feat(config): specify to use in-memory database

[yshngg]

Add support for specifying database type (MongoDB or in-memory database).

Motivation and Context

The README states that MCP Registry supports both MongoDB and in-memory databases, but does not provide the capability to specify which database type to use.

registry/README.md

Line 19 in 5d9171b

- MongoDB and in-memory database support

This PR addresses this limitation by adding explicit database type configuration through the DATABASE_TYPE environment variable, allowing users to choose between mongodb and memory database types in a standardized way.

How Has This Been Tested?

Yes

$ export MCP_REGISTRY_DATABASE_TYPE="memory"
$ ./scripts/test_endpoints.sh
Testing health endpoint: http://localhost:8080/v0/health
Status Code: 200
Response:
{
  "status": "ok",
  "github_client_id": ""
}
Health check successful
-------------------------------------
Testing servers endpoint: http://localhost:8080/v0/servers
Status Code: 200
Response Summary:
Total registries: 0
servers Names:

Pagination Metadata:
{}

servers Details:
{
  "servers": [],
  "metadata": {}
}
servers request successful
-------------------------------------
Testing ping endpoint: http://localhost:8080/v0/ping
Status Code: 200
Response:
{
  "status": "ok",
  "version": "dev"
}
Ping successful
-------------------------------------
All tests passed successfully!

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Close #63

[sridharavinash]

👋🏾 thanks for contributing! Once the merge conflicts are resolved and checks are passing, I'd be happy to merge this in. 🙇🏾

[yshngg]

Hey @sridharavinash , thanks for your reply! Review please.

[Copilot]

Pull Request Overview

Add support for selecting either MongoDB or an in-memory database via a new DATABASE_TYPE configuration.

• Introduces a DatabaseType enum in Config with a default of "mongodb"
• Updates main.go to initialize either MongoDB or memory-backed storage based on cfg.DatabaseType
• Documents the new environment variable in README.md

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
internal/config/config.go	Defined DatabaseType constants and added a DatabaseType field
cmd/registry/main.go	Switched database initialization based on cfg.DatabaseType
README.md	Documented the MCP_REGISTRY_DATABASE_TYPE environment variable

Comments suppressed due to low confidence (2)

README.md:292

• The README documents MCP_REGISTRY_DATABASE_TYPE, but the code is reading DATABASE_TYPE. Update either the code or the docs so they stay in sync.

| `MCP_REGISTRY_DATABASE_TYPE`         | Database type | `mongodb` |

cmd/registry/main.go:43

• The new in-memory database branch isn’t covered by any existing tests. Consider adding unit or integration tests to verify behavior when DATABASE_TYPE=memory.

switch cfg.DatabaseType {

[sridharavinash]

Thanks for adding this ✨ ! 🙇🏾

[maorfr]

thank you all for this great and timely work ❤️
i've created a follow up item: #129