graphql-engine/server/src-lib/Hasura/Server/API/V2Query.hs
Antoine Leblanc 6e574f1bbe harmonize network manager handling
## Description

### I want to speak to the `Manager`

Oh boy. This PR is both fairly straightforward and overreaching, so let's break it down.

For most network access, we need a [`HTTP.Manager`](https://hackage.haskell.org/package/http-client-0.1.0.0/docs/Network-HTTP-Client-Manager.html). It is created only once, at the top level, when starting the engine, and is then threaded through the application to wherever we need to make a network call. As of main, the way we do this is not standardized: most of the GraphQL execution code passes it "manually" as a function argument throughout the code. We also have a custom monad constraint, `HasHttpManagerM`, that describes a monad's ability to provide a manager. And, finally, several parts of the code store the manager in some kind of argument structure, such as `RunT`'s `RunCtx`.

This PR's first goal is to harmonize all of this: we always create the manager at the root, and we already have it when we do our very first `runReaderT`. Wouldn't it make sense for the rest of the code to not manually pass it anywhere, to not store it anywhere, but to always rely on the current monad providing it? This is, in short, what this PR does: it implements a constraint on the base monads, so that they provide the manager, and removes most explicit passing from the code.

### First come, first served

One way this PR goes a tiny bit further than "just" doing the aforementioned harmonization is that it starts the process of implementing the "Services oriented architecture" roughly outlined in this [draft document](https://docs.google.com/document/d/1FAigqrST0juU1WcT4HIxJxe1iEBwTuBZodTaeUvsKqQ/edit?usp=sharing). Instead of using the existing `HasHTTPManagerM`, this PR revamps it into the `ProvidesNetwork` service.

The idea is, again, that we should make all "external" dependencies of the engine, all things that the core of the engine doesn't care about, a "service". This allows us to define clear APIs for features, to choose different implementations based on which version of the engine we're running, harmonizes our many scattered monadic constraints... Which is why this service is called "Network": we can refine it, moving forward, to be the constraint that defines how all network communication is to operate, instead of relying on disparate classes constraint or hardcoded decisions. A comment in the code clarifies this intent.

### Side-effects? In my Haskell?

This PR also unavoidably touches some other aspects of the codebase. One such example: it introduces `Hasura.App.AppContext`, named after `HasuraPro.Context.AppContext`: a name for the reader structure at the base level. It also transforms `Handler` from a type alias to a newtype, as `Handler` is where we actually enforce HTTP limits; but without `Handler` being a distinct type, any code path could simply do a `runExceptT $ runReader` and forget to enforce them.

(As a rule of thumb, i am starting to consider any straggling `runReaderT` or `runExceptT` as a code smell: we should not stack / unstack monads haphazardly, and every layer should be an opaque `newtype` with a corresponding run function.)

## Further work

In several places, i have left TODOs when i have encountered things that suggest that we should do further unrelated cleanups. I'll write down the follow-up steps, either in the aforementioned document or on slack. But, in short, at a glance, in approximate order, we could:

- delete `ExecutionCtx` as it is only a subset of `ServerCtx`, and remove one more `runReaderT` call
- delete `ServerConfigCtx` as it is only a subset of `ServerCtx`, and remove it from `RunCtx`
- remove `ServerCtx` from `HandlerCtx`, and make it part of `AppContext`, or even make it the `AppContext` altogether (since, at least for the OSS version, `AppContext` is there again only a subset)
- remove `CacheBuildParams` and `CacheBuild` altogether, as they're just a distinct stack that is a `ReaderT` on top of `IO` that contains, you guessed it, the same thing as `ServerCtx`
- move `RunT` out of `RQL.Types` and rename it, since after the previous cleanups **it only contains `UserInfo`**; it could be bundled with the authentication service, made a small implementation detail in `Hasura.Server.Auth`
-  rename `PGMetadaStorageT` to something a bit more accurate, such as `App`, and enforce its IO base

This would significantly simply our complex stack. From there, or in parallel, we can start moving existing dependencies as Services. For the purpose of supporting read replicas entitlement, we could move `MonadResolveSource` to a `SourceResolver` service, as attempted in #7653, and transform `UserAuthenticationM` into a `Authentication` service.

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7736
GitOrigin-RevId: 68cce710eb9e7d752bda1ba0c49541d24df8209f
2023-02-22 15:55:54 +00:00

225 lines
7.9 KiB
Haskell

{-# LANGUAGE ViewPatterns #-}
-- | The RQL query ('/v2/query')
module Hasura.Server.API.V2Query
( RQLQuery,
queryModifiesSchema,
runQuery,
)
where
import Control.Concurrent.Async.Lifted (mapConcurrently)
import Control.Lens (preview, _Right)
import Control.Monad.Trans.Control (MonadBaseControl)
import Data.Aeson
import Data.Aeson.Types (Parser)
import Data.Environment qualified as Env
import Data.Text qualified as T
import GHC.Generics.Extended (constrName)
import Hasura.Backends.BigQuery.DDL.RunSQL qualified as BigQuery
import Hasura.Backends.DataConnector.Adapter.RunSQL qualified as DataConnector
import Hasura.Backends.DataConnector.Adapter.Types (DataConnectorName, mkDataConnectorName)
import Hasura.Backends.MSSQL.DDL.RunSQL qualified as MSSQL
import Hasura.Backends.MySQL.SQL qualified as MySQL
import Hasura.Backends.Postgres.DDL.RunSQL qualified as Postgres
import Hasura.Base.Error
import Hasura.EncJSON
import Hasura.GraphQL.Execute.Backend
import Hasura.Metadata.Class
import Hasura.Prelude
import Hasura.RQL.DDL.Schema
import Hasura.RQL.DML.Count
import Hasura.RQL.DML.Delete
import Hasura.RQL.DML.Insert
import Hasura.RQL.DML.Select
import Hasura.RQL.DML.Types
( CountQuery,
DeleteQuery,
InsertQuery,
SelectQuery,
UpdateQuery,
)
import Hasura.RQL.DML.Update
import Hasura.RQL.Types.Metadata
import Hasura.RQL.Types.Run
import Hasura.RQL.Types.SchemaCache.Build
import Hasura.RQL.Types.Source
import Hasura.SQL.Backend
import Hasura.Server.Types
import Hasura.Services
import Hasura.Session
import Hasura.Tracing qualified as Tracing
import Language.GraphQL.Draft.Syntax qualified as GQL
data RQLQuery
= RQInsert !InsertQuery
| RQSelect !SelectQuery
| RQUpdate !UpdateQuery
| RQDelete !DeleteQuery
| RQCount !CountQuery
| RQRunSql !Postgres.RunSQL
| RQMssqlRunSql !MSSQL.MSSQLRunSQL
| RQCitusRunSql !Postgres.RunSQL
| RQCockroachRunSql !Postgres.RunSQL
| RQMysqlRunSql !MySQL.RunSQL
| RQBigqueryRunSql !BigQuery.BigQueryRunSQL
| RQDataConnectorRunSql !DataConnectorName !DataConnector.DataConnectorRunSQL
| RQBigqueryDatabaseInspection !BigQuery.BigQueryRunSQL
| RQBulk ![RQLQuery]
| -- | A variant of 'RQBulk' that runs a bulk of read-only queries concurrently.
-- Asserts that queries on this lists are not modifying the schema.
--
-- This is mainly used by the graphql-engine console.
RQConcurrentBulk [RQLQuery]
deriving (Generic)
-- | This instance has been written by hand so that "wildcard" prefixes of _run_sql can be delegated to data connectors.
instance FromJSON RQLQuery where
parseJSON = withObject "RQLQuery" \o -> do
t <- o .: "type"
let args :: forall a. FromJSON a => Parser a
args = o .: "args"
dcNameFromRunSql = T.stripSuffix "_run_sql" >=> GQL.mkName >=> preview _Right . mkDataConnectorName
case t of
"insert" -> RQInsert <$> args
"select" -> RQSelect <$> args
"update" -> RQUpdate <$> args
"delete" -> RQDelete <$> args
"count" -> RQCount <$> args
-- Optionally, we can specify a `pg_` prefix. This primarily makes some
-- string interpolation easier in the cross-backend tests.
"run_sql" -> RQRunSql <$> args
"pg_run_sql" -> RQRunSql <$> args
"mssql_run_sql" -> RQMssqlRunSql <$> args
"citus_run_sql" -> RQCitusRunSql <$> args
"cockroach_run_sql" -> RQCockroachRunSql <$> args
"mysql_run_sql" -> RQMysqlRunSql <$> args
"bigquery_run_sql" -> RQBigqueryRunSql <$> args
(dcNameFromRunSql -> Just t') -> RQDataConnectorRunSql t' <$> args
"bigquery_database_inspection" -> RQBigqueryDatabaseInspection <$> args
"bulk" -> RQBulk <$> args
"concurrent_bulk" -> RQConcurrentBulk <$> args
_ -> fail $ "Unrecognised RQLQuery type: " <> T.unpack t
runQuery ::
( MonadIO m,
MonadBaseControl IO m,
MonadError QErr m,
Tracing.MonadTrace m,
MonadMetadataStorage m,
MonadResolveSource m,
MonadQueryTags m,
ProvidesHasuraServices m
) =>
Env.Environment ->
InstanceId ->
UserInfo ->
RebuildableSchemaCache ->
ServerConfigCtx ->
RQLQuery ->
m (EncJSON, RebuildableSchemaCache)
runQuery env instanceId userInfo schemaCache serverConfigCtx rqlQuery = do
when ((_sccReadOnlyMode serverConfigCtx == ReadOnlyModeEnabled) && queryModifiesUserDB rqlQuery) $
throw400 NotSupported "Cannot run write queries when read-only mode is enabled"
(metadata, currentResourceVersion) <- Tracing.trace "fetchMetadata" $ liftEitherM fetchMetadata
result <-
runQueryM env rqlQuery & \x -> do
((js, meta), rsc, ci) <-
-- We can use defaults here unconditionally, since there is no MD export function in V2Query
x
& runMetadataT metadata (_sccMetadataDefaults serverConfigCtx)
& runCacheRWT schemaCache
& peelRun runCtx
pure (js, rsc, ci, meta)
withReload currentResourceVersion result
where
runCtx = RunCtx userInfo serverConfigCtx
withReload currentResourceVersion (result, updatedCache, invalidations, updatedMetadata) = do
when (queryModifiesSchema rqlQuery) $ do
case _sccMaintenanceMode serverConfigCtx of
MaintenanceModeDisabled -> do
-- set modified metadata in storage
newResourceVersion <-
Tracing.trace "setMetadata" $
liftEitherM $
setMetadata currentResourceVersion updatedMetadata
-- notify schema cache sync
Tracing.trace "notifySchemaCacheSync" $
liftEitherM $
notifySchemaCacheSync newResourceVersion instanceId invalidations
MaintenanceModeEnabled () ->
throw500 "metadata cannot be modified in maintenance mode"
pure (result, updatedCache)
queryModifiesSchema :: RQLQuery -> Bool
queryModifiesSchema = \case
RQInsert _ -> False
RQSelect _ -> False
RQUpdate _ -> False
RQDelete _ -> False
RQCount _ -> False
RQRunSql q -> Postgres.isSchemaCacheBuildRequiredRunSQL q
RQCitusRunSql q -> Postgres.isSchemaCacheBuildRequiredRunSQL q
RQCockroachRunSql q -> Postgres.isSchemaCacheBuildRequiredRunSQL q
RQMssqlRunSql q -> MSSQL.isSchemaCacheBuildRequiredRunSQL q
RQMysqlRunSql _ -> False
RQBigqueryRunSql _ -> False
RQDataConnectorRunSql _ _ -> False
RQBigqueryDatabaseInspection _ -> False
RQBulk l -> any queryModifiesSchema l
RQConcurrentBulk l -> any queryModifiesSchema l
runQueryM ::
( MonadError QErr m,
MonadIO m,
MonadBaseControl IO m,
UserInfoM m,
CacheRWM m,
HasServerConfigCtx m,
Tracing.MonadTrace m,
MetadataM m,
MonadQueryTags m
) =>
Env.Environment ->
RQLQuery ->
m EncJSON
runQueryM env rq = Tracing.trace (T.pack $ constrName rq) $ case rq of
RQInsert q -> runInsert q
RQSelect q -> runSelect q
RQUpdate q -> runUpdate q
RQDelete q -> runDelete q
RQCount q -> runCount q
RQRunSql q -> Postgres.runRunSQL @'Vanilla q
RQMssqlRunSql q -> MSSQL.runSQL q
RQMysqlRunSql q -> MySQL.runSQL q
RQCitusRunSql q -> Postgres.runRunSQL @'Citus q
RQCockroachRunSql q -> Postgres.runRunSQL @'Cockroach q
RQBigqueryRunSql q -> BigQuery.runSQL q
RQDataConnectorRunSql t q -> DataConnector.runSQL t q
RQBigqueryDatabaseInspection q -> BigQuery.runDatabaseInspection q
RQBulk l -> encJFromList <$> indexedMapM (runQueryM env) l
RQConcurrentBulk l -> do
when (queryModifiesSchema rq) $
throw500 "Only read-only queries are allowed in a concurrent_bulk"
encJFromList <$> mapConcurrently (runQueryM env) l
queryModifiesUserDB :: RQLQuery -> Bool
queryModifiesUserDB = \case
RQInsert _ -> True
RQSelect _ -> False
RQUpdate _ -> True
RQDelete _ -> True
RQCount _ -> False
RQRunSql _ -> True
RQCitusRunSql _ -> True
RQCockroachRunSql _ -> True
RQMssqlRunSql _ -> True
RQMysqlRunSql _ -> True
RQBigqueryRunSql _ -> True
RQDataConnectorRunSql _ _ -> True
RQBigqueryDatabaseInspection _ -> False
RQBulk q -> any queryModifiesUserDB q
RQConcurrentBulk _ -> False