path: root/scripts/decomposition/generate-loose-foreign-key

#!/usr/bin/env -S ENABLE_SPRING=0 bin/rails runner -e test

# This is helper script to swap foreign key to loose foreign key
# using DB schema

require 'optparse'

$options = {
  milestone: "#{Gitlab.version_info.major}.#{Gitlab.version_info.minor}",
  cross_schema: false,
  dry_run: false,
  branch: true,
  rspec: true
}

OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options] <filters...>"

  opts.on("-c", "--cross-schema", "Show only cross-schema foreign keys") do |v|
    $options[:cross_schema] = v
  end

  opts.on("-n", "--dry-run", "Do not execute any commands (dry run)") do |v|
    $options[:dry_run] = v
  end

  opts.on("-b", "--[no-]branch", "Create or not a new branch") do |v|
    $options[:branch] = v
  end

  opts.on("-r", "--[no-]rspec", "Create or not a rspecs automatically") do |v|
    $options[:rspec] = v
  end

  opts.on("-m", "--milestone MILESTONE", "Specify custom milestone (current: #{$options[:milestone]})") do |v|
    $options[:milestone] = v
  end

  opts.on("-h", "--help", "Prints this help") do
    puts opts
    exit
  end
end.parse!

unless system("git diff --quiet db/structure.sql")
  raise "The db/structure.sql is changed. Reset branch or commit changes."
end

unless system("git diff --quiet")
  raise "There are uncommitted changes. Commit to continue."
end

if Gitlab::Database.database_base_models.many?
  raise 'Cannot run in multiple-databases mode. Use only `main:` in `config/database.yml`.'
end

puts "Re-creating current test database"
ActiveRecord::Tasks::DatabaseTasks.drop_current
ActiveRecord::Tasks::DatabaseTasks.create_current
ActiveRecord::Tasks::DatabaseTasks.load_schema_current
ActiveRecord::Tasks::DatabaseTasks.migrate
ActiveRecord::Migration.check_pending!
ActiveRecord::Base.connection_pool.disconnect!
puts

def exec_cmd(*args, fail: nil)
  # output full command
  if $options[:dry_run]
    puts ">> #{args.shelljoin}"
    return true
  end

  # truncate up-to 60 chars or first line
  command = args.shelljoin
  truncated_command = command.truncate([command.lines.first.length+3, 120].min)

  puts ">> #{truncated_command}"
  return true if system(*args)

  raise fail if fail

  puts "--------------------------------------------------"
  puts "This command failed:"
  puts ">> #{command}"
  puts "--------------------------------------------------"
  false
end

def has_lfk?(definition)
  Gitlab::Database::LooseForeignKeys.definitions.any? do |lfk_definition|
    lfk_definition.from_table == definition.from_table &&
      lfk_definition.to_table == definition.to_table &&
      lfk_definition.column == definition.column
  end
end

def matching_filter?(definition, filters)
  filters.all? do |filter|
    definition.from_table.include?(filter) ||
      definition.to_table.include?(filter) ||
      definition.column.include?(filter)
  end
end

def columns(*args)
  puts("%5s | %7s | %40s | %20s | %30s | %15s " % args)
end

def add_definition_to_yaml(definition)
  content = YAML.load_file(Rails.root.join('config/gitlab_loose_foreign_keys.yml'))
  table_definitions = content[definition.from_table]

  # insert new entry at random place to avoid conflicts
  unless table_definitions
    table_definitions = []
    insert_idx = rand(content.count+1)

    # insert at a given index in ordered hash
    content = content.to_a
    content.insert(insert_idx, [definition.from_table, table_definitions])
    content = content.to_h
  end

  on_delete =
    case definition.on_delete
    when :cascade
      'async_delete'
    when :nullify
      'async_nullify'
    else
      raise "Unsupported on_delete behavior: #{definition.on_delete}"
    end

  yaml_definition = {
    "table" => definition.to_table,
    "column" => definition.column,
    "on_delete" => on_delete
  }

  # match and update by "table", "column"
  if existing = table_definitions.pluck("table", "column").index([definition.to_table, definition.column])
    puts "Updated existing definition from #{table_definitions[existing]} to #{yaml_definition}."
    table_definitions[existing] = yaml_definition
  else
    puts "Add new definition for #{yaml_definition}."
    table_definitions.append(yaml_definition)
  end

  # emulate existing formatting
  File.write(
    Rails.root.join('config/gitlab_loose_foreign_keys.yml'),
    content.to_yaml.gsub(/^([- ] )/, '  \1')
  )

  exec_cmd("git", "add", "config/gitlab_loose_foreign_keys.yml")
end

def generate_migration(definition)
  timestamp = Time.now.utc.strftime("%Y%m%d%H%M%S")

  # db/post_migrate/20220111221516_remove_projects_ci_pending_builds_fk.rb

  migration_name = "db/post_migrate/#{timestamp}_remove_#{definition.to_table}_#{definition.from_table}_#{definition.column}_fk.rb"
  puts "Writing #{migration_name}"

  content = <<-EOF.strip_heredoc
    # frozen_string_literal: true

    class Remove#{definition.to_table.camelcase}#{definition.from_table.camelcase}#{definition.column.camelcase}Fk < Gitlab::Database::Migration[1.0]
      disable_ddl_transaction!

      def up
        return unless foreign_key_exists?(:#{definition.from_table}, :#{definition.to_table}, name: "#{definition.name}")

        with_lock_retries do
          execute('LOCK #{definition.to_table}, #{definition.from_table} IN ACCESS EXCLUSIVE MODE') if transaction_open?

          remove_foreign_key_if_exists(:#{definition.from_table}, :#{definition.to_table}, name: "#{definition.name}")
        end
      end

      def down
        add_concurrent_foreign_key(:#{definition.from_table}, :#{definition.to_table}, name: "#{definition.name}", column: :#{definition.column}, target_column: :#{definition.primary_key}, on_delete: :#{definition.on_delete})
      end
    end
  EOF

  File.write(migration_name, content)

  exec_cmd("git", "add", migration_name, fail: "Failed to add migration file.")
  exec_cmd("bin/rails", "db:migrate", fail: "Failed to run db:migrate.")
  exec_cmd("git", "add", "db/schema_migrations/#{timestamp}", "db/structure.sql", fail: "There are uncommitted changes. We should not have any.")
  exec_cmd("git diff --exit-code --name-only", fail: "There are uncommitted changes. We should not have any.")
end

def class_by_table_name
  @index_by_table_name ||= ActiveRecord::Base
    .descendants
    .reject(&:abstract_class)
    .map(&:base_class)
    .index_by(&:table_name)
end

def spec_from_clazz(clazz, definition)
  %w[spec/models ee/spec/models].each do |specs_path|
    path = File.join(specs_path, clazz.underscore + "_spec.rb")
    return path if File.exist?(path)
  end

  raise "Cannot find specs for #{clazz} (#{definition.from_table})"
end

def add_test_to_specs(definition)
  return unless $options[:rspec]

  clazz = class_by_table_name[definition.from_table]
  raise "Cannot map #{definition.from_table} to clazz" unless clazz

  spec_path = spec_from_clazz(clazz, definition)
  puts "Adding test to #{spec_path}..."

  spec_test = <<-EOF.strip_heredoc.indent(2)
    context 'loose foreign key on #{definition.from_table}.#{definition.column}' do
      it_behaves_like 'cleanup by a loose foreign key' do
        let!(:parent) { create(:#{definition.to_table.singularize}) }
        let!(:model) { create(:#{definition.from_table.singularize}, #{definition.column.delete_suffix("_id").singularize}: parent) }
      end
    end
  EOF

  # append to end of file with empty line before
  lines = File.readlines(spec_path)
  insert_line = lines.count - 1
  lines.insert(insert_line, "\n", *spec_test.lines)
  File.write(spec_path, lines.join(""))

  # find a matching line
  test_lines = (1..lines.count).select do |line|
    lines[line-1].include?("it_behaves_like 'cleanup by a loose foreign key' do")
  end.join(":")

  loop do
    if system("bin/rspec", "#{spec_path}:#{test_lines}")
      puts "Test seems fine?"
      break
    end

    puts "--------------------------------------------------"
    puts "Test failed:"
    puts "Edit:   vim #{spec_path} (lines #{test_lines})"
    puts "Re-run: bin/rspec #{spec_path}:#{test_lines}"
    puts "--------------------------------------------------"
    puts "Running bash. To exit do 'Ctrl-D' to re-run, or do 'Ctrl-C' to break (and ignore failure)."
    puts

    unless exec_cmd("bash")
      break
    end
  end

  exec_cmd("git", "add", spec_path, fail: "There are uncommitted changes. We should not have any.")
end

def update_no_cross_db_foreign_keys_spec(definition)
  from_column = "#{definition.from_table}.#{definition.column}"
  spec_path = "spec/lib/gitlab/database/no_cross_db_foreign_keys_spec.rb"

  puts "Updating #{spec_path}..."
  lines = File.readlines(spec_path)
  updated = lines.reject { |line| line.strip == from_column }

  if lines.count == updated.count
    puts "Nothing changed."
    return
  end

  File.write(spec_path, updated.join(""))
  exec_cmd("git", "add", spec_path, fail: "Failed to add changes from #{spec_path}")
end

def commit_changes(definition)
  branch_name = "remove-#{definition.to_table}_#{definition.from_table}_#{definition.column}-fk"
  commit_title = "Swap FK #{definition.from_table} to #{definition.to_table} for LFK"
  mr_title = "Swap FK #{definition.from_table}.#{definition.column} to #{definition.to_table} for LFK"
  description = <<-EOF.strip_heredoc
    Swaps FK for #{definition.from_table}.#{definition.column} to #{definition.to_table}

    Changelog: changed
  EOF

  commit_message = "#{commit_title}\n\n#{description}"

  existing_branch = %x[git rev-parse --abbrev-ref HEAD].strip

  if $options[:branch]
    unless exec_cmd("git", "checkout", "-b", branch_name)
      raise "Failed to create branch: #{branch_name}"
    end
  end

  unless exec_cmd("git", "commit", "-m", commit_message)
    raise "Failed to commit changes."
  end

  if $options[:branch]
    exec_cmd("git", "push", "origin", "-u", "HEAD",
      "-o", "merge_request.create",
      "-o", "merge_request.target=#{existing_branch}",
      "-o", "merge_request.milestone=#{$options[:milestone]}",
      "-o", "merge_request.title=#{mr_title}"
    )

    puts
    puts "--------------------------------------------------"
    puts "Put this as MR description:"
    puts "--------------------------------------------------"
    puts <<-EOF.strip_heredoc
      ## What does this MR do and why?
  
      Per https://gitlab.com/groups/gitlab-org/-/epics/7249
  
      As part of our CI "decomposition" efforts we need to remove all foreign keys that are cross-database (ie. between the planned \`main\` and \`ci\` databases). We are going to replace them all with ["loose foreign keys"](https://docs.gitlab.com/ee/development/database/loose_foreign_keys.html).

      Related: <DETAIL>

      ## Validations

      - **Best team to review (check off when reviewed):** TBD
      - [ ] No way for user to access once parent is deleted. Please explain: <DETAIL>
      - [ ] Possible to access once parent deleted but low user impact. Please explain: <DETAIL>
      - [ ] Possible Sidekiq workers that may load directly and possibly lead to exceptions. Please explain: <DETAIL>
      - [ ] Possible user impact to be evaluated or mitigated. Please explain: <DETAIL>
      - [ ] Is this FK safe to be removed to avoid LOCKing problems? (Explanation: https://gitlab.com/groups/gitlab-org/-/epics/7249#note_819662046). Please explain: <DETAIL>

      ## MR acceptance checklist
  
      This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability. 
  
      * [ ] I have evaluated the [MR acceptance checklist](https://docs.gitlab.com/ee/development/code_review.html#acceptance-checklist) for this MR.

      /label ~"ci-decomposition::phase4" ~"database::review pending" ~"devops::enablement" ~"group::sharding" ~"section::enablement" ~"sharding::active" ~"type::feature" ~"workflow::in dev" ~backend ~"ci-decomposition" ~database ~"Category:Sharding"
      /milestone %"#{$options[:milestone]}"
      /assign_reviewer @ahegyi
    EOF
    puts "--------------------------------------------------"
  end
end

all_foreign_keys = ActiveRecord::Base.connection.tables.flat_map do |table|
  ActiveRecord::Base.connection.foreign_keys(table)
end

# Show only cross-schema foreign keys
if $options[:cross_schema]
  all_foreign_keys.select! do |definition|
    Gitlab::Database::GitlabSchema.table_schema(definition.from_table) != Gitlab::Database::GitlabSchema.table_schema(definition.to_table)
  end
end

if $options[:cross_schema]
  puts "Showing cross-schema foreign keys (#{all_foreign_keys.count}):"
else
  puts "Showing all foreign keys (#{all_foreign_keys.count}):"
  puts "Did you meant `#{$0} --cross-schema ...`?"
end

columns("ID", "HAS_LFK", "FROM", "TO", "COLUMN", "ON_DELETE")
all_foreign_keys.each_with_index do |definition, idx|
  columns(idx, has_lfk?(definition) ? 'Y' : 'N', definition.from_table, definition.to_table, definition.column, definition.on_delete)
end
puts

puts "To match FK write one or many filters to match against FROM/TO/COLUMN:"
puts "- #{$0} <filter(s)...>"
puts "- #{$0} ci_job_artifacts project_id"
puts "- #{$0} dast_site_profiles_pipelines"
puts

return if ARGV.empty?

puts "Loading all models..."
# Fix bug with loading `app/models/identity/uniqueness_scopes.rb`
require_relative Rails.root.join('app/models/identity.rb')

%w[app/models/**/*.rb ee/app/models/**/*.rb].each do |filter|
  Dir.glob(filter).each do |path|
    require_relative Rails.root.join(path)
  end
end
puts

puts "Generating Loose Foreign Key for given filters: #{ARGV}"

all_foreign_keys.each_with_index do |definition, idx|
  next unless matching_filter?(definition, ARGV)

  puts "Matched: #{idx} (#{definition.from_table}, #{definition.to_table}, #{definition.column})"

  add_definition_to_yaml(definition)
  generate_migration(definition)
  add_test_to_specs(definition)
  update_no_cross_db_foreign_keys_spec(definition)
  commit_changes(definition)
end
puts