* File.open("~/face.jpg") raise error:
  `Errno::ENOENT: No such file or directory @ rb_sysopen - ~/face.jpg`

Remove frozen_string_literal magic comment from templates

Follow up of #30348

Don't expose Active Storage routes

Fix typo: `credentails` -> `credentials` [ci skip]

Follow up of ca18922a

These routes are only used internally in Active Storage, and it seems
that there is no need for the user to directly use them.

Therefore, I think that routes should not be exposed to users.

Update Getting Started with Rails [ci skip]

Most interesting to us, 2.4.2 and 2.3.5 include the fix for
https://bugs.ruby-lang.org/issues/13632

Do not add master key and credentials when `pretend` option is specified

Make master key added to gitignore the same value as when creating appplication

It is only used `primary_key` and `connection` in the internal, so it is
not needed to delegate others to `klass` explicitly.
This doesn't change public behavior because `relation` will delegate
missing method to `klass`.

Because `collection.table_name` doesn't respect table alias.
Use `collection.arel_attribute` instead.

Update Active Job Basics [ci skip]

Because `quoted_table_name` doesn't respect table alias. We should use
`arel_attribute` for that, so I added `column_name_from_arel_node` to
generate column name from an arel node.

* Add Sneakers link to documentation list.

Address random `test_or_with_bind_params` failures

Reported at https://travis-ci.org/rails/rails/jobs/274370258

- `Post.find([1, 2])` generates this query below:
```sql
SELECT "posts".* FROM "posts" WHERE "posts"."id" IN ($1, $2)  [["id", 1], ["id", 2]]
```

- `Post.where(id: 1).or(Post.where(id: 2)).to_a` generates this query below:
```sql
SELECT "posts".* FROM "posts" WHERE ("posts"."id" = $1 OR "posts"."id" = $2)  [["id", 1], ["id", 2]]
```

Most of the time these two queries return the same result but the order of records are not guaranteed
from SQL point of view then added `sort` before comparing them.

So using `arel_attribute(primary_key).asc` in `batch_order` instead.

For gitignore generated by `rails new`, key with a leading slash is specified.
https://github.com/rails/rails/blob/69f976b859cae7f9d050152103da018b7f5dda6d/railties/lib/rails/generators/rails/app/templates/gitignore#L11

Therefore, when executing `credentials:edit`, also need leading slack.
In order to avoid such a difference, fixed to use same method for
`rails new` and `credentials:edit`.

Before:

```sql
SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > 2 ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > 4 ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > 6 ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > 8 ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > 10 ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
```

After:

```sql
SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT ?  [["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > ? ORDER BY "posts"."id" ASC LIMIT ?  [["id", 2], ["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > ? ORDER BY "posts"."id" ASC LIMIT ?  [["id", 4], ["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > ? ORDER BY "posts"."id" ASC LIMIT ?  [["id", 6], ["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > ? ORDER BY "posts"."id" ASC LIMIT ?  [["id", 8], ["LIMIT", 2]]
SELECT  "posts".* FROM "posts" WHERE "posts"."id" > ? ORDER BY "posts"."id" ASC LIMIT ?  [["id", 10], ["LIMIT", 2]]
```

Removes most mentions of secrets.secret_key_base and explains
credentials instead.

Also removes some very stale upgrade notices about Rails 3/4.

Update Getting Started with Rails [ci skip]

Fix Active Storage direct uploads in Firefox

Fix created_at [ci skip]

Direct upload on firefox is not working because it can’t handle click
events on “input[type=submit]”.
After a successful upload we can see on console a xml parse error, it
happens because AWS S3 success body response is empty, so changing the
reponseType suppress this error.

Rename activestorage/test/service/configurations.yml to activestorage/test/service/configurations.example.yml

This file is intended to be modified as needed for testing services locally. Changes to it should rarely, if ever, be committed.

* WIP: Add credentials using a generic EncryptedConfiguration class

This is sketch code so far.

* Flesh out EncryptedConfiguration and test it

* Better name

* Add command and generator for credentials

* Use the Pathnames

* Extract EncryptedFile from EncryptedConfiguration and add serializers

* Test EncryptedFile

* Extract serializer validation

* Stress the point about losing comments

* Allow encrypted configuration to be read without parsing for display

* Use credentials by default and base them on the master key

* Derive secret_key_base in test/dev, source it from credentials in other envs

And document the usage.

* Document the new credentials setup

* Stop generating the secrets.yml file now that we have credentials

* Document what we should have instead

Still need to make it happen, tho.

* [ci skip] Keep wording to `key base`; prefer defaults.

Usually we say we change defaults, not "spec" out a release.

Can't use backticks in our sdoc generated documentation either.

* Abstract away OpenSSL; prefer MessageEncryptor.

* Spare needless new when raising.

* Encrypted file test shouldn't depend on subclass.

* [ci skip] Some woordings.

* Ditch serializer future coding.

* I said flip it. Flip it good.

* [ci skip] Move require_master_key to the real production.rb.

* Add require_master_key to abort the boot process.

In case the master key is required in a certain environment
we should inspect that the key is there and abort if it isn't.

* Print missing key message and exit immediately.

Spares us a lengthy backtrace and prevents further execution.

I've verified the behavior in a test app, but couldn't figure the
test out as loading the app just exits immediately with:

```
/Users/kasperhansen/Documents/code/rails/activesupport/lib/active_support/testing/isolation.rb:23:in `load': marshal data too short (ArgumentError)
	from /Users/kasperhansen/Documents/code/rails/activesupport/lib/active_support/testing/isolation.rb:23:in `run'
	from /Users/kasperhansen/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/minitest-5.10.2/lib/minitest.rb:830:in `run_one_method'
	from /Users/kasperhansen/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/minitest-5.10.2/lib/minitest/parallel.rb:32:in `block (2 levels) in start'
```

It's likely we need to capture and prevent the exit somehow.
Kernel.stub(:exit) didn't work. Leaving it for tomorrow.

* Fix require_master_key config test.

Loading the app would trigger the `exit 1` per require_master_key's
semantics, which then aborted the test.

Fork and wait for the child process to finish, then inspect the
exit status.

Also check we aborted because of a missing master key, so something
else didn't just abort the boot.

Much <3 to @tenderlove for the tip.

* Support reading/writing configs via methods.

* Skip needless deep symbolizing.

* Remove save; test config reader elsewhere.

* Move secret_key_base check to when we're reading it.

Otherwise we'll abort too soon since we don't assign the secret_key_base
to secrets anymore.

* Add missing string literal comments; require unneeded yaml require.

* ya ya ya, rubocop.

* Add master_key/credentials after bundle.

Then we can reuse the existing message on `rails new bc4`.

It'll look like:

```
Using web-console 3.5.1 from https://github.com/rails/web-console.git (at master@ce985eb)
Using rails 5.2.0.alpha from source at `/Users/kasperhansen/Documents/code/rails`
Using sass-rails 5.0.6
Bundle complete! 16 Gemfile dependencies, 72 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
Adding config/master.key to store the master encryption key: 97070158c44b4675b876373a6bc9d5a0

Save this in a password manager your team can access.

If you lose the key, no one, including you, can access anything encrypted with it.

      create  config/master.key
```

And that'll be executed even if `--skip-bundle` was passed.

* Ensure test app has secret_key_base.

* Assign secret_key_base to app or omit.

* Merge noise

* Split options for dynamic delegation into its own method and use deep symbols to make it work

* Update error to point to credentials instead

* Appease Rubocop

* Validate secret_key_base when reading it.

Instead of relying on the validation in key_generator move that into
secret_key_base itself.

* Fix generator and secrets test.

Manually add config.read_encrypted_secrets since it's not there by default
anymore.

Move mentions of config/secrets.yml to config/credentials.yml.enc.

* Remove files I have no idea how they got here.

* [ci skip] swap secrets for credentials.

* [ci skip] And now, changelogs are coming.

PERF: Incorrect memoization in `ActiveRecord::Associations::Preloader…

```
require 'active_record'
require 'benchmark/ips'

ActiveRecord::Base.establish_connection(ENV.fetch('DATABASE_URL'))
ActiveRecord::Migration.verbose = false

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, :email
    t.integer :topic_id
    t.timestamps null: false
  end

  create_table :topics, force: true do |t|
    t.string :title
    t.timestamps null: false
  end
end

attributes = {
  name: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
  email: 'foobar@email.com'
}

class Topic < ActiveRecord::Base
  has_many :users
end

class User < ActiveRecord::Base
  belongs_to :topic
end

100.times do
  User.create!(attributes)
end

users = User.first(50)

100.times do
  Topic.create!(title: 'This is a topic', users: users)
end

Benchmark.ips do |x|
  x.config(time: 10, warmup: 5)

  x.report("preload") do
    User.includes(:topic).all.to_a
  end
end
```

```
Calculating -------------------------------------
             preload    25.000  i/100ms
-------------------------------------------------
             preload    251.772  (± 1.2%) i/s -      2.525k
```

```
Calculating -------------------------------------
             preload    26.000  i/100ms
-------------------------------------------------
             preload    270.392  (± 1.1%) i/s -      2.704k
```