feat: add pre-config function

Allows using the in-database configuration without SUPERUSER

CHANGELOG.md

@@ -11,6 +11,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
    + New option `db-pool-max-idletime` (default 30s).
    + This is equivalent to the old option `db-pool-timeout` of PostgREST 10.0.0.
    + A config alias for `db-pool-timeout` is included.
+ - #2703, Add pre-config function - @steve-chavez
+    + New config option `db-pre-config`(empty by default)
+    + Allows using the in-database configuration without SUPERUSER
 
 ## [11.0.1] - 2023-04-27
 

src/PostgREST/CLI.hs

@@ -136,6 +136,9 @@ exampleConfigFile =
       |## Enable in-database configuration
       |db-config = true
       |
+      |## Function for in-database configuration
+      |## db-pre-config = "postgrest.pre_config"
+      |
       |## Extra schemas to add to the search_path of every request
       |db-extra-search-path = "public"
       |

src/PostgREST/Config.hs

@@ -80,6 +80,7 @@ data AppConfig = AppConfig
   , configDbRootSpec               :: Maybe QualifiedIdentifier
   , configDbSchemas                :: NonEmpty Text
   , configDbConfig                 :: Bool
+  , configDbPreConfig              :: Maybe QualifiedIdentifier
   , configDbTxAllowOverride        :: Bool
   , configDbTxRollbackAll          :: Bool
   , configDbUri                    :: Text
@@ -144,6 +145,7 @@ toText conf =
       ,("db-root-spec",              q . maybe mempty dumpQi . configDbRootSpec)
       ,("db-schemas",                q . T.intercalate "," . toList . configDbSchemas)
       ,("db-config",                     T.toLower . show . configDbConfig)
+      ,("db-pre-config",             q . maybe mempty dumpQi . configDbPreConfig)
       ,("db-tx-end",                 q . showTxEnd)
       ,("db-uri",                    q . configDbUri)
       ,("db-use-legacy-gucs",            T.toLower . show . configDbUseLegacyGucs)
@@ -240,6 +242,7 @@ parser optPath env dbSettings roleSettings =
     <*> (fromList . maybe ["public"] splitOnCommas <$> optWithAlias (optValue "db-schemas")
                                                                     (optValue "db-schema"))
     <*> (fromMaybe True <$> optBool "db-config")
+    <*> (fmap toQi <$> optString "db-pre-config")
     <*> parseTxEnd "db-tx-end" snd
     <*> parseTxEnd "db-tx-end" fst
     <*> (fromMaybe "postgresql://" <$> optString "db-uri")

src/PostgREST/Config/Database.hs

@@ -35,6 +35,7 @@ dbSettingsNames :: [Text]
 dbSettingsNames =
   (prefix <>) <$>
   ["db_anon_role"
+  ,"db_pre_config"
   ,"db_extra_search_path"
   ,"db_max_rows"
   ,"db_plan_enabled"
@@ -64,21 +65,21 @@ pgVersionStatement = SQL.Statement sql HE.noParams versionRow
     sql = "SELECT current_setting('server_version_num')::integer, current_setting('server_version')"
     versionRow = HD.singleRow $ PgVersion <$> column HD.int4 <*> column HD.text
 
-queryDbSettings :: Bool -> Session [(Text, Text)]
-queryDbSettings prepared =
-  let transaction = if prepared then SQL.transaction else SQL.unpreparedTransaction in
-  transaction SQL.ReadCommitted SQL.Read $ SQL.statement dbSettingsNames $ dbSettingsStatement prepared
-
--- | Get db settings from the connection role. Global settings will be overridden by database specific settings.
--- i.e. Doing:
---  ALTER ROLE authenticator IN DATABASE postgres SET <prefix>jwt_aud = 'val';
---  ALTER ROLE authenticator SET <prefix>jwt_aud = 'overridden';
--- Will result in <prefix>jwt_aud = 'overridden'
+-- | Query the in-database configuration. The settings have the following priorities:
 --
--- A setting on the database only will have no effect
---  ALTER DATABASE postgres SET <prefix>jwt_aud = 'xx'
-dbSettingsStatement :: Bool -> SQL.Statement [Text] [(Text, Text)]
-dbSettingsStatement = SQL.Statement sql (arrayParam HE.text) decodeSettings
+-- 1. Role + with database-specific settings:
+--    ALTER ROLE authenticator IN DATABASE postgres SET <prefix>jwt_aud = 'val';
+-- 2. Role + with settings:
+--    ALTER ROLE authenticator SET <prefix>jwt_aud = 'overridden';
+-- 3. pre-config function:
+--    CREATE FUNCTION pre_config() .. PERFORM set_config(<prefix>jwt_aud, 'pre_config_aud'..)
+--
+-- The example above will result in <prefix>jwt_aud = 'val'
+-- A setting on the database only will have no effect: ALTER DATABASE postgres SET <prefix>jwt_aud = 'xx'
+queryDbSettings :: Maybe Text -> Bool -> Session [(Text, Text)]
+queryDbSettings preConfFunc prepared =
+  let transaction = if prepared then SQL.transaction else SQL.unpreparedTransaction in
+  transaction SQL.ReadCommitted SQL.Read $ SQL.statement dbSettingsNames $ SQL.Statement sql (arrayParam HE.text) decodeSettings prepared
   where
     sql = [qc|
       WITH
@@ -94,14 +95,26 @@ dbSettingsStatement = SQL.Statement sql (arrayParam HE.text) decodeSettings
                substr(setting, 1, strpos(setting, '=') - 1) as k,
                substr(setting, strpos(setting, '=') + 1) as v
         FROM role_setting
+        {preConfigF}
       )
       SELECT DISTINCT ON (key)
              replace(k, '{prefix}', '') AS key,
              v AS value
       FROM kv_settings
-      WHERE k = ANY($1)
-      ORDER BY key, database DESC;
+      WHERE k = ANY($1) AND v IS NOT NULL
+      ORDER BY key, database DESC NULLS LAST;
     |]
+    preConfigF = case preConfFunc of
+      Nothing   -> mempty
+      Just func -> [qc|
+          UNION
+          SELECT
+            null as database,
+            x as k,
+            current_setting(x, true) as v
+          FROM unnest($1) x
+          JOIN {func}() _ ON TRUE
+      |]::Text
     decodeSettings = HD.rowList $ (,) <$> column HD.text <*> column HD.text
 
 queryRoleSettings :: Bool -> Session RoleSettings

src/PostgREST/Workers.hs

@@ -25,13 +25,17 @@ import Hasql.Connection (acquire)
 import Network.Socket
 import Network.Socket.ByteString
 
-import PostgREST.AppState         (AppState)
-import PostgREST.Config           (AppConfig (..), readAppConfig)
-import PostgREST.Config.Database  (queryDbSettings, queryPgVersion,
-                                   queryRoleSettings)
-import PostgREST.Config.PgVersion (PgVersion (..), minimumPgVersion)
-import PostgREST.Error            (checkIsFatal)
-import PostgREST.SchemaCache      (querySchemaCache)
+import PostgREST.AppState                (AppState)
+import PostgREST.Config                  (AppConfig (..),
+                                          readAppConfig)
+import PostgREST.Config.Database         (queryDbSettings,
+                                          queryPgVersion,
+                                          queryRoleSettings)
+import PostgREST.Config.PgVersion        (PgVersion (..),
+                                          minimumPgVersion)
+import PostgREST.Error                   (checkIsFatal)
+import PostgREST.SchemaCache             (querySchemaCache)
+import PostgREST.SchemaCache.Identifiers (dumpQi)
 
 import qualified PostgREST.AppState as AppState
 
@@ -89,8 +93,8 @@ connectionWorker appState = do
           when configDbChannelEnabled $
             AppState.signalListener appState
           AppState.logWithZTime appState "Connection successful"
-          -- this could be fail because the connection drops, but the
-          -- loadSchemaCache will pick the error and retry again
+          -- this could be fail because the connection drops, but the loadSchemaCache will pick the error and retry again
+          -- We cannot retry after it fails immediately, because db-pre-config could have user errors. We just log the error and continue.
           when configDbConfig $ reReadConfig False appState
           scStatus <- loadSchemaCache appState
           case scStatus of
@@ -237,7 +241,7 @@ reReadConfig startingUp appState = do
   AppConfig{..} <- AppState.getConfig appState
   dbSettings <-
     if configDbConfig then do
-      qDbSettings <- AppState.usePool appState $ queryDbSettings configDbPreparedStatements
+      qDbSettings <- AppState.usePool appState $ queryDbSettings (dumpQi <$> configDbPreConfig) configDbPreparedStatements
       case qDbSettings of
         Left e -> do
           AppState.logWithZTime appState

test/io/configs/expected/aliases.config

@@ -13,6 +13,7 @@ db-prepared-statements = true
 db-root-spec = "open_alias"
 db-schemas = "provided_through_alias"
 db-config = true
+db-pre-config = ""
 db-tx-end = "commit"
 db-uri = "postgresql://"
 db-use-legacy-gucs = true

test/io/configs/expected/boolean-numeric.config

@@ -13,6 +13,7 @@ db-prepared-statements = false
 db-root-spec = ""
 db-schemas = "public"
 db-config = true
+db-pre-config = ""
 db-tx-end = "commit"
 db-uri = "postgresql://"
 db-use-legacy-gucs = true

test/io/configs/expected/boolean-string.config

@@ -13,6 +13,7 @@ db-prepared-statements = false
 db-root-spec = ""
 db-schemas = "public"
 db-config = true
+db-pre-config = ""
 db-tx-end = "commit"
 db-uri = "postgresql://"
 db-use-legacy-gucs = true

test/io/configs/expected/defaults.config

@@ -13,6 +13,7 @@ db-prepared-statements = true
 db-root-spec = ""
 db-schemas = "public"
 db-config = false
+db-pre-config = ""
 db-tx-end = "commit"
 db-uri = "postgresql://"
 db-use-legacy-gucs = true

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

@@ -1,4 +1,4 @@
-db-anon-role = "other"
+db-anon-role = "pre_config_role"
 db-channel = "postgrest"
 db-channel-enabled = false
 db-extra-search-path = "public,extensions,other"
@@ -13,11 +13,12 @@ db-prepared-statements = false
 db-root-spec = "other_root"
 db-schemas = "test,other_tenant1,other_tenant2"
 db-config = true
+db-pre-config = "postgrest.pre_config"
 db-tx-end = "rollback-allow-override"
 db-uri = "postgresql://"
 db-use-legacy-gucs = false
 jwt-aud = "https://otherexample.org"
-jwt-role-claim-key = ".\"other\".\"role\""
+jwt-role-claim-key = ".\"other\".\"pre_config_role\""
 jwt-secret = "ODERREALLYREALLYREALLYREALLYVERYSAFE"
 jwt-secret-is-base64 = true
 log-level = "info"

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

@@ -13,6 +13,7 @@ db-prepared-statements = false
 db-root-spec = "root"
 db-schemas = "test,tenant1,tenant2"
 db-config = true
+db-pre-config = "postgrest.preconf"
 db-tx-end = "commit-allow-override"
 db-uri = "postgresql://"
 db-use-legacy-gucs = false

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

@@ -13,6 +13,7 @@ db-prepared-statements = false
 db-root-spec = "openapi_v3"
 db-schemas = "multi,tenant,setup"
 db-config = false
+db-pre-config = "postgrest.pre_config"
 db-tx-end = "rollback-allow-override"
 db-uri = "tmp_db"
 db-use-legacy-gucs = false

test/io/configs/expected/types.config

@@ -13,6 +13,7 @@ db-prepared-statements = true
 db-root-spec = ""
 db-schemas = "public"
 db-config = true
+db-pre-config = ""
 db-tx-end = "commit"
 db-uri = "postgresql://"
 db-use-legacy-gucs = true

test/io/configs/no-defaults-env.yaml

@@ -15,9 +15,9 @@ PGRST_DB_PRE_REQUEST: please_run_fast
 PGRST_DB_ROOT_SPEC: openapi_v3
 PGRST_DB_SCHEMAS: multi,   tenant,setup
 PGRST_DB_CONFIG: false
+PGRST_DB_PRE_CONFIG: "postgrest.pre_config"
 PGRST_DB_TX_END: rollback-allow-override
 PGRST_DB_URI: tmp_db
-PGRST_DB_EMBED_DEFAULT_JOIN: inner
 PGRST_DB_USE_LEGACY_GUCS: false
 PGRST_JWT_AUD: 'https://postgrest.org'
 PGRST_JWT_ROLE_CLAIM_KEY: '.user[0]."real-role"'

test/io/configs/no-defaults.config

@@ -13,6 +13,7 @@ db-prepared-statements = false
 db-root-spec = "openapi_v3"
 db-schemas = "multi,   tenant,setup"
 db-config = false
+db-pre-config = "postgrest.pre_config"
 db-tx-end = "rollback-allow-override"
 db-uri = "tmp_db"
 db-use-legacy-gucs = false

test/io/db_config.sql

@@ -9,6 +9,7 @@ ALTER ROLE db_config_authenticator SET pgrst.jwt_secret_is_base64 = 'false';
 ALTER ROLE db_config_authenticator SET pgrst.jwt_role_claim_key = '."a"."role"';
 ALTER ROLE db_config_authenticator SET pgrst.db_anon_role = 'anonymous';
 ALTER ROLE db_config_authenticator SET pgrst.db_tx_end = 'commit-allow-override';
+ALTER ROLE db_config_authenticator SET pgrst.db_pre_config = 'postgrest.preconf';
 ALTER ROLE db_config_authenticator SET pgrst.db_schemas = 'test, tenant1, tenant2';
 ALTER ROLE db_config_authenticator SET pgrst.db_root_spec = 'root';
 ALTER ROLE db_config_authenticator SET pgrst.db_plan_enabled = 'true';
@@ -43,7 +44,7 @@ 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 = 'ignored';
+ALTER ROLE db_config_authenticator SET pgrst.db_config = 'true';
 
 -- other authenticator reloadable config options
 CREATE ROLE other_authenticator LOGIN NOINHERIT;
@@ -52,9 +53,6 @@ ALTER ROLE other_authenticator SET pgrst.openapi_server_proxy_uri = 'https://oth
 ALTER ROLE other_authenticator SET pgrst.raw_media_types = 'application/vnd.pgrst.other-db-config';
 ALTER ROLE other_authenticator SET pgrst.jwt_secret = 'ODERREALLYREALLYREALLYREALLYVERYSAFE';
 ALTER ROLE other_authenticator SET pgrst.jwt_secret_is_base64 = 'true';
-ALTER ROLE other_authenticator SET pgrst.jwt_role_claim_key = '."other"."role"';
-ALTER ROLE other_authenticator SET pgrst.db_anon_role = 'other';
-ALTER ROLE other_authenticator SET pgrst.db_tx_end = 'rollback-allow-override';
 ALTER ROLE other_authenticator SET pgrst.db_schemas = 'test, other_tenant1, other_tenant2';
 ALTER ROLE other_authenticator SET pgrst.db_root_spec = 'other_root';
 ALTER ROLE other_authenticator SET pgrst.db_plan_enabled = 'true';
@@ -65,6 +63,32 @@ ALTER ROLE other_authenticator SET pgrst.db_extra_search_path = 'public, extensi
 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_trace_header = 'traceparent';
+ALTER ROLE other_authenticator SET pgrst.db_pre_config = 'postgrest.pre_config';
+
+create schema postgrest;
+grant usage on schema postgrest to db_config_authenticator;
+grant usage on schema postgrest to other_authenticator;
+
+-- pre-config hook
+create or replace function postgrest.pre_config()
+returns void as $$
+begin
+  if current_user = 'other_authenticator' then
+    perform
+      set_config('pgrst.jwt_role_claim_key', '."other"."pre_config_role"', true)
+    , set_config('pgrst.db_anon_role', 'pre_config_role', true)
+    , set_config('pgrst.db_schemas', 'will be overriden with the above ALTER ROLE.. db_schemas', true)
+    , set_config('pgrst.db_tx_end', 'rollback-allow-override', true);
+  else
+    null;
+  end if;
+end $$ language plpgsql;
+
+create or replace function postgrest.preconf()
+returns void as $$
+begin
+  null;
+end $$ language plpgsql;
 
 -- authenticator used for tests that manipulate statement timeout
 CREATE ROLE timeout_authenticator LOGIN NOINHERIT;

test/spec/SpecHelper.hs

@@ -90,6 +90,7 @@ baseCfg = let secret = Just $ encodeUtf8 "reallyreallyreallyreallyverysafe" in
   , configDbRootSpec            = Nothing
   , configDbSchemas             = fromList ["test"]
   , configDbConfig              = False
+  , configDbPreConfig           = Nothing
   , configDbUri                 = "postgresql://"
   , configDbUseLegacyGucs       = True
   , configFilePath              = Nothing