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Posted to notifications@superset.apache.org by "geovanasullivan (via GitHub)" <gi...@apache.org> on 2026/10/19 13:58:58 UTC
[D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
GitHub user geovanasullivan created a discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
Version: Apache Superset 6.1.0. MCP started with superset mcp run, MCP_AUTH_ENABLED=True, JWT validation.
What I expected: following the MCP server docs, the sub claim of the token identifies the Superset user, so each person’s RBAC applies.
What happens: the JWT is validated, but nothing maps sub to a Superset user. Every tool call fails with “No authenticated user found” unless I set MCP_DEV_USERNAME. With it set, every token acts as the same user, so there is no per-user RBAC or auditing.
Docs vs code: the docs mention MCP_USER_RESOLVER. I searched the repository for it and found no results.
Questions:
- Does MCP_USER_RESOLVER exist? If so, in which release (or branch) is it available?
- Is there a supported way in 6.1.0 to map the token identity to a Superset user?
- What is the recommended setup for multi-user access until then? (We would like to avoid everyone acting as a single shared user.)
@dosu
GitHub link: https://github.com/apache/superset/discussions/45457
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "aymansalkhatib (via GitHub)" <gi...@apache.org>.
GitHub user aymansalkhatib added a comment to the discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
Short answer: `MCP_USER_RESOLVER` exists, but **not in the 6.1.0 code**. The 6.1.0 docs describe a feature that only ships from **7.0** onward (it's in `7.0.0rc1` and `7.0.0rc2`). That's why you see JWT validation succeed and then "No authenticated user found".
### What 6.1.0 actually does
In the [6.1.0 `auth.py`](https://github.com/apache/superset/blob/6.1.0/superset/mcp_service/auth.py), `get_user_from_request()` only tries two sources:
1. `g.user`, if something already set it ("Preset workspace middleware", per the docstring);
2. `MCP_DEV_USERNAME`.
Nothing reads the validated token's claims. `mcp_config.py` in 6.1.0 does define a `default_user_resolver()`, but `auth.py` never calls it, and `MCP_USER_RESOLVER` isn't referenced anywhere in that tag. So the JWT gets through the transport layer, no user is derived from it, and every call ends up either failing or running as the single `MCP_DEV_USERNAME` user. That matches what you describe.
### Where it was added
On `master`, `auth.py` gained `_resolve_user_from_jwt_context()`, first in [#38747](https://github.com/apache/superset/pull/38747), with follow-ups such as #39106 and #39385. It reads the token through FastMCP's `get_access_token()` and calls:
```python
resolver = app.config.get("MCP_USER_RESOLVER", default_user_resolver)
username = resolver(app, access_token)
```
The [default resolver](https://github.com/apache/superset/blob/master/superset/mcp_service/mcp_config.py) checks `preferred_username`, then `username`, `email`, `sub`. The result is looked up as a Superset username, with an email fallback when it contains `@`. It **fails closed**: if the user doesn't exist, or the token has no usable claim, the call is denied and there's no fallback to `MCP_DEV_USERNAME`. Deactivated accounts are also refused.
### Mapping `sub` on 7.0
If your IdP's `sub` is an opaque ID, a custom resolver can return the Superset username yourself:
```python
# superset_config.py
def resolve_mcp_user(app, access_token):
claims = getattr(access_token, "claims", None) or {}
return claims.get("preferred_username") or claims.get("email")
MCP_USER_RESOLVER = resolve_mcp_user
```
Users still have to exist in Superset beforehand; the resolver doesn't create them. If `MCP_JWT_ISSUER` trusts **more than one issuer**, 7.0 refuses to start without an issuer-aware resolver ([#42935](https://github.com/apache/superset/pull/42935), see `UPDATING.md`). In that case, include the `iss` claim in the identity you return.
### Until you can run 7.0
- **Test `7.0.0rc2`** in staging if you can. It contains the code above, and it's what the docs are describing.
- On 6.1.0 there's no supported per-user mapping. The least-bad interim setup is **one MCP server instance per access level**, each with its own `MCP_DEV_USERNAME` pointing to a dedicated, least-privileged service account (for example `mcp_readonly_sales`, `mcp_readonly_finance`), with JWT auth kept on so only the right clients can reach each instance. You get role-level RBAC this way, but not per-person auditing.
- If you need 6.1.x specifically, ask the maintainers about backporting #38747 and its follow-ups. It touches the auth path, so I wouldn't patch it locally.
GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19065575
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "dosubot[bot] (via GitHub)" <gi...@apache.org>.
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GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19041737
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "FrancescoCastaldi (via GitHub)" <gi...@apache.org>.
GitHub user FrancescoCastaldi added a comment to the discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
To answer your questions directly:
1. **Does `MCP_USER_RESOLVER` exist?**
Yes, but it was introduced in pull request #38747 for the Superset 7.0 development cycle (`master` and 7.0 release candidates). In the 6.1.0 release tag, `superset/mcp_service/auth.py` only implements authentication via `g.user` or fallback to `MCP_DEV_USERNAME`. The documentation was updated ahead of the code backport.
2. **Is there a supported way in 6.1.0 to map token identity without upgrading?**
In 6.1.0 there is no native configuration key for user resolution. However, you can inject the resolver dynamically in `superset_config.py` by monkeypatching the MCP authentication function during startup:
```python
# superset_config.py
from superset.extensions import security_manager
from flask import g
def patch_mcp_auth():
try:
import superset.mcp_service.auth as mcp_auth
original_get_user = mcp_auth.get_user_from_request
def custom_get_user_from_request():
user = original_get_user()
if user:
return user
# Extract JWT from Authorization header
from fastmcp.server.dependencies import get_access_token
token = get_access_token()
if token and hasattr(token, "claims"):
username = token.claims.get("preferred_username") or token.claims.get("sub")
if username:
resolved_user = security_manager.find_user(username=username)
if resolved_user:
return resolved_user
return None
mcp_auth.get_user_from_request = custom_get_user_from_request
except (ImportError, AttributeError):
pass
# Execute during config evaluation
patch_mcp_auth()
```
3. **Recommended Multi-User Setup:**
If you cannot patch 6.1.0 or upgrade to the 7.0 release line:
- Keep `MCP_DEV_USERNAME = None` in production environments to avoid privilege escalation.
- Run the MCP server behind an API gateway or reverse proxy that validates the user session and proxies requests with user context.
- When migrating to 7.0, configure the native `MCP_USER_RESOLVER` function in `superset_config.py` taking `(app, access_token)` and returning the corresponding username from your directory.
GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19164445
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "nicholas-greenwood (via GitHub)" <gi...@apache.org>.
GitHub user nicholas-greenwood added a comment to the discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
your 6.1.0 result matches the tagged code. the docs list `MCP_USER_RESOLVER`, but [6.1.0's `get_user_from_request()`](https://github.com/apache/superset/blob/6.1.0/superset/mcp_service/auth.py#L176-L230) only checks an existing `g.user` and `MCP_DEV_USERNAME`. adding a resolver to `superset_config.py` won't connect the validated jwt to a user in that version
that connection was added in [#38747](https://github.com/apache/superset/pull/38747). `MCP_USER_RESOLVER` is used on `master` and in [7.0.0rc2's auth code](https://github.com/apache/superset/blob/7.0.0rc2/superset/mcp_service/auth.py#L560-L690). [7.0.0rc2 is a prerelease](https://github.com/apache/superset/releases/tag/7.0.0rc2), so i'd test it in staging before considering an upgrade
in that implementation, `MCP_USER_RESOLVER(app, access_token)` returns an existing superset username. the [default resolver](https://github.com/apache/superset/blob/7.0.0rc2/superset/mcp_service/mcp_config.py#L839-L870) checks `preferred_username`, `username`, `email`, then `sub`. an opaque `sub` therefore needs an explicit mapping if it doesn't match your superset usernames. users must already exist, and an unknown identity is rejected
for multi-user access, use that per-request identity path with `MCP_DEV_USERNAME` unset, `MCP_RBAC_ENABLED = True`, and jwt validation bound to your issuer and mcp audience. if you trust multiple issuers, the custom mapping needs to use both `iss` and `sub` so 2 issuers can't resolve the same subject to the wrong account. check with 2 users who have different dataset permissions, including concurrent calls, and confirm their audit user ids before exposing it
if you need to stay on stable 6.1.0, i'm afraid there is no configuration-only fix in its native mcp path. i'd keep multi-user mcp disabled until you have a reviewed backport or a stable release containing the resolver. `MCP_DEV_USERNAME` would keep everyone acting as the same user
cheers
GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19042562
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "nicholas-greenwood (via GitHub)" <gi...@apache.org>.
GitHub user nicholas-greenwood edited a comment on the discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
the docs list `MCP_USER_RESOLVER`, but it is not wired up in 6.1.0. [6.1.0's `get_user_from_request()`](https://github.com/apache/superset/blob/6.1.0/superset/mcp_service/auth.py#L176-L230) only checks an existing `g.user` and `MCP_DEV_USERNAME`. adding a resolver to `superset_config.py` won't connect the validated jwt to a user in that version
the resolver was added in [#38747](https://github.com/apache/superset/pull/38747). `MCP_USER_RESOLVER` is used on `master` and in [7.0.0rc2's auth code](https://github.com/apache/superset/blob/7.0.0rc2/superset/mcp_service/auth.py#L560-L690). [7.0.0rc2 is a prerelease](https://github.com/apache/superset/releases/tag/7.0.0rc2), so i'd test it in staging before considering an upgrade
in that implementation, `MCP_USER_RESOLVER(app, access_token)` returns an existing superset username. the [default resolver](https://github.com/apache/superset/blob/7.0.0rc2/superset/mcp_service/mcp_config.py#L839-L870) checks `preferred_username`, `username`, `email`, then `sub`. if an opaque `sub` doesn't match your superset usernames, you'll need an explicit mapping
the users must already exist. unknown identities are rejected
for multi-user access:
- leave `MCP_DEV_USERNAME` unset
- set `MCP_RBAC_ENABLED = True`
- bind jwt validation to your issuer and mcp audience
if you trust multiple issuers, map using both `iss` and `sub`. otherwise, 2 issuers could resolve the same subject to the wrong account
before exposing the service, test with 2 users who have different dataset permissions. include concurrent calls and check their audit user ids
if you need to stay on stable 6.1.0, i'm afraid there's no configuration-only fix for multi-user identity in its mcp authentication code. i'd keep multi-user mcp disabled until you have a reviewed backport or a stable release containing the resolver. `MCP_DEV_USERNAME` would keep everyone acting as the same user
cheers
GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19042562
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Re: [D] MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code) [superset]
Posted by "aymansalkhatib (via GitHub)" <gi...@apache.org>.
GitHub user aymansalkhatib deleted a comment on the discussion: MCP server: how to map the JWT identity to a Superset user? (MCP_USER_RESOLVER in docs, not found in code)
Short answer: `MCP_USER_RESOLVER` exists, but **not in the 6.1.0 code**. The 6.1.0 docs describe a feature that only ships from **7.0** onward (it's in `7.0.0rc1` and `7.0.0rc2`). That's why you see JWT validation succeed and then "No authenticated user found".
### What 6.1.0 actually does
In the [6.1.0 `auth.py`](https://github.com/apache/superset/blob/6.1.0/superset/mcp_service/auth.py), `get_user_from_request()` only tries two sources:
1. `g.user`, if something already set it ("Preset workspace middleware", per the docstring);
2. `MCP_DEV_USERNAME`.
Nothing reads the validated token's claims. `mcp_config.py` in 6.1.0 does define a `default_user_resolver()`, but `auth.py` never calls it, and `MCP_USER_RESOLVER` isn't referenced anywhere in that tag. So the JWT gets through the transport layer, no user is derived from it, and every call ends up either failing or running as the single `MCP_DEV_USERNAME` user. That matches what you describe.
### Where it was added
On `master`, `auth.py` gained `_resolve_user_from_jwt_context()`, first in [#38747](https://github.com/apache/superset/pull/38747), with follow-ups such as #39106 and #39385. It reads the token through FastMCP's `get_access_token()` and calls:
```python
resolver = app.config.get("MCP_USER_RESOLVER", default_user_resolver)
username = resolver(app, access_token)
```
The [default resolver](https://github.com/apache/superset/blob/master/superset/mcp_service/mcp_config.py) checks `preferred_username`, then `username`, `email`, `sub`. The result is looked up as a Superset username, with an email fallback when it contains `@`. It **fails closed**: if the user doesn't exist, or the token has no usable claim, the call is denied and there's no fallback to `MCP_DEV_USERNAME`. Deactivated accounts are also refused.
### Mapping `sub` on 7.0
If your IdP's `sub` is an opaque ID, a custom resolver can return the Superset username yourself:
```python
# superset_config.py
def resolve_mcp_user(app, access_token):
claims = getattr(access_token, "claims", None) or {}
return claims.get("preferred_username") or claims.get("email")
MCP_USER_RESOLVER = resolve_mcp_user
```
Users still have to exist in Superset beforehand; the resolver doesn't create them. If `MCP_JWT_ISSUER` trusts **more than one issuer**, 7.0 refuses to start without an issuer-aware resolver ([#42935](https://github.com/apache/superset/pull/42935), see `UPDATING.md`). In that case, include the `iss` claim in the identity you return.
### Until you can run 7.0
- **Test `7.0.0rc2`** in staging if you can. It contains the code above, and it's what the docs are describing.
- On 6.1.0 there's no supported per-user mapping. The least-bad interim setup is **one MCP server instance per access level**, each with its own `MCP_DEV_USERNAME` pointing to a dedicated, least-privileged service account (for example `mcp_readonly_sales`, `mcp_readonly_finance`), with JWT auth kept on so only the right clients can reach each instance. You get role-level RBAC this way, but not per-person auditing.
- If you need 6.1.x specifically, ask the maintainers about backporting #38747 and its follow-ups. It touches the auth path, so I wouldn't patch it locally.
GitHub link: https://github.com/apache/superset/discussions/45457#discussioncomment-19065575
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