debian-mirror-gitlab/spec/lib/gitlab/database/load_balancing_spec.rb
2021-09-30 23:02:18 +05:30

822 lines
25 KiB
Ruby

# frozen_string_literal: true
require 'spec_helper'
RSpec.describe Gitlab::Database::LoadBalancing do
include_context 'clear DB Load Balancing configuration'
before do
stub_env('ENABLE_LOAD_BALANCING_FOR_FOSS', 'true')
end
describe '.proxy' do
context 'when configured' do
before do
allow(ActiveRecord::Base.singleton_class).to receive(:prepend)
subject.configure_proxy
end
it 'returns the connection proxy' do
expect(subject.proxy).to be_an_instance_of(subject::ConnectionProxy)
end
end
context 'when not configured' do
it 'returns nil' do
expect(subject.proxy).to be_nil
end
it 'tracks an error to sentry' do
expect(Gitlab::ErrorTracking).to receive(:track_exception).with(
an_instance_of(subject::ProxyNotConfiguredError)
)
subject.proxy
end
end
end
describe '.configuration' do
it 'returns a Hash' do
lb_config = { 'hosts' => %w(foo) }
original_db_config = Gitlab::Database.config
modified_db_config = original_db_config.merge(load_balancing: lb_config)
expect(Gitlab::Database).to receive(:config).and_return(modified_db_config)
expect(described_class.configuration).to eq(lb_config)
end
end
describe '.max_replication_difference' do
context 'without an explicitly configured value' do
it 'returns the default value' do
allow(described_class)
.to receive(:configuration)
.and_return({})
expect(described_class.max_replication_difference).to eq(8.megabytes)
end
end
context 'with an explicitly configured value' do
it 'returns the configured value' do
allow(described_class)
.to receive(:configuration)
.and_return({ 'max_replication_difference' => 4 })
expect(described_class.max_replication_difference).to eq(4)
end
end
end
describe '.max_replication_lag_time' do
context 'without an explicitly configured value' do
it 'returns the default value' do
allow(described_class)
.to receive(:configuration)
.and_return({})
expect(described_class.max_replication_lag_time).to eq(60)
end
end
context 'with an explicitly configured value' do
it 'returns the configured value' do
allow(described_class)
.to receive(:configuration)
.and_return({ 'max_replication_lag_time' => 4 })
expect(described_class.max_replication_lag_time).to eq(4)
end
end
end
describe '.replica_check_interval' do
context 'without an explicitly configured value' do
it 'returns the default value' do
allow(described_class)
.to receive(:configuration)
.and_return({})
expect(described_class.replica_check_interval).to eq(60)
end
end
context 'with an explicitly configured value' do
it 'returns the configured value' do
allow(described_class)
.to receive(:configuration)
.and_return({ 'replica_check_interval' => 4 })
expect(described_class.replica_check_interval).to eq(4)
end
end
end
describe '.hosts' do
it 'returns a list of hosts' do
allow(described_class)
.to receive(:configuration)
.and_return({ 'hosts' => %w(foo bar baz) })
expect(described_class.hosts).to eq(%w(foo bar baz))
end
end
describe '.pool_size' do
it 'returns a Fixnum' do
expect(described_class.pool_size).to be_a_kind_of(Integer)
end
end
describe '.enable?' do
before do
clear_load_balancing_configuration
allow(described_class).to receive(:hosts).and_return(%w(foo))
end
it 'returns false when no hosts are specified' do
allow(described_class).to receive(:hosts).and_return([])
expect(described_class.enable?).to eq(false)
end
it 'returns true when Sidekiq is being used' do
allow(Gitlab::Runtime).to receive(:sidekiq?).and_return(true)
expect(described_class.enable?).to eq(true)
end
it 'returns false when running inside a Rake task' do
allow(Gitlab::Runtime).to receive(:rake?).and_return(true)
expect(described_class.enable?).to eq(false)
end
it 'returns true when load balancing should be enabled' do
allow(Gitlab::Runtime).to receive(:sidekiq?).and_return(false)
expect(described_class.enable?).to eq(true)
end
it 'returns true when service discovery is enabled' do
allow(described_class).to receive(:hosts).and_return([])
allow(Gitlab::Runtime).to receive(:sidekiq?).and_return(false)
allow(described_class)
.to receive(:service_discovery_enabled?)
.and_return(true)
expect(described_class.enable?).to eq(true)
end
end
describe '.configured?' do
before do
clear_load_balancing_configuration
end
it 'returns true when Sidekiq is being used' do
allow(described_class).to receive(:hosts).and_return(%w(foo))
allow(Gitlab::Runtime).to receive(:sidekiq?).and_return(true)
expect(described_class.configured?).to eq(true)
end
it 'returns true when service discovery is enabled in Sidekiq' do
allow(described_class).to receive(:hosts).and_return([])
allow(Gitlab::Runtime).to receive(:sidekiq?).and_return(true)
allow(described_class)
.to receive(:service_discovery_enabled?)
.and_return(true)
expect(described_class.configured?).to eq(true)
end
it 'returns false when neither service discovery nor hosts are configured' do
allow(described_class).to receive(:hosts).and_return([])
allow(described_class)
.to receive(:service_discovery_enabled?)
.and_return(false)
expect(described_class.configured?).to eq(false)
end
end
describe '.configure_proxy' do
it 'configures the connection proxy' do
allow(ActiveRecord::Base.singleton_class).to receive(:prepend)
described_class.configure_proxy
expect(ActiveRecord::Base.singleton_class).to have_received(:prepend)
.with(Gitlab::Database::LoadBalancing::ActiveRecordProxy)
end
end
describe '.active_record_models' do
it 'returns an Array' do
expect(described_class.active_record_models).to be_an_instance_of(Array)
end
end
describe '.service_discovery_enabled?' do
it 'returns true if service discovery is enabled' do
allow(described_class)
.to receive(:configuration)
.and_return('discover' => { 'record' => 'foo' })
expect(described_class.service_discovery_enabled?).to eq(true)
end
it 'returns false if service discovery is disabled' do
expect(described_class.service_discovery_enabled?).to eq(false)
end
end
describe '.service_discovery_configuration' do
context 'when no configuration is provided' do
it 'returns a default configuration Hash' do
expect(described_class.service_discovery_configuration).to eq(
nameserver: 'localhost',
port: 8600,
record: nil,
record_type: 'A',
interval: 60,
disconnect_timeout: 120,
use_tcp: false
)
end
end
context 'when configuration is provided' do
it 'returns a Hash including the custom configuration' do
allow(described_class)
.to receive(:configuration)
.and_return('discover' => { 'record' => 'foo', 'record_type' => 'SRV' })
expect(described_class.service_discovery_configuration).to eq(
nameserver: 'localhost',
port: 8600,
record: 'foo',
record_type: 'SRV',
interval: 60,
disconnect_timeout: 120,
use_tcp: false
)
end
end
end
describe '.start_service_discovery' do
it 'does not start if service discovery is disabled' do
expect(Gitlab::Database::LoadBalancing::ServiceDiscovery)
.not_to receive(:new)
described_class.start_service_discovery
end
it 'starts service discovery if enabled' do
allow(described_class)
.to receive(:service_discovery_enabled?)
.and_return(true)
instance = double(:instance)
expect(Gitlab::Database::LoadBalancing::ServiceDiscovery)
.to receive(:new)
.with(an_instance_of(Hash))
.and_return(instance)
expect(instance)
.to receive(:start)
described_class.start_service_discovery
end
end
describe '.db_role_for_connection' do
let(:connection) { double(:conneciton) }
context 'when the load balancing is not configured' do
before do
allow(described_class).to receive(:enable?).and_return(false)
end
it 'returns primary' do
expect(described_class.db_role_for_connection(connection)).to be(:primary)
end
end
context 'when the load balancing is configured' do
let(:proxy) { described_class::ConnectionProxy.new(%w(foo)) }
let(:load_balancer) { described_class::LoadBalancer.new(%w(foo)) }
before do
allow(ActiveRecord::Base.singleton_class).to receive(:prepend)
allow(described_class).to receive(:enable?).and_return(true)
allow(described_class).to receive(:proxy).and_return(proxy)
allow(proxy).to receive(:load_balancer).and_return(load_balancer)
subject.configure_proxy(proxy)
end
context 'when the load balancer returns :replica' do
it 'returns :replica' do
allow(load_balancer).to receive(:db_role_for_connection).and_return(:replica)
expect(described_class.db_role_for_connection(connection)).to be(:replica)
expect(load_balancer).to have_received(:db_role_for_connection).with(connection)
end
end
context 'when the load balancer returns :primary' do
it 'returns :primary' do
allow(load_balancer).to receive(:db_role_for_connection).and_return(:primary)
expect(described_class.db_role_for_connection(connection)).to be(:primary)
expect(load_balancer).to have_received(:db_role_for_connection).with(connection)
end
end
context 'when the load balancer returns nil' do
it 'returns nil' do
allow(load_balancer).to receive(:db_role_for_connection).and_return(nil)
expect(described_class.db_role_for_connection(connection)).to be(nil)
expect(load_balancer).to have_received(:db_role_for_connection).with(connection)
end
end
end
end
# For such an important module like LoadBalancing, full mocking is not
# enough. This section implements some integration tests to test a full flow
# of the load balancer.
# - A real model with a table backed behind is defined
# - The load balancing module is set up for this module only, as to prevent
# breaking other tests. The replica configuration is cloned from the test
# configuraiton.
# - In each test, we listen to the SQL queries (via sql.active_record
# instrumentation) while triggering real queries from the defined model.
# - We assert the desinations (replica/primary) of the queries in order.
describe 'LoadBalancing integration tests', :delete do
before(:all) do
ActiveRecord::Schema.define do
create_table :load_balancing_test, force: true do |t|
t.string :name, null: true
end
end
end
after(:all) do
ActiveRecord::Schema.define do
drop_table :load_balancing_test, force: true
end
end
shared_context 'LoadBalancing setup' do
let(:development_db_config) { ActiveRecord::Base.configurations.configs_for(env_name: 'development').first.configuration_hash }
let(:hosts) { [development_db_config[:host]] }
let(:model) do
Class.new(ApplicationRecord) do
self.table_name = "load_balancing_test"
end
end
before do
# Preloading testing class
model.singleton_class.prepend ::Gitlab::Database::LoadBalancing::ActiveRecordProxy
# Setup load balancing
clear_load_balancing_configuration
allow(ActiveRecord::Base.singleton_class).to receive(:prepend)
subject.configure_proxy(::Gitlab::Database::LoadBalancing::ConnectionProxy.new(hosts))
original_db_config = Gitlab::Database.config
modified_db_config = original_db_config.merge(load_balancing: { hosts: hosts })
allow(Gitlab::Database).to receive(:config).and_return(modified_db_config)
::Gitlab::Database::LoadBalancing::Session.clear_session
end
end
where(:queries, :include_transaction, :expected_results) do
[
# Read methods
[-> { model.first }, false, [:replica]],
[-> { model.find_by(id: 123) }, false, [:replica]],
[-> { model.where(name: 'hello').to_a }, false, [:replica]],
# Write methods
[-> { model.create!(name: 'test1') }, false, [:primary]],
[
-> {
instance = model.create!(name: 'test1')
instance.update!(name: 'test2')
},
false, [:primary, :primary]
],
[-> { model.update_all(name: 'test2') }, false, [:primary]],
[
-> {
instance = model.create!(name: 'test1')
instance.destroy!
},
false, [:primary, :primary]
],
[-> { model.delete_all }, false, [:primary]],
# Custom query
[-> { model.connection.exec_query('SELECT 1').to_a }, false, [:primary]],
# Reads after a write
[
-> {
model.first
model.create!(name: 'test1')
model.first
model.find_by(name: 'test1')
},
false, [:replica, :primary, :primary, :primary]
],
# Inside a transaction
[
-> {
model.transaction do
model.find_by(name: 'test1')
model.create!(name: 'test1')
instance = model.find_by(name: 'test1')
instance.update!(name: 'test2')
end
model.find_by(name: 'test1')
},
true, [:primary, :primary, :primary, :primary, :primary, :primary, :primary]
],
# Nested transaction
[
-> {
model.transaction do
model.transaction do
model.create!(name: 'test1')
end
model.update_all(name: 'test2')
end
model.find_by(name: 'test1')
},
true, [:primary, :primary, :primary, :primary, :primary]
],
# Read-only transaction
[
-> {
model.transaction do
model.first
model.where(name: 'test1').to_a
end
},
true, [:primary, :primary, :primary, :primary]
],
# use_primary
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary do
model.first
model.where(name: 'test1').to_a
end
model.first
},
false, [:primary, :primary, :replica]
],
# use_primary!
[
-> {
model.first
::Gitlab::Database::LoadBalancing::Session.current.use_primary!
model.where(name: 'test1').to_a
},
false, [:replica, :primary]
],
# use_replicas_for_read_queries does not affect read queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.where(name: 'test1').to_a
end
},
false, [:replica]
],
# use_replicas_for_read_queries does not affect write queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.create!(name: 'test1')
end
},
false, [:primary]
],
# use_replicas_for_read_queries does not affect ambiguous queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.connection.exec_query("SELECT 1")
end
},
false, [:primary]
],
# use_replicas_for_read_queries ignores use_primary! for read queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary!
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.where(name: 'test1').to_a
end
},
false, [:replica]
],
# use_replicas_for_read_queries adheres use_primary! for write queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary!
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.create!(name: 'test1')
end
},
false, [:primary]
],
# use_replicas_for_read_queries adheres use_primary! for ambiguous queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary!
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.connection.exec_query('SELECT 1')
end
},
false, [:primary]
],
# use_replicas_for_read_queries ignores use_primary blocks
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary do
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.where(name: 'test1').to_a
end
end
},
false, [:replica]
],
# use_replicas_for_read_queries ignores a session already performed write
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.write!
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
model.where(name: 'test1').to_a
end
},
false, [:replica]
],
# fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.first
model.where(name: 'test1').to_a
end
},
false, [:replica, :replica]
],
# fallback_to_replicas_for_ambiguous_queries for read-only transaction
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.transaction do
model.first
model.where(name: 'test1').to_a
end
end
},
false, [:replica, :replica]
],
# A custom read query inside fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query("SELECT 1")
end
},
false, [:replica]
],
# A custom read query inside a transaction fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.transaction do
model.connection.exec_query("SET LOCAL statement_timeout = 5000")
model.count
end
end
},
true, [:replica, :replica, :replica, :replica]
],
# fallback_to_replicas_for_ambiguous_queries after a write
[
-> {
model.create!(name: 'Test1')
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query("SELECT 1")
end
},
false, [:primary, :primary]
],
# fallback_to_replicas_for_ambiguous_queries after use_primary!
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary!
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query("SELECT 1")
end
},
false, [:primary]
],
# fallback_to_replicas_for_ambiguous_queries inside use_primary
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_primary do
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query("SELECT 1")
end
end
},
false, [:primary]
],
# use_primary inside fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
::Gitlab::Database::LoadBalancing::Session.current.use_primary do
model.connection.exec_query("SELECT 1")
end
end
},
false, [:primary]
],
# A write query inside fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query("SELECT 1")
model.delete_all
model.connection.exec_query("SELECT 1")
end
},
false, [:replica, :primary, :primary]
],
# use_replicas_for_read_queries incorporates with fallback_to_replicas_for_ambiguous_queries
[
-> {
::Gitlab::Database::LoadBalancing::Session.current.use_replicas_for_read_queries do
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.connection.exec_query('SELECT 1')
model.where(name: 'test1').to_a
end
end
},
false, [:replica, :replica]
]
]
end
with_them do
include_context 'LoadBalancing setup'
it 'redirects queries to the right roles' do
roles = []
subscriber = ActiveSupport::Notifications.subscribe('sql.active_record') do |event|
payload = event.payload
assert =
if payload[:name] == 'SCHEMA'
false
elsif payload[:name] == 'SQL' # Custom query
true
else
keywords = %w[load_balancing_test]
keywords += %w[begin commit] if include_transaction
keywords.any? { |keyword| payload[:sql].downcase.include?(keyword) }
end
if assert
db_role = ::Gitlab::Database::LoadBalancing.db_role_for_connection(payload[:connection])
roles << db_role
end
end
self.instance_exec(&queries)
expect(roles).to eql(expected_results)
ensure
ActiveSupport::Notifications.unsubscribe(subscriber) if subscriber
end
end
context 'custom connection handling' do
where(:queries, :expected_role) do
[
# Reload cache. The schema loading queries should be handled by
# primary.
[
-> {
model.connection.clear_cache!
model.connection.schema_cache.add('users')
model.connection.pool.release_connection
},
:primary
],
# Call model's connection method
[
-> {
connection = model.connection
connection.select_one('SELECT 1')
connection.pool.release_connection
},
:replica
],
# Retrieve connection via #retrieve_connection
[
-> {
connection = model.retrieve_connection
connection.select_one('SELECT 1')
connection.pool.release_connection
},
:primary
]
]
end
with_them do
include_context 'LoadBalancing setup'
it 'redirects queries to the right roles' do
roles = []
subscriber = ActiveSupport::Notifications.subscribe('sql.active_record') do |event|
role = ::Gitlab::Database::LoadBalancing.db_role_for_connection(event.payload[:connection])
roles << role if role.present?
end
self.instance_exec(&queries)
expect(roles).to all(eql(expected_role))
ensure
ActiveSupport::Notifications.unsubscribe(subscriber) if subscriber
end
end
end
context 'a write inside a transaction inside fallback_to_replicas_for_ambiguous_queries block' do
include_context 'LoadBalancing setup'
it 'raises an exception' do
expect do
::Gitlab::Database::LoadBalancing::Session.current.fallback_to_replicas_for_ambiguous_queries do
model.transaction do
model.first
model.create!(name: 'hello')
end
end
end.to raise_error(Gitlab::Database::LoadBalancing::ConnectionProxy::WriteInsideReadOnlyTransactionError)
end
end
end
end