feat: enable in-database configuration for pool settings

src/PostgREST/AppState.hs

@@ -83,7 +83,7 @@ data AuthResult = AuthResult
 
 data AppState = AppState
  -- | Database connection pool
- { statePool :: SQL.Pool
+ { statePool :: IORef SQL.Pool
  -- | Database server version, will be updated by the connectionWorker
  , statePgVersion :: IORef PgVersion
  -- | No schema cache at the start. Will be filled in by the connectionWorker
@@ -125,8 +125,9 @@ init conf = do
 
 initWithPool :: AppSockets -> SQL.Pool -> AppConfig -> IO AppState
 initWithPool (sock, adminSock) pool conf = do
- appState <- AppState pool
- <$> newIORef minimumPgVersion -- assume we're in a supported version when starting, this will be corrected on a later step
+ appState <- AppState
+ <$> newIORef pool
+ <*> newIORef minimumPgVersion -- assume we're in a supported version when starting, this will be corrected on a later step
  <*> newIORef Nothing
  <*> pure (pure ())
  <*> newEmptyMVar
@@ -208,7 +209,8 @@ initPool AppConfig{..} =
 -- | Run an action with a database connection.
 usePool :: AppState -> AppConfig -> SQL.Session a -> IO (Either SQL.UsageError a)
 usePool appState@AppState{..} AppConfig{configLogLevel} x = do
- res <- SQL.use statePool x
+ pool <- getPool appState
+ res <- SQL.use pool x
 
  when (configLogLevel > LogCrit) $ do
  whenLeft res (\case
@@ -223,11 +225,17 @@ usePool appState@AppState{..} AppConfig{configLogLevel} x = do
 -- | Flush the connection pool so that any future use of the pool will
 -- use connections freshly established after this call.
 flushPool :: AppState -> IO ()
-flushPool AppState{..} = SQL.release statePool
+flushPool appState = SQL.release =<< getPool appState
 
 -- | Destroy the pool on shutdown.
 destroyPool :: AppState -> IO ()
-destroyPool AppState{..} = SQL.release statePool
+destroyPool appState = SQL.release =<< getPool appState
+
+getPool :: AppState -> IO SQL.Pool
+getPool = readIORef . statePool
+
+putPool :: AppState -> SQL.Pool -> IO ()
+putPool = atomicWriteIORef . statePool
 
 getPgVersion :: AppState -> IO PgVersion
 getPgVersion = readIORef . statePgVersion
@@ -478,6 +486,7 @@ reReadConfig startingUp appState = do
  logWithZTime appState $ "Failed reloading config: " <> err
  Right newConf -> do
  putConfig appState newConf
+ putPool appState =<< initPool newConf
  if startingUp then
  pass
  else

src/PostgREST/Config/Database.hs

@@ -50,6 +50,10 @@ dbSettingsNames =
  ,"db_pre_config"
  ,"db_extra_search_path"
  ,"db_max_rows"
+ ,"db_pool"
+ ,"db_pool_acquisition_timeout"
+ ,"db_pool_max_idletime"
+ ,"db_pool_max_lifetime"
  ,"db_plan_enabled"
  ,"db_pre_request"
  ,"db_prepared_statements"

test/io/configs/expected/no-defaults-with-db-other-authenticator.config

@@ -5,10 +5,10 @@ db-channel-enabled = false
 db-extra-search-path = "public,extensions,other"
 db-max-rows = 100
 db-plan-enabled = true
-db-pool = 1
-db-pool-acquisition-timeout = 30
-db-pool-max-lifetime = 3600
-db-pool-max-idletime = 60
+db-pool = 3
+db-pool-acquisition-timeout = 20
+db-pool-max-lifetime = 360
+db-pool-max-idletime = 20
 db-pool-automatic-recovery = false
 db-pre-request = "test.other_custom_headers"
 db-prepared-statements = false

test/io/configs/expected/no-defaults-with-db.config

@@ -5,10 +5,10 @@ db-channel-enabled = false
 db-extra-search-path = "public,extensions,private"
 db-max-rows = 1000
 db-plan-enabled = true
-db-pool = 1
-db-pool-acquisition-timeout = 30
-db-pool-max-lifetime = 3600
-db-pool-max-idletime = 60
+db-pool = 2
+db-pool-acquisition-timeout = 15
+db-pool-max-lifetime = 180
+db-pool-max-idletime = 10
 db-pool-automatic-recovery = false
 db-pre-request = "test.custom_headers"
 db-prepared-statements = false

test/io/db_config.sql

@@ -18,6 +18,10 @@ ALTER ROLE db_config_authenticator SET pgrst.db_prepared_statements = 'false';
 ALTER ROLE db_config_authenticator SET pgrst.db_pre_request = 'test.custom_headers';
 ALTER ROLE db_config_authenticator SET pgrst.db_max_rows = '1000';
 ALTER ROLE db_config_authenticator SET pgrst.db_extra_search_path = 'public, extensions';
+ALTER ROLE db_config_authenticator SET pgrst.db_pool = '2';
+ALTER ROLE db_config_authenticator SET pgrst.db_pool_acquisition_timeout = '15';
+ALTER ROLE db_config_authenticator SET pgrst.db_pool_max_lifetime = '180';
+ALTER ROLE db_config_authenticator SET pgrst.db_pool_max_idletime = '10';
 ALTER ROLE db_config_authenticator SET pgrst.not_existing = 'should be ignored';
 ALTER ROLE db_config_authenticator SET pgrst.server_cors_allowed_origins = 'http://example.com';
 ALTER ROLE db_config_authenticator SET pgrst.server_trace_header = 'CF-Ray';
@@ -42,11 +46,7 @@ ALTER ROLE db_config_authenticator SET pgrst.log_level = 'ignored';
 ALTER ROLE db_config_authenticator SET pgrst.db_uri = 'postgresql://ignored';
 ALTER ROLE db_config_authenticator SET pgrst.db_channel_enabled = 'ignored';
 ALTER ROLE db_config_authenticator SET pgrst.db_channel = 'ignored';
-ALTER ROLE db_config_authenticator SET pgrst.db_pool = 'ignored';
 ALTER ROLE db_config_authenticator SET pgrst.db_pool_timeout = 'ignored';
-ALTER ROLE db_config_authenticator SET pgrst.db_pool_acquisition_timeout = 'ignored';
-ALTER ROLE db_config_authenticator SET pgrst.db_pool_max_lifetime = 'ignored';
-ALTER ROLE db_config_authenticator SET pgrst.db_pool_max_idletime = 'ignored';
 ALTER ROLE db_config_authenticator SET pgrst.db_config = 'true';
 
 -- other authenticator reloadable config options
@@ -64,6 +64,10 @@ ALTER ROLE other_authenticator SET pgrst.db_prepared_statements = 'false';
 ALTER ROLE other_authenticator SET pgrst.db_pre_request = 'test.other_custom_headers';
 ALTER ROLE other_authenticator SET pgrst.db_max_rows = '100';
 ALTER ROLE other_authenticator SET pgrst.db_extra_search_path = 'public, extensions, other';
+ALTER ROLE other_authenticator SET pgrst.db_pool = '3';
+ALTER ROLE other_authenticator SET pgrst.db_pool_acquisition_timeout = '20';
+ALTER ROLE other_authenticator SET pgrst.db_pool_max_lifetime = '360';
+ALTER ROLE other_authenticator SET pgrst.db_pool_max_idletime = '20';
 ALTER ROLE other_authenticator SET pgrst.openapi_mode = 'disabled';
 ALTER ROLE other_authenticator SET pgrst.openapi_security_active = 'false';
 ALTER ROLE other_authenticator SET pgrst.server_cors_allowed_origins = 'http://example.com';

test/io/fixtures.sql

@@ -198,3 +198,11 @@ $$ language sql set statement_timeout = '4s';
 create function get_postgres_version() returns int as $$
  select current_setting('server_version_num')::int;
 $$ language sql;
+
+create function change_db_pool_config(size int) returns void as $_$
+begin
+ execute format($$
+ alter role postgrest_test_authenticator set pgrst.db_pool = %L;
+ $$, size);
+ perform pg_notify('pgrst', 'reload config');
+end $_$ volatile security definer language plpgsql;

test/io/test_io.py

@@ -582,6 +582,42 @@ def test_pool_acquisition_timeout(level, defaultenv, metapostgrest):
  assert "Timed out acquiring connection from connection pool." in output[1]
 
 
+def test_db_pool_configuration_reload(defaultenv):
+ "Verify that PGRST_DB_POOL setting is reloaded correctly"
+
+ env = {
+ **defaultenv,
+ "PGRST_DB_POOL": "1",
+ "PGRST_DB_POOL_ACQUISITION_TIMEOUT": "1", # 1 second
+ }
+
+ with run(env=env) as postgrest:
+ response = postgrest.session.post(
+ "/rpc/change_db_pool_config", data={"size": 2}
+ )
+ assert response.status_code == 204
+
+ sleep_until_postgrest_config_reload()
+
+ def sleep():
+ res = postgrest.session.get("/rpc/sleep?seconds=1")
+ assert res.status_code == 204
+
+ def get_projects():
+ res = postgrest.session.get("/projects")
+ assert res.status_code == 200
+
+ thread_1 = Thread(target=sleep)
+ thread_1.start()
+
+ # This would return an error if the DB_POOL is only 1
+ thread_2 = Thread(target=get_projects)
+ thread_2.start()
+
+ thread_1.join()
+ thread_2.join()
+
+
 def test_change_statement_timeout_held_connection(defaultenv, metapostgrest):
  "Statement timeout changes take effect immediately, even with a request outliving the reconfiguration"