2.0.7

* Update warden to version 1.2.7

* Update tins to version 1.13.2

* Update terminal-table to version 1.7.3

* Update oj to version 2.18.5

* Update simplecov to version 0.14.1

* Update uglifier to version 3.1.13

* Update hashdiff to version 0.3.2

* Update webmock to version 2.3.2

* Update devise to version 4.2.1

* Use ruby version 2.4.1

* Update sass to version 3.4.23

* Update puma to version 3.8.2

* Update will_paginate to version 3.1.5

* Update font-awesome-rails to version 4.7.0.1

* Update fuubar to version 2.2.0

* Update pry-rails to version 0.3.6

* Update simple-navigation to version 4.0.5

* Update rubocop to version 0.48.1

* Update doorkeeper to version 4.2.5

* Update faker to version 1.7.3

* Update aws-sdk to version 2.9.5

* Update fabrication to version 2.16.1

* Update hamlit-rails to version 0.2.0

* Update http to version 2.2.1

* Update httplog to version 0.99.2

* Update sidekiq to version 4.2.10

* Update rspec-sidekiq to version 3.0.0

* Update pghero to version 1.6.4

* Update rack-cors to version 0.4.1

* Update i18n-tasks to version 0.9.13

* Update ruby-oembed to version 0.12.0

* Update jquery-rails to version 4.3.1

* Update simple_form to version 3.4.0

* Update react-rails to version 1.11.0

* Update aws-sdk to version 2.9.6

* Update sidekiq-unique-jobs to version 5.0.0

* Update uglifier to version 3.2.0

Optimize Dockerfile, reduce build time.