Module: Moose::Inventory::DB

Extended by:
DB
Included in:
DB
Defined in:
lib/moose_inventory/db/db.rb,
lib/moose_inventory/db/models.rb,
lib/moose_inventory/db/exceptions.rb

Overview

Module for DB-related functionality

Defined Under Namespace

Classes: Group, Groupvar, Host, Hostvar, MooseDBException

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Attribute Details

#db ⇒ Object (readonly)

Returns the value of attribute db.



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# File 'lib/moose_inventory/db/db.rb', line 19

def db
  @db
end

#exceptions ⇒ Object (readonly)

Returns the value of attribute exceptions.



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# File 'lib/moose_inventory/db/db.rb', line 21

def exceptions
  @exceptions
end

#models ⇒ Object (readonly)

Returns the value of attribute models.



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# File 'lib/moose_inventory/db/db.rb', line 20

def models
  @models
end

Class Method Details

.connect ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 223

def self.connect
  return unless @db.nil?

  adapter = Moose::Inventory::Config._settings[:config][:db][:adapter]
  adapter.downcase!

  case adapter
  when 'sqlite3'
    init_sqlite3

  when 'mysql'
    init_mysql

  when 'postgresql'
    init_postgresql

  else
    fail @exceptions[:moose],
         "database adapter #{adapter} is not yet supported."
  end
end

.create_tables ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 172

def self.create_tables # rubocop:disable Metrics/AbcSize
  unless @db.table_exists? :hosts
    @db.create_table(:hosts) do
      primary_key :id
      column :name, :text, unique: true
    end
  end

  unless @db.table_exists? :hostvars
    @db.create_table(:hostvars) do
      primary_key :id
      foreign_key :host_id
      column :name, :text
      column :value, :text
    end
  end

  unless @db.table_exists? :groups
    @db.create_table(:groups) do
      primary_key :id
      column :name, :text, unique: true
    end
  end

  unless @db.table_exists? :groups_groups
    @db.create_table(:groups_groups) do
      primary_key :id
      foreign_key :parent_id, :groups
      foreign_key :child_id,  :groups
    end
  end

  unless @db.table_exists? :groupvars
    @db.create_table(:groupvars) do
      primary_key :id
      foreign_key :group_id
      column :name, :text
      column :value, :text
    end
  end

  unless @db.table_exists? :groups_hosts
    @db.create_table(:groups_hosts) do
      primary_key :id
      foreign_key :host_id,  :hosts
      foreign_key :group_id, :groups
    end
  end
end

.init ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 24

def self.init
  init_exceptions

  # If we allow init more than once, then the db connection is remade,
  # which changes Sequel:DATABASES[0], thereby invalidating the sequel
  # models.  This causes unexpected behavour. That is to say, because
  # of the way Sequel initializes models, this method is not idempotent.
  # In our single-shot application, this shouldn't be a problem. However,
  # our unit tests like to call init multiple times, which borks things.
  # So, we allow init only once, gated by whether @db is nil. In effect,
  # this means we pool the DB connection for the life of the application.
  # Again, not a problem for our one-shot app, but it may be an issue in
  # long-running code. Personally, I don't like this pooling regime -
  # perhaps I'm not understanding how it's supposed to be used?
  #
  # QUESTION: can the models be refreshed, to make then again valid? What if
  #       we "load" instead of "require" the models?
  # ANSWER: Nope, still borks even if we use a load.
  #
  # @db = nil            # <- fails for unit tests
  return unless @db.nil? # <- works for unit tests

  Sequel::Model.plugin :json_serializer
  connect
  create_tables

  # Make our models work
  Sequel::DATABASES[0] = @db
  require_relative 'models'
  # load( load_dir = File.join(File.dirname(__FILE__), "models.rb") )

  # For convenience
  @models = {}
  @models[:host]     = Moose::Inventory::DB::Host
  @models[:hostvar]  = Moose::Inventory::DB::Hostvar
  @models[:group]    = Moose::Inventory::DB::Group
  @models[:groupvar] = Moose::Inventory::DB::Groupvar

end

.init_exceptions ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 65

def self.init_exceptions
  @exceptions ||= {}
  @exceptions[:moose] ||= Moose::Inventory::DB::MooseDBException
end

.init_mysql ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 270

def self.init_mysql
  require 'mysql2'

  # Quick check that expected keys are at least present
  config = Moose::Inventory::Config._settings[:config][:db]
  [:host, :database, :user, :password].each do |key|
    if config[key].nil?
      fail @exceptions[:moose],
           "Expected key #{key} missing in mysql configuration"
    end
  end

  @db = Sequel.mysql2(user: config[:user],
                      password: config[:password],
                      host: config[:host],
                      database: config[:database])
end

.init_postgresql ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 289

def self.init_postgresql
  require 'pg'

  # Quick check that expected keys are at least present
  config = Moose::Inventory::Config._settings[:config][:db]
  [:host, :database, :user, :password].each do |key|
    if config[key].nil?
      fail @exceptions[:moose],
           "Expected key #{key} missing in postgresql configuration"
    end
  end

  @db = Sequel.postgres(user: config[:user],
                        password: config[:password],
                        host: config[:host],
                        database: config[:database])
end

.init_sqlite3 ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 246

def self.init_sqlite3 # rubocop:disable Metrics/AbcSize
  require 'sqlite3'
  require 'fileutils'

  # Quick check that expected keys are at least present & sensible
  config = Moose::Inventory::Config._settings[:config][:db]
  [:file].each do |key|
    if config[key].nil?
      fail @exceptions[:moose],
           "Expected key #{key} missing in sqlite3 configuration"
    end
  end
  config[:file].empty? && fail("SQLite3 DB 'file' cannot be empty")

  # Make sure the directory exists
  dbfile = File.expand_path(config[:file])
  dbdir = File.dirname(dbfile)
  FileUtils.mkdir_p(dbdir) unless Dir.exist?(dbdir)

  # Create and/or open the database file
  @db = Sequel.sqlite(dbfile)
end

.purge ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 136

def self.purge # rubocop:disable Metrics/AbcSize
  adapter = Moose::Inventory::Config._settings[:config][:db][:adapter]
  adapter.downcase!

  if adapter == 'sqlite3'
    # HACK: SQLite3 supposedly supports CASCADE, see
    # https://www.sqlite.org/foreignkeys.html#fk_actions
    # However, when we do a drop_table with :cascade=>true
    # on an sqlite3 database, it throws errors regarding
    # foreign keys constraints. Instead, the following is
    # less efficient, but does work.

    Group.all.each do |g|
      g.remove_all_hosts
      g.remove_all_groupvars
      g.remove_all_children
      g.destroy
    end

    Host.all.each do |h|
      h.remove_all_groups
      h.remove_all_hostvars
      h.destroy
    end

    Groupvar.all.each(&:destroy)
    Hostvar.all.each(&:destroy)

  else
    @db.drop_table(:hosts, :hostvars,
                   :groups, :groupvars, :group_hosts,
                   if_exists: true, cascade: true)
  end
end

.reset ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 124

def self.reset
  fail('Database connection has not been established') if @db.nil?
  # @debug << 'reset'
  purge
  create_tables
end

.transaction ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 71

def self.transaction
  fail('Database connection has not been established') if @db.nil?

  tries = 0

  begin
    @db.transaction(savepoint: true) do
      yield
    end

  rescue Sequel::DatabaseError => e
    # We want to rescue Sqlite3::BusyException.  But, sequel catches that
    # and re-raises it as Sequel::DatabaseError, with a message referencing
    # the original exception class

    # We look into e, to see whether it is a BusyException.  If not,
    # we re-raise immediately.
    raise unless e.message.include?('BusyException')

    # Looks like a BusyException, so we retry, after a random delay.
    tries += 1
    case tries
    when 1..10
      if Moose::Inventory::Config._confopts[:trace] == true
        STDERR.puts e.message
      end
      sleep rand
      retry
    else
      warn('The database appears to be locked by another process, and '\
           " did not become free after #{tries} tries. Giving up. ")

      # TODO: Some useful advice to the user, as to what to do about this error.
      raise
    end

  rescue @exceptions[:moose] => e
    warn 'An error occurred during a transaction, any changes have been rolled back.'

    if Moose::Inventory::Config._confopts[:trace] == true
      STDERR.puts $ERROR_INFO.backtrace
      abort("ERROR: #{e}")
    else
      abort("ERROR: #{e.message}")
    end

  rescue Exception => e
    warn 'An error occurred during a transaction, any changes have been rolled back.'
    raise e
  end
end