## Description
This PR removes `MetadataStorageT`, and cleans up all top-level error handling. In short: this PR changes `MonadMetadataStorage` to explicitly return a bunch of `Either QErr a`, instead of relying on the stack providing a `MonadError QErr`. Since we implement that class on the base monad *below any ExceptT*, this removes a lot of very complicated instances that make assumptions about the shape of the stack.
On the back of this, we can remove several layers of ExceptT from the core of the code, including the one in `RunT`, which allows us to remove several instances of `liftEitherM . runExceptT`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7689
GitOrigin-RevId: 97d600154d690f58c0b93fb4cc2d30fd383fd8b8
Hooks up event trigger codecs from #7237. This required fixing a problem where some backend types implemented `defaultTriggerOnReplication` with `error` which caused the server to crash when evaluating those for default values in codecs. The changes here add a type family to `Backend` called `XEventTriggers` that signals backend support for event triggers, and changes the type of `defaultTriggerOnReplication` to from `TriggerOnReplication` to `Maybe (XEventTriggers b, TriggerOnReplication)` so that it can only be implemented with a `Just` value if `XEventTriggers b` is inhabited. This emulates some existing type families in `Backend`. (Thanks to @daniel-chambers for this suggestion!)
I used the implementation of `defaultTriggerOnReplication` as a signal for event triggers support to prune the Metadata API so that event trigger fields will not appear in the OpenAPI spec for backend types that do not support event triggers. The codec version of the API will also not emit or accept those fields for those backend types. I think I could use `Typeable` to test whether `XEventTriggers` is `Void` instead of testing whether `defaultTriggerOnReplication` is `Nothing`. But the codec implementation will crash anyway if `defaultTriggerOnReplication` is `Nothing`.
I checked to make sure that graphql-engine-pro still compiles.
Ticket: https://hasurahq.atlassian.net/browse/GDC-521
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7295
GitOrigin-RevId: 2b2dd44291513266107ca25cf330319bf53a8b66
Codecs for event triggers, including webhook transforms. These are not hooked into the higher-up table metadata codec yet because some backend implementations implement event triggers with `error` which causes an error when codecs are evaluated. I plan to follow up with another PR to resolve that.
Ticket: https://hasurahq.atlassian.net/browse/GDC-585
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7237
GitOrigin-RevId: 8ce40fe6fedcf8b109d6ca50a505333df855a8ce
Generate more Metadata Inconsistencies instead of startup failures. Specifically this means that
- errors retrieving the main query of an executable GraphQL document, and
- errors during fragment inlining
no longer fail irrecoverably.
This also makes more parts of `buildSchemaCacheRule` into pure code, which is always nice.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7234
GitOrigin-RevId: aebf636c2fb1aad1c2df9a37f7d0b67c1ee40c42
`toLazyByteString` is a little deficient in two ways:
- It allocates relatively large chunks (4KB + 32KB +32KB, etc…) which is wasteful for small ByteStrings
- It shrinks each chunk (Copying the data to a new chunk of exactly the right size) if it's not more than half filled. If we're running the builder right before we send it over the wire, this copy is totally extraneous (we simply end up with more work for the next GC)
part of the effort: https://github.com/hasura/graphql-engine-mono/issues/5518
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7187
GitOrigin-RevId: b499cd49c33da6cfee96be629a36b5c812486e39
## Description
There is a bug in the metadata defaults code, see [the original PR](https://github.com/hasura/graphql-engine-mono/pull/6286).
Steps to reproduce this issue:
* Start a new HGE project
* Start HGE with a defaults argument: `HASURA_GRAPHQL_LOG_LEVEL=debug cabal run exe:graphql-engine -- serve --enable-console --console-assets-dir=./console/static/dist --metadata-defaults='{"backend_configs": {"dataconnector": {"mongo": {"display_name": "BONGOBB", "uri": "http://localhost:8123"}}}}'`
* Add a source (doesn't need to be related to the defaults)
* Export metadata
* See that the defaults are present in the exported metadata
## Related Issues
* Github Issue: https://github.com/hasura/graphql-engine/issues/9237
* Jira: https://hasurahq.atlassian.net/browse/GDC-647
* Original PR: https://github.com/hasura/graphql-engine-mono/pull/6286
## Solution
* The test for if defaults should be included for metadata api operations has been extended to check for updates
* Metadata inconsistencies have been hidden for `/capabilities` calls on startup
## TODO
* [x] Fix bug
* [x] Write tests
* [x] OSS Metadata Migration to correct persisted data - `server/src-rsr/migrations/47_to_48.sql`
* [x] Cloud Metadata Migration - `pro/server/res/cloud/migrations/6_to_7.sql`
* [x] Bump Catalog Version - `server/src-rsr/catalog_version.txt`
* [x] Update Catalog Versions - `server/src-rsr/catalog_versions.txt` (This will be done by Infra when creating a release)
* [x] Log connection error as it occurs *(Already being logged. Requires `--enabled-log-types startup,webhook-log,websocket-log,http-log,data-connector-log`)
* [x] Don't mark metadata inconsistencies for this call.
## Questions
* [ ] Does the `pro/server/res/cloud/migrations/6_to_7.sql` cover the cloud scenarios?
* [ ] Should we have `SET search_path` in migrations?
* [x] What should be in `server/src-rsr/catalog_versions.txt`?
## Testing
To test the solution locally run:
> docker compose up -d
and
> cabal run -- exe:api-tests --skip BigQuery --skip SQLServer --skip '/Test.API.Explain/Postgres/'
## Solution
In `runMetadataQuery` in `server/src-lib/Hasura/Server/API/Metadata.hs`:
```diff
- if (exportsMetadata _rqlMetadata)
+ if (exportsMetadata _rqlMetadata || queryModifiesMetadata _rqlMetadata)
```
This ensures that defaults aren't present in operations that serialise metadata.
Note: You might think that `X_add_source` would need the defaults to be present to add a source that references the defaults, but since the resolution occurs in the schema-cache building phase, the defaults can be excluded for the metadata modifications required for `X_add_source`.
In addition to the code-change, a metadata migration has been introduced in order to clean up serialised defaults.
The following scenarios need to be considered for both OSS and Cloud:
* The user has not had defaults serialised
* The user has had the defaults serialised and no other backends configured
* The user has had the defaults serialised and has also configured other backends
We want to remove as much of the metadata as possible without any user-specified data and this should be reflected in migration `server/src-rsr/migrations/47_to_48.sql`.
## Server checklist
### Catalog upgrade
Does this PR change Hasura Catalog version?
- ✅ Yes
### Metadata
Does this PR add a new Metadata feature?
- ✅ No
### GraphQL
- ✅ No new GraphQL schema is generated
### Breaking changes
- ✅ No Breaking changes
## Changelog
__Component__ : server
__Type__: bugfix
__Product__: community-edition
### Short Changelog
Fixes a metadata defaults serialization bug and introduces a metadata migration to correct data that has been persisted due to the bug.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7034
GitOrigin-RevId: ad7d4f748397a1a607f2c0c886bf0fbbc3f873f2
This PR implements the remaining codecs for table permissions. However the codec for boolean expressions delegates to Aeson instances because Autodocodec doesn't currently have the necessary feature to write a codec for boolean expressions that will reliably parse valid data.
Boolean expressions are objects with keys like `_and`, `_or`, `_exists`, or `<field name>`. The parsing rules for each value depend on the key, so we need to be able to select different codecs for each key. We could do that with an `object` codec, but that doesn't account for the arbitrary field name keys that can be provided. OpenAPI supports object types with "additional properties", but I don't know if we can declare a specific type for those properties. There might or might not be a reasonable path to extending Autodocodec to handle this case.
Ticket: [GDC-585](https://hasurahq.atlassian.net/browse/GDC-585)
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6978
GitOrigin-RevId: 0b0dcfd59ebd1d5022ff2ab86dd8d4c6f93bd039
Dependencies seem to get concatenated very often, so let's use a data structure that supports efficient concatenation.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7050
GitOrigin-RevId: 6331963f99f17d1b908a6038318d8c4834cf4dd7
## Description ✍️
This PR adds support to generate query params directly using a kriti template which can be used to flatten a list of parameter arguments as well.
### Changes in the Metadata API
Earlier the `query_params` key inside `request_transform` used to take in an object of key/value pairs where the `key` represents the query parameter name and `value` points to the value of the parameter or a kriti template which could be resolved to the value.
With this PR, we provide the user with more freedom to generate the complete query string using kriti template. The `query_params` can now take in a string as well which will be a kriti template. This new change needs to be incorporated on the console and CLI metadata import/export as well.
- [x] CLI: Compatible, no changes required
- [ ] Console
## Changelog ✍️
__Component__ : server
__Type__: feature
__Product__: community-edition
### Short Changelog
use kriti template to generate query param from list of arguments
### Related Issues ✍
https://hasurahq.atlassian.net/browse/GS-243
### Solution and Design ✍
We use a kriti template to generate the complete query parameter string.
| Query Template | Output |
|---|---|
| `{{ concat ([concat({{ range _, x := [\"apple\", \"banana\"] }} \"tags={{x}}&\" {{ end }}), \"flag=smthng\"]) }}`| `tags=apple&tags=banana&flag=smthng` |
| `{{ concat ([\"tags=\", concat({{ range _, x := $body.input }} \"{{x}},\" {{ end }})]) }}` | `tags=apple%2Cbanana%2C` |
### Steps to test and verify ✍
- start HGE and make the following request to `http://localhost:8080/v1/metadata`:
```json
{
"type": "test_webhook_transform",
"args": {
"webhook_url": "http://localhost:3000",
"body": {
"action": {
"name": "actionName"
},
"input": ["apple", "banana"]
},
"request_transform": {
"version": 2,
"url": "{{$base_url}}",
"query_params": "{{ concat ([concat({{ range _, x := $body.input }} \"tags={{x}}&\" {{ end }}), \"flag=smthng\"]) }}",
"template_engine": "Kriti"
}
}
}
```
- you should receive the following as output:
```json
{
"body": {
"action": {
"name": "actionName"
},
"input": [
"apple",
"banana"
]
},
"headers": [],
"method": "GET",
"webhook_url": "http://localhost:3000?tags=apple&tags=banana&flag=smthng"
}
```
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6961
Co-authored-by: Tirumarai Selvan <8663570+tirumaraiselvan@users.noreply.github.com>
GitOrigin-RevId: 712ba038f03009edc3e8eb0435e723304943399a
## Description ✍️
This PR introduces a new feature to enable/disable event triggers during logical replication of table data for PostgreSQL and MS-SQL data sources. We introduce a new field `trigger_on_replication` in the `*_create_event_trigger` metadata API. By default the event triggers will not fire for logical data replication.
## Changelog ✍️
__Component__ : server
__Type__: feature
__Product__: community-edition
### Short Changelog
Add option to enable/disable event triggers on logically replicated tables
### Related Issues ✍
https://github.com/hasura/graphql-engine/issues/8814https://hasurahq.atlassian.net/browse/GS-252
### Solution and Design
- By default, triggers do **not** fire when the session mode is `replica` in Postgres, so if the `triggerOnReplication` is set to `true` for an event trigger we run the query `ALTER TABLE #{tableTxt} ENABLE ALWAYS TRIGGER #{triggerNameTxt};` so that the trigger fires always irrespective of the `session_replication_role`
- By default, triggers do fire in case of replication in MS-SQL, so if the `triggerOnReplication` is set to `false` for an event trigger we add a clause `NOT FOR REPLICATION` to the the SQL when the trigger is created/altered, which sets the `is_not_for_replication` for the trigger as `true` and it does not fire during logical replication.
### Steps to test and verify ✍
- Run hspec integration tests for HGE
## Server checklist ✍
### Metadata ✍
Does this PR add a new Metadata feature?
- ✅ Yes
- Does `export_metadata`/`replace_metadata` supports the new metadata added?
- ✅
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6953
Co-authored-by: Puru Gupta <32328846+purugupta99@users.noreply.github.com>
Co-authored-by: Sean Park-Ross <94021366+seanparkross@users.noreply.github.com>
GitOrigin-RevId: 92731328a2bbdcad2302c829f26f9acb33c36135
Mostly trying to avoid tricky `Arrows` syntax, and unnecessary use of the `Hasura.Incremental` framework.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6997
GitOrigin-RevId: 9a2f5883e7e29af164e1581049ae003afec2cbe4
I encountered this dead code while doing other things: it's a type class with a single method which is never called. Deleting the type class allows us to simplify `TableCoreCacheRT` and `TableCacheRT`
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7075
GitOrigin-RevId: 121320349c478a93717b0706037553d8406cbfa9
This increases the speed of `create_query_collection` and `add_collection_to_allowlist` by a factor ~~10~~ 65, by caching the in-memory GraphQL schema. This speedup also applies more broadly to Metadata changes relating to:
- allowlists
- query collections
- cron triggers
- REST endpoints
- API limits
- metrics config
- GraphQL introspection options
- TLS allow lists
- OpenTelemetry
When is construction of the in-memory GraphQL schema cached between Metadata operations?
Before this PR, **never**! It's rebuilt fully, for every role, on every Metadata operation.
However, there are many Metadata operations that don't influence the GraphQL schema. So we should be caching its construction.
The `Hasura.Incremental` framework allows us to cache such constructions: whenever we have an arrow `Rule m a b`, where `a` is the input to the arrow and `b` the output, we can use the `Inc.cache` combinator to obtain a new arrow which is only re-executed when the input `a` changes in a material way. To test this, `a` needs an `Eq` instance. (Before hasura/graphql-engine-mono#6877, this was a `Cacheable` type class which has now been removed.)
We can't simply apply `Inc.cache` to the "Steps 3 and 4" in `buildSchemaCacheRule`, because the inputs (components of `BuildOutputs` such as `SourceCache`) don't have an `Eq` instance.
So the changes to `buildSchemaCacheRule` restructure the code so that the input to "Step 1", namely the Metadata, can be used as a caching key instead, so that `Inc.cache` can be applied to the whole sequence of steps.
That works to cache construction of the GraphQL schema, but it means that now only those Metadata operations that _don't_ influence any of the products of steps 1-4 can use a cached build of the GraphQL schema. The most important intermediate product is `BuildOutputs`. So now the exercise becomes to minimize the amount of stuff stored in `BuildOutputs`, so that as many Metadata operations as possible can be handled outside of the codepath that produces a GraphQL schema.
Per hasura/graphql-engine-mono#6609, the `BuildOutputs` structure is too big, and stores things unnecessarily. Refer to the PR description there for reasoning - the same logic applies to this PR, and simply goes a few steps further. In doing so, it can benefit from hasura/graphql-engine-mono#6765, which allows us to verify at compile time that certain Schema Cache building steps _don't_ generate "Metadata dependencies". If a certain Metadata dependency is never generated, we don't need to handle that case in `deleteMetadataObject`. Thus such intermediate products don't need to be passed through `resolveDependencies`, and thus they don't need to be stored in `BuildOutputs`, and thus their rebuild won't trigger a GraphQL schema rebuild.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6613
GitOrigin-RevId: 27d2e69d3461bd4c32f08febef9995c0369fab3a
What is the `Cacheable` type class about?
```haskell
class Eq a => Cacheable a where
unchanged :: Accesses -> a -> a -> Bool
default unchanged :: (Generic a, GCacheable (Rep a)) => Accesses -> a -> a -> Bool
unchanged accesses a b = gunchanged (from a) (from b) accesses
```
Its only method is an alternative to `(==)`. The added value of `unchanged` (and the additional `Accesses` argument) arises _only_ for one type, namely `Dependency`. Indeed, the `Cacheable (Dependency a)` instance is non-trivial, whereas every other `Cacheable` instance is completely boilerplate (and indeed either generated from `Generic`, or simply `unchanged _ = (==)`). The `Cacheable (Dependency a)` instance is the only one where the `Accesses` argument is not just passed onwards.
The only callsite of the `unchanged` method is in the `ArrowCache (Rule m)` method. That is to say that the `Cacheable` type class is used to decide when we can re-use parts of the schema cache between Metadata operations.
So what is the `Cacheable (Dependency a)` instance about? Normally, the output of a `Rule m a b` is re-used when the new input (of type `a`) is equal to the old one. But sometimes, that's too coarse: it might be that a certain `Rule m a b` only depends on a small part of its input of type `a`. A `Dependency` allows us to spell out what parts of `a` are being depended on, and these parts are recorded as values of types `Access a` in the state `Accesses`.
If the input `a` changes, but not in a way that touches the recorded `Accesses`, then the output `b` of that rule can be re-used without recomputing.
So now you understand _why_ we're passing `Accesses` to the `unchanged` method: `unchanged` is an equality check in disguise that just needs some additional context.
But we don't need to pass `Accesses` as a function argument. We can use the `reflection` package to pass it as type-level context. So the core of this PR is that we change the instance declaration from
```haskell
instance (Cacheable a) => Cacheable (Dependency a) where
```
to
```haskell
instance (Given Accesses, Eq a) => Eq (Dependency a) where
```
and use `(==)` instead of `unchanged`.
If you haven't seen `reflection` before: it's like a `MonadReader`, but it doesn't require a `Monad`.
In order to pass the current `Accesses` value, instead of simply passing the `Accesses` as a function argument, we need to instantiate the `Given Accesses` context. We use the `give` method from the `reflection` package for that.
```haskell
give :: forall r. Accesses -> (Given Accesses => r) -> r
unchanged :: (Given Accesses => Eq a) => Accesses -> a -> a -> Bool
unchanged accesses a b = give accesses (a == b)
```
With these three components in place, we can delete the `Cacheable` type class entirely.
The remainder of this PR is just to remove the `Cacheable` type class and its instances.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6877
GitOrigin-RevId: 7125f5e11d856e7672ab810a23d5bf5ad176e77f
### Description
This monster of a PR took way too long. As the title suggests, it reduces the schema context carried in the readers to the very strict minimum. In practice, that means that to build a source, we only require:
- the global `SchemaContext`
- the global `SchemaOptions` (soon to be renamed `SchemaSourceOptions`)
- that source's `SourceInfo`
Furthermore, _we no longer carry "default" customization options throughout the schema_. All customization information is extracted from the `SourceInfo`, when required. This prevents an entire category of bugs we had previously encountered, such as parts of the code using uninitialized / unupdated customization info.
In turn, this meant that we could remove the explicit threading of the `SourceInfo` throughout the schema, since it is now always available through the reader context.
Finally, this meant making a few adjustments to relay and actions as well, such as the introduction of a new separate "context" for actions, and a change to how we create some of the action-specific postgres scalar parsers.
I'll highlight with review comments the areas of interest.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6709
GitOrigin-RevId: ea80fddcb24e2513779dd04b0b700a55f0028dd1
- Avoid a few banana brackets `(| ... |)`, often by just using local `let` bindings
- Use proper `Arrows` syntax rather than helpers like `>->`
- Use monadic `do` syntax instead of `Arrows` syntax where possible
- Avoid `traverseA @Maybe`, in favor of a `case`
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6751
GitOrigin-RevId: c07b22a1a259db6d135486ec71a716705e280717
`CollectedInfo` was just an awkward sum type. By using an explicit `Either` instead, we can guarantee at the type level that certain methods only write inconsistencies, or only write dependencies. This is useful, because if we can guarantee that no dependencies are written, then we don't need to run `resolveDependencies` on that part of the Metadata. In other words, we can keep it out of `BuildOutputs`, which greatly benefits performance - see e.g. hasura/graphql-engine-mono#6613.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6765
GitOrigin-RevId: 9ce099d2eee2278dbb6e5bea72063e4b6e064b35
A bunch of configurations are retrieved from the Metadata, then stored in the `BuildOutputs` structure, only to then be forwarded to the `SchemaCache`, with extremely little processing in between.
So this simplifies the build pipeline for some parts of the metadata: just construct those things from `Metadata` directly, and store them in the `SchemaCache` without any intermediate container.
Why did we have the detour via `BuildOutputs` in the first place? Parts of the Metadata (codified by `MetadataObjId`) can generate _metadata inconsistencies_ and/or _schema dependencies_, which are related.
- Metadata inconsistencies are warnings that we show to the user, indicating that there's something wrong with their configuration, and they have to fix it.
- Schema dependencies are an internal mechanism that allow us to build a consistent view of the world. For instance, if we have a relationship from DB tables `books` to `authors`, but the `authors` table is inconsistent (e.g. it doesn't exist in the DB), then we have schema dependencies indicating that. The job of `resolveDependencies` is to then drop the relationship, so that we can at least generate a legal GraphQL schema for `books`.
If we never generate a schema dependency for a certain fragment of Metadata, then there is no reason to call `resolveDependencies` on it, and so there is no reason to store it in `BuildOutputs`.
---
The starting point that allows this refactor is to apply Metadata defaults before it reaches `buildAndCollectInfo`, so that metadata-with-defaults can be used elsewhere.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6609
GitOrigin-RevId: df0c4a7ff9451e10e02a40bf26304b26584ba483
This upgrades the version of Ormolu required by the HGE repository to v0.5.0.1, and reformats all code accordingly.
Ormolu v0.5 reformats code that uses infix operators. This is mostly useful, adding newlines and indentation to make it clear which operators are applied first, but in some cases, it's unpleasant. To make this easier on the eyes, I had to do the following:
* Add a few fixity declarations (search for `infix`)
* Add parentheses to make precedence clear, allowing Ormolu to keep everything on one line
* Rename `relevantEq` to `(==~)` in #6651 and set it to `infix 4`
* Add a few _.ormolu_ files (thanks to @hallettj for helping me get started), mostly for Autodocodec operators that don't have explicit fixity declarations
In general, I think these changes are quite reasonable. They mostly affect indentation.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6675
GitOrigin-RevId: cd47d87f1d089fb0bc9dcbbe7798dbceedcd7d83
Ormolu v0.5 tries to reformat code using operators according to fixity. Unfortunately, it doesn't really understand backticked functions (even when they have an associated `infix` declaration), and so messes up the formatting.
This is probably a bug in Ormolu, but we can work around it by using a symbol operator.
Happy to bikeshed on `==~` (which I am reading as "pretty much equal to"). Please yell at me if you prefer something else.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6651
GitOrigin-RevId: 79af427422194460200b2b48339cdb9ee9b33c33
>
## Description
->
This PR allows DC agents to define custom aggregate functions for their scalar types.
### Related Issues
->
GDC-189
### Solution and Design
>
We added a new property `aggregate_functions` to the scalar types capabilities. This allows the agent author to specify a set of aggregate functions supported by each scalar type, along with the function's result type.
During GraphQL schema generation, the custom aggregate functions are available via a new method `getCustomAggregateOperators` on the `Backend` type class.
Custom functions are merged with the builtin aggregate functions when building GraphQL schemas for table aggregate fields and for `order_by` operators on array relations.
### Steps to test and verify
>
• Codec tests for aggregate function capabilities have been added to the unit tests.
• Some custom aggregate operators have been added to the reference agent and are used in a new test in `api-tests`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6199
GitOrigin-RevId: e9c0d1617af93847c1493671fdbb794f573bde0c
The main aim of the PR is:
1. To set up a module structure for 'remote-schemas' package.
2. Move parts by the remote schema codebase into the new module structure to validate it.
## Notes to the reviewer
Why a PR with large-ish diff?
1. We've been making progress on the MM project but we don't yet know long it is going to take us to get to the first milestone. To understand this better, we need to figure out the unknowns as soon as possible. Hence I've taken a stab at the first two items in the [end-state](https://gist.github.com/0x777/ca2bdc4284d21c3eec153b51dea255c9) document to figure out the unknowns. Unsurprisingly, there are a bunch of issues that we haven't discussed earlier. These are documented in the 'open questions' section.
1. The diff is large but that is only code moved around and I've added a section that documents how things are moved. In addition, there are fair number of PR comments to help with the review process.
## Changes in the PR
### Module structure
Sets up the module structure as follows:
```
Hasura/
RemoteSchema/
Metadata/
Types.hs
SchemaCache/
Types.hs
Permission.hs
RemoteRelationship.hs
Build.hs
MetadataAPI/
Types.hs
Execute.hs
```
### 1. Types representing metadata are moved
Types that capture metadata information (currently scattered across several RQL modules) are moved into `Hasura.RemoteSchema.Metadata.Types`.
- This new module only depends on very 'core' modules such as
`Hasura.Session` for the notion of roles and `Hasura.Incremental` for `Cacheable` typeclass.
- The requirement on database modules is avoided by generalizing the remote schemas metadata to accept an arbitrary 'r' for a remote relationship
definition.
### 2. SchemaCache related types and build logic have been moved
Types that represent remote schemas information in SchemaCache are moved into `Hasura.RemoteSchema.SchemaCache.Types`.
Similar to `H.RS.Metadata.Types`, this module depends on 'core' modules except for `Hasura.GraphQL.Parser.Variable`. It has something to do with remote relationships but I haven't spent time looking into it. The validation of 'remote relationships to remote schema' is also something that needs to be looked at.
Rips out the logic that builds remote schema's SchemaCache information from the monolithic `buildSchemaCacheRule` and moves it into `Hasura.RemoteSchema.SchemaCache.Build`. Further, the `.SchemaCache.Permission` and `.SchemaCache.RemoteRelationship` have been created from existing modules that capture schema cache building logic for those two components.
This was a fair amount of work. On main, currently remote schema's SchemaCache information is built in two phases - in the first phase, 'permissions' and 'remote relationships' are ignored and in the second phase they are filled in.
While remote relationships can only be resolved after partially resolving sources and other remote schemas, the same isn't true for permissions. Further, most of the work that is done to resolve remote relationships can be moved to the first phase so that the second phase can be a very simple traversal.
This is the approach that was taken - resolve permissions and as much as remote relationships information in the first phase.
### 3. Metadata APIs related types and build logic have been moved
The types that represent remote schema related metadata APIs and the execution logic have been moved to `Hasura.RemoteSchema.MetadataAPI.Types` and `.Execute` modules respectively.
## Open questions:
1. `Hasura.RemoteSchema.Metadata.Types` is so called because I was hoping that all of the metadata related APIs of remote schema can be brought in at `Hasura.RemoteSchema.Metadata.API`. However, as metadata APIs depended on functions from `SchemaCache` module (see [1](ceba6d6226/server/src-lib/Hasura/RQL/DDL/RemoteSchema.hs (L55)) and [2](ceba6d6226/server/src-lib/Hasura/RQL/DDL/RemoteSchema.hs (L91)), it made more sense to create a separate top-level module for `MetadataAPI`s.
Maybe we can just have `Hasura.RemoteSchema.Metadata` and get rid of the extra nesting or have `Hasura.RemoteSchema.Metadata.{Core,Permission,RemoteRelationship}` if we want to break them down further.
1. `buildRemoteSchemas` in `H.RS.SchemaCache.Build` has the following type:
```haskell
buildRemoteSchemas ::
( ArrowChoice arr,
Inc.ArrowDistribute arr,
ArrowWriter (Seq CollectedInfo) arr,
Inc.ArrowCache m arr,
MonadIO m,
HasHttpManagerM m,
Inc.Cacheable remoteRelationshipDefinition,
ToJSON remoteRelationshipDefinition,
MonadError QErr m
) =>
Env.Environment ->
( (Inc.Dependency (HashMap RemoteSchemaName Inc.InvalidationKey), OrderedRoles),
[RemoteSchemaMetadataG remoteRelationshipDefinition]
)
`arr` HashMap RemoteSchemaName (PartiallyResolvedRemoteSchemaCtxG remoteRelationshipDefinition, MetadataObject)
```
Note the dependence on `CollectedInfo` which is defined as
```haskell
data CollectedInfo
= CIInconsistency InconsistentMetadata
| CIDependency
MetadataObject
-- ^ for error reporting on missing dependencies
SchemaObjId
SchemaDependency
deriving (Eq)
```
this pretty much means that remote schemas is dependent on types from databases, actions, ....
How do we fix this? Maybe introduce a typeclass such as `ArrowCollectRemoteSchemaDependencies` which is defined in `Hasura.RemoteSchema` and then implemented in graphql-engine?
1. The dependency on `buildSchemaCacheFor` in `.MetadataAPI.Execute` which has the following signature:
```haskell
buildSchemaCacheFor ::
(QErrM m, CacheRWM m, MetadataM m) =>
MetadataObjId ->
MetadataModifier ->
```
This can be easily resolved if we restrict what the metadata APIs are allowed to do. Currently, they operate in an unfettered access to modify SchemaCache (the `CacheRWM` constraint):
```haskell
runAddRemoteSchema ::
( QErrM m,
CacheRWM m,
MonadIO m,
HasHttpManagerM m,
MetadataM m,
Tracing.MonadTrace m
) =>
Env.Environment ->
AddRemoteSchemaQuery ->
m EncJSON
```
This should instead be changed to restrict remote schema APIs to only modify remote schema metadata (but has access to the remote schemas part of the schema cache), this dependency is completely removed.
```haskell
runAddRemoteSchema ::
( QErrM m,
MonadIO m,
HasHttpManagerM m,
MonadReader RemoteSchemasSchemaCache m,
MonadState RemoteSchemaMetadata m,
Tracing.MonadTrace m
) =>
Env.Environment ->
AddRemoteSchemaQuery ->
m RemoteSchemeMetadataObjId
```
The idea is that the core graphql-engine would call these functions and then call
`buildSchemaCacheFor`.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6291
GitOrigin-RevId: 51357148c6404afe70219afa71bd1d59bdf4ffc6
