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FIX: Couldn't boot Discourse app with a readonly postgres.

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This commit is contained in:
Guo Xiang Tan 2017-10-17 13:38:46 +08:00
parent 8185b8cb06
commit 1b5ee0ae72
2 changed files with 59 additions and 27 deletions
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34
lib/active_record/connection_adapters/postgresql_fallback_adapter.rb
View File

@ -1,6 +1,7 @@
require 'active_record/connection_adapters/abstract_adapter'
require 'active_record/connection_adapters/postgresql_adapter'
require 'discourse'
require 'sidekiq/pausable'
class PostgreSQLFallbackHandler
include Singleton
@ -48,14 +49,15 @@ class PostgreSQLFallbackHandler
begin
logger.warn "#{log_prefix}: Checking master server..."
connection = ActiveRecord::Base.postgresql_connection(config)
is_connection_active = connection.active?
connection.disconnect!
if connection.active?
connection.disconnect!
ActiveRecord::Base.clear_all_connections!
if is_connection_active
logger.warn "#{log_prefix}: Master server is active. Reconnecting..."
ActiveRecord::Base.clear_active_connections!
ActiveRecord::Base.clear_all_connections!
self.master_up(key)
Discourse.disable_readonly_mode(Discourse::PG_READONLY_MODE_KEY)
disable_readonly_mode
Sidekiq.unpause!
end
rescue => e
@ -68,10 +70,15 @@ class PostgreSQLFallbackHandler
# Use for testing
def setup!
@masters_down = {}
disable_readonly_mode
end
private
def disable_readonly_mode
Discourse.disable_readonly_mode(Discourse::PG_READONLY_MODE_KEY)
end
def config
ActiveRecord::Base.connection_config
end
@ -100,19 +107,30 @@ module ActiveRecord
config = config.symbolize_keys
if fallback_handler.master_down?
Discourse.enable_readonly_mode(Discourse::PG_READONLY_MODE_KEY)
fallback_handler.verify_master
connection = postgresql_connection(config.dup.merge(host: config[:replica_host], port: config[:replica_port]))
connection = postgresql_connection(config.dup.merge(
host: config[:replica_host],
port: config[:replica_port]
))
verify_replica(connection)
Discourse.enable_readonly_mode(Discourse::PG_READONLY_MODE_KEY)
else
begin
now = Time.zone.now
connection = postgresql_connection(config)
fallback_handler.master_down = false
rescue PG::ConnectionBad => e
on_boot = fallback_handler.master_down?.nil?
fallback_handler.master_down = true
fallback_handler.verify_master
raise e
if on_boot
return postgresql_fallback_connection(config)
else
raise e
end
end
end

52
spec/components/active_record/connection_adapters/postgresql_fallback_adapter_spec.rb
View File

@ -6,13 +6,34 @@ describe ActiveRecord::ConnectionHandling do
let(:replica_port) { 6432 }
let(:config) do
ActiveRecord::Base.configurations[Rails.env].merge("adapter" => "postgresql_fallback",
"replica_host" => replica_host,
"replica_port" => replica_port).symbolize_keys!
ActiveRecord::Base.configurations[Rails.env].merge(
"adapter" => "postgresql_fallback",
"replica_host" => replica_host,
"replica_port" => replica_port
).symbolize_keys!
end
let(:multisite_db) { "database_2" }
let(:multisite_config) do
{
host: 'localhost1',
port: 5432,
replica_host: replica_host,
replica_port: replica_port
}
end
let(:postgresql_fallback_handler) { PostgreSQLFallbackHandler.instance }
before do
['default', multisite_db].each do |db|
with_multisite_db(db) do
postgresql_fallback_handler.master_down = false
end
end
end
after do
postgresql_fallback_handler.setup!
end
@ -24,17 +45,6 @@ describe ActiveRecord::ConnectionHandling do
end
context 'when master server is down' do
let(:multisite_db) { "database_2" }
let(:multisite_config) do
{
host: 'localhost1',
port: 5432,
replica_host: replica_host,
replica_port: replica_port
}
end
before do
@replica_connection = mock('replica_connection')
end
@ -59,10 +69,12 @@ describe ActiveRecord::ConnectionHandling do
ActiveRecord::Base.expects(:postgresql_connection).with(configuration).raises(PG::ConnectionBad)
ActiveRecord::Base.expects(:verify_replica).with(@replica_connection)
ActiveRecord::Base.expects(:postgresql_connection).with(configuration.merge(host: replica_host, port: replica_port)).returns(@replica_connection)
ActiveRecord::Base.expects(:postgresql_connection).with(configuration.merge(
host: replica_host, port: replica_port)
).returns(@replica_connection)
end
expect(postgresql_fallback_handler.master_down?).to eq(nil)
expect(postgresql_fallback_handler.master_down?).to eq(false)
expect { ActiveRecord::Base.postgresql_fallback_connection(config) }
.to raise_error(PG::ConnectionBad)
@ -74,7 +86,7 @@ describe ActiveRecord::ConnectionHandling do
expect(Sidekiq.paused?).to eq(true)
with_multisite_db(multisite_db) do
expect(postgresql_fallback_handler.master_down?).to eq(nil)
expect(postgresql_fallback_handler.master_down?).to eq(false)
expect { ActiveRecord::Base.postgresql_fallback_connection(multisite_config) }
.to raise_error(PG::ConnectionBad)
@ -96,7 +108,6 @@ describe ActiveRecord::ConnectionHandling do
expect(Sidekiq.paused?).to eq(false)
expect(ActiveRecord::Base.connection_pool.connections.count).to eq(0)
skip("Figuring out why the following keeps failing to obtain a connection on Travis")
expect(ActiveRecord::Base.connection)
.to be_an_instance_of(ActiveRecord::ConnectionAdapters::PostgreSQLAdapter)
end
@ -106,7 +117,10 @@ describe ActiveRecord::ConnectionHandling do
it 'should raise the right error' do
ActiveRecord::Base.expects(:postgresql_connection).with(config).raises(PG::ConnectionBad).once
ActiveRecord::Base.expects(:postgresql_connection).with(config.dup.merge(host: replica_host, port: replica_port)).raises(PG::ConnectionBad).once
ActiveRecord::Base.expects(:postgresql_connection).with(config.dup.merge(
host: replica_host,
port: replica_port
)).raises(PG::ConnectionBad).once
2.times do
expect { ActiveRecord::Base.postgresql_fallback_connection(config) }