feat: auto add MCP projects servers with auth API key mode #9891
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Important Review skippedAuto incremental reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the You can disable this status message by setting the WalkthroughImplements settings to record the actual server port, refactors MCP project utilities (host/port/SSE URL resolution and config path retrieval), adds project-scoped MCP handler methods, and auto-registers MCP servers upon project creation when enabled by settings. Changes
Sequence Diagram(s)sequenceDiagram
autonumber
actor User
participant CLI as CLI/Entrypoint
participant Server as Langflow Server
participant Settings as SettingsService
User->>CLI: Start server (port P requested)
CLI->>Server: Resolve available port (may adjust P)
Server-->>CLI: Final port = PF
CLI->>Settings: settings.current_port = PF
Note right of Settings: Records actual listening port
CLI->>Server: Continue startup (protocol, DB, routes)
Server-->>User: Server ready on host:PF
sequenceDiagram
autonumber
actor Client as API Client
participant API as Projects API
participant Settings as SettingsService
participant Keys as API Key Service
participant MCP as MCP Registry
participant SSE as get_project_sse_url
Client->>API: Create project
API-->>Client: Project created
API->>Settings: Check add_projects_to_mcp_servers
alt Enabled
API->>Keys: Create API key
API->>API: Encrypt project auth settings (API key)
API->>SSE: Compute project SSE URL (host/port via settings.current_port)
API->>MCP: update_server(name, command, env/headers incl. API key & SSE URL)
MCP-->>API: Registered/updated
else Disabled
Note over API: Skip MCP registration
end
sequenceDiagram
autonumber
actor MCPClient as MCP Client
participant ProjectSrv as ProjectMCPServer
participant Core as Core Handlers
MCPClient->>ProjectSrv: listTools/readResource/callTool (project-scoped)
ProjectSrv->>Core: Delegate to existing handlers with project_id
Core-->>ProjectSrv: Results
ProjectSrv-->>MCPClient: Response
Estimated code review effort🎯 4 (Complex) | ⏱️ ~60 minutes Possibly related PRs
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Actionable comments posted: 1
🧹 Nitpick comments (3)
src/lfx/src/lfx/services/settings/base.py (1)
217-218: Make current_port ephemeral (avoid persisting to YAML).current_port is runtime-only. Exclude it from model_dump to prevent leaking transient state into saved configs.
- current_port: int | None = None + current_port: int | None = Field(default=None, exclude=True)src/backend/base/langflow/api/v1/projects.py (1)
86-125: Auto‑register MCP servers: tweak server name length and consider backgrounding.
- Off‑by‑one in truncation: subtract len('lf-') so the total length respects MAX_MCP_SERVER_NAME_LENGTH exactly.
- Optional: run the registration in a background task to avoid adding latency to project creation (keep current try/except).
- server_name = f"lf-{sanitize_mcp_name(new_project.name)[: (MAX_MCP_SERVER_NAME_LENGTH - 4)]}" + server_name = f"lf-{sanitize_mcp_name(new_project.name)[: (MAX_MCP_SERVER_NAME_LENGTH - len('lf-'))]}"src/backend/base/langflow/api/v1/mcp_projects.py (1)
894-904: Prefer https in SSE URL when TLS is enabled.get_project_sse_url always builds http://…, which breaks when running with cert/key. Detect TLS from settings and set the scheme.
- base_url = f"http://{host}:{port}".rstrip("/") + protocol = "https" if getattr(settings_service.settings, "ssl_cert_file", None) and getattr( + settings_service.settings, "ssl_key_file", None + ) else "http" + base_url = f"{protocol}://{host}:{port}".rstrip("/")
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📒 Files selected for processing (4)
src/backend/base/langflow/__main__.py(1 hunks)src/backend/base/langflow/api/v1/mcp_projects.py(3 hunks)src/backend/base/langflow/api/v1/projects.py(3 hunks)src/lfx/src/lfx/services/settings/base.py(2 hunks)
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{src/backend/**/*.py,tests/**/*.py,Makefile}
📄 CodeRabbit inference engine (.cursor/rules/backend_development.mdc)
{src/backend/**/*.py,tests/**/*.py,Makefile}: Run make format_backend to format Python code before linting or committing changes
Run make lint to perform linting checks on backend Python code
Files:
src/backend/base/langflow/__main__.pysrc/backend/base/langflow/api/v1/projects.pysrc/backend/base/langflow/api/v1/mcp_projects.py
🧠 Learnings (2)
📓 Common learnings
Learnt from: deon-sanchez
PR: langflow-ai/langflow#9158
File: src/backend/base/langflow/api/v1/mcp_projects.py:404-404
Timestamp: 2025-07-23T21:19:22.567Z
Learning: In langflow MCP projects configuration, prefer using dynamically computed URLs (like the `sse_url` variable) over hardcoded localhost URLs to ensure compatibility across different deployment environments.
📚 Learning: 2025-07-23T21:19:22.567Z
Learnt from: deon-sanchez
PR: langflow-ai/langflow#9158
File: src/backend/base/langflow/api/v1/mcp_projects.py:404-404
Timestamp: 2025-07-23T21:19:22.567Z
Learning: In langflow MCP projects configuration, prefer using dynamically computed URLs (like the `sse_url` variable) over hardcoded localhost URLs to ensure compatibility across different deployment environments.
Applied to files:
src/backend/base/langflow/api/v1/mcp_projects.py
🧬 Code graph analysis (3)
src/backend/base/langflow/__main__.py (1)
src/backend/base/langflow/services/deps.py (1)
get_settings_service(111-124)
src/backend/base/langflow/api/v1/projects.py (7)
src/frontend/src/constants/constants.ts (1)
MAX_MCP_SERVER_NAME_LENGTH(562-562)src/backend/base/langflow/api/v1/mcp_projects.py (1)
get_project_sse_url(890-930)src/backend/base/langflow/api/v2/mcp.py (1)
update_server(201-245)src/backend/base/langflow/services/auth/mcp_encryption.py (1)
encrypt_auth_settings(18-51)src/backend/base/langflow/services/database/models/api_key/crud.py (1)
create_api_key(24-40)src/backend/base/langflow/services/database/models/api_key/model.py (1)
ApiKeyCreate(39-47)src/backend/base/langflow/services/deps.py (2)
get_settings_service(111-124)get_storage_service(88-96)
src/backend/base/langflow/api/v1/mcp_projects.py (1)
src/backend/tests/unit/api/v2/test_mcp_servers_file.py (1)
settings_service(95-96)
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🔇 Additional comments (4)
src/lfx/src/lfx/services/settings/base.py (1)
268-272: LGTM: feature flag is clear and env‑wired.Consider adding this to the user‑visible settings docs/ENV list so operators know about LANGFLOW_ADD_PROJECTS_TO_MCP_SERVERS.
src/backend/base/langflow/api/v1/projects.py (1)
15-17: Imports for MCP auto‑registration look correct.No issues spotted with symbol locations or dependency direction.
Also applies to: 24-24, 26-26, 30-33, 43-43
src/backend/base/langflow/api/v1/mcp_projects.py (2)
51-53: LGTM: centralized ALL_INTERFACES_HOST.Good replacement for hardcoded "0.0.0.0".
454-456: LGTM: use ALL_INTERFACES_HOST in local IP check.Keeps logic consistent and readable.
| # Store the actual port being used in settings | ||
| get_settings_service().settings.current_port = port | ||
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Fix port propagation across processes (spawn) to avoid wrong SSE URLs.
When the configured port is occupied and a free one is chosen, only current_port is set in the parent. On macOS (spawn) and some setups, workers may not see this and fall back to stale settings.port, producing bad SSE URLs in MCP configs.
Apply both assignments (and export env) before starting the server:
- # Store the actual port being used in settings
- get_settings_service().settings.current_port = port
+ # Store the actual port being used in settings (propagate to workers/spawned processes)
+ settings_service = get_settings_service()
+ settings_service.settings.current_port = port
+ settings_service.settings.port = port
+ os.environ["LANGFLOW_PORT"] = str(port)📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| # Store the actual port being used in settings | |
| get_settings_service().settings.current_port = port | |
| # Store the actual port being used in settings (propagate to workers/spawned processes) | |
| settings_service = get_settings_service() | |
| settings_service.settings.current_port = port | |
| settings_service.settings.port = port | |
| os.environ["LANGFLOW_PORT"] = str(port) |
🤖 Prompt for AI Agents
In src/backend/base/langflow/__main__.py around lines 344 to 346, when the
chosen port differs from the configured one only current_port is set, causing
spawned worker processes to see stale settings.port and produce wrong SSE URLs;
set both get_settings_service().settings.port and
get_settings_service().settings.current_port to the chosen port and export it to
the environment (e.g., os.environ["PORT"] = str(port)) before starting the
server so child processes inherit the correct port.
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## main #9891 +/- ##
==========================================
+ Coverage 22.86% 23.00% +0.13%
==========================================
Files 1085 1085
Lines 39733 39866 +133
Branches 5420 5420
==========================================
+ Hits 9084 9170 +86
- Misses 30494 30541 +47
Partials 155 155
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This pull request introduces enhancements to the project creation workflow and server configuration management, focusing on automatic MCP server registration for new projects, improved handling of server port settings, and better code maintainability. The changes ensure that new projects are more seamlessly integrated into the MCP ecosystem, with secure API key authentication and accurate server connection details.
Project creation & MCP server integration:
add_projects_to_mcp_serversis enabled, including secure API key generation, encrypted authentication settings, and server configuration updates in the user's_mcp_servers.jsonfile.add_projects_to_mcp_serverssetting toSettings, allowing control over automatic MCP server registration via environment variable.Server port and connection management:
current_portto theSettingsmodel to track the actual port Langflow is running on after resolving conflicts.settings.current_portafter checking for port availability.current_portif available, and always substitutes0.0.0.0withlocalhostfor client connections to avoid bind/connect confusion.Code maintainability and clarity:
ALL_INTERFACES_HOST(0.0.0.0) for clarity and replaces hardcoded values in IP checks and host selection logic. [1] [2]get_project_sse_url,update_server, and utility functions for MCP server management. [1] [2]Summary by CodeRabbit
New Features
Bug Fixes