gRPC Connectors API

[twoojoo]

Overview

I added gRPC API support for connectors (CRUD operations)

What this PR does / why we need it

I think it could be useful to have the possibility of handling connectors dynamically without the need to restart Dex.

Special notes for your reviewer

• added a Config.Parse() function to prevent AdditionalFeatures field from being nil (default = empty slice)
• added a list of ValidAdditionalFeaturs to prevent invalid features from being provided and making detecting typos easier
• addtionalFeatures slice is passed down to the API struct, so new features that affect apis can be easily added

Does this PR introduce a user-facing change?

It adds connectors functions and types to the gRPC client, but it shouldn't break anything.

- Implemented additionalFeatures config entry (list)
- Implemented ConnectorsCRUD as additional feature
- Updated examples/config.dev.yaml file 
- Added gRPC API support for connectors CRUD operations
- Missing ConnectorsCRUD in additionalFeatures in config file will cause connectors gRPC functions to return an error
- Connectors configs are of the bytes type in .proto file and are checked for JSON validity when inserting and updating a connector
- All fields (id, name, type, config) are mandatory when inserting a new connector

[twoojoo]

hi @nabokihms, this time it should pass. I tried running that workflow in a separate branch.

[nabokihms]

My only concern regarding this PR is that we extend capabilities for existing API servers. So users who can control oauth2 clients can now control connectors also.

[twoojoo]

I think that it won't affect a standard usage of Dex (at least from what I know about it), but I totally understand your concern. Wouldn't increasing the minor version be sufficient as a way to alert developers? After all, it's a backward-compatible change, although it depends on what is meant by "backward compatibility."

[twoojoo]

Could adding an 'allowEditConnectors' (false if missing) in the grpc section of the config file be a solution? Connectors API functions would still be there, but would return an error when called when that config entry is false.

[nabokihms]

Yeah, something like that will work. I assume it is better to make it the list of features instead of a boolean flag, e.g., additionalFeatures: ["ConnectorsCRUD"].

In the future, we will be able to extend the API server with more features.

[twoojoo]

hi @nabokihms , is there any way I could help move the PR forward? I am available to correct any inaccuracies or to add any missing elements