rusackas commented on code in PR #43637:
URL: https://github.com/apache/superset/pull/43637#discussion_r3886453365
##########
docs/admin_docs/configuration/mcp-server.mdx:
##########
@@ -253,6 +253,57 @@ def my_custom_auth_factory(app):
MCP_AUTH_FACTORY = my_custom_auth_factory
```
+### Embedded Guest Authentication
+
+Superset's [embedded dashboards](/user-docs/using-superset/embedding) feature
mints short-lived **guest tokens** for anonymous/embedded viewers. The MCP
server can accept these same guest tokens, so an embedded guest (e.g. an in-app
chatbot next to an embedded dashboard) can call MCP tools scoped to the
dashboards/resources named in its token.
+
+This is opt-in and reuses the existing core guest-token configuration -- there
is no MCP-specific guest secret or audience.
+
+```python
+# superset_config.py
+FEATURE_FLAGS = {"EMBEDDED_SUPERSET": True} # required -- guest tokens only
exist when this is on
+MCP_EMBEDDED_GUEST_AUTH_ENABLED = True # opt-in for the MCP transport
(default False)
Review Comment:
Good catch, added a note that a configured `MCP_AUTH_FACTORY` skips the
default factory (and the guest verifier) entirely, so a custom factory needs to
handle guest tokens itself.
##########
docs/admin_docs/configuration/mcp-server.mdx:
##########
@@ -253,6 +253,57 @@ def my_custom_auth_factory(app):
MCP_AUTH_FACTORY = my_custom_auth_factory
```
+### Embedded Guest Authentication
+
+Superset's [embedded dashboards](/user-docs/using-superset/embedding) feature
mints short-lived **guest tokens** for anonymous/embedded viewers. The MCP
server can accept these same guest tokens, so an embedded guest (e.g. an in-app
chatbot next to an embedded dashboard) can call MCP tools scoped to the
dashboards/resources named in its token.
+
+This is opt-in and reuses the existing core guest-token configuration -- there
is no MCP-specific guest secret or audience.
+
+```python
+# superset_config.py
+FEATURE_FLAGS = {"EMBEDDED_SUPERSET": True} # required -- guest tokens only
exist when this is on
+MCP_EMBEDDED_GUEST_AUTH_ENABLED = True # opt-in for the MCP transport
(default False)
+```
+
+Present the guest token the same way as any other bearer token:
+
+```bash
+curl -X POST http://localhost:5008/mcp \
+ -H 'Content-Type: application/json' \
+ -H 'Authorization: Bearer YOUR_GUEST_TOKEN' \
+ -d '{"jsonrpc": "2.0", "method": "tools/list", "id": 1}'
+```
+
+**How it works**
+
+- A dedicated guest-token verifier validates the token against the same
`GUEST_TOKEN_JWT_SECRET` / `GUEST_TOKEN_JWT_ALGO` / `GUEST_TOKEN_JWT_AUDIENCE`
config used by embedded dashboards, replays the embedded structural checks, and
enforces revocation (global version bumps and per-dashboard
`guest_token_revoked_before` cutoffs). It runs *before* the JWT verifier
described above, since guest tokens are signed with a different key/algorithm
and would otherwise be rejected at the transport.
+- A verified guest resolves to a Superset guest user as the highest-priority
identity, so it's never downgraded to API-key / `MCP_DEV_USERNAME` / dev-mode
resolution. Data access is scoped by the same checks (dataset allowlist,
dashboard access, row-level security) that apply to embedded dashboard views.
+- Guests are restricted to a default-deny allow-list,
`MCP_GUEST_ALLOWED_TOOLS`, regardless of `MCP_RBAC_ENABLED`. Sensitive
enumeration tools like `find_users` and `get_instance_info` are denied simply
by being absent from the default list.
+
+```python
+# superset_config.py
+MCP_GUEST_ALLOWED_TOOLS = {
+ "get_dashboard_info",
+ "get_dashboard_layout",
+ "list_dashboards",
+ "list_charts",
+ "get_chart_info",
+ "get_chart_data",
+ "get_chart_preview",
+} # default
+```
+
+**Deployment requirements**
+
+- The MCP server and the service that mints guest tokens (the Superset web
app) must share `GUEST_TOKEN_JWT_SECRET` and `GUEST_TOKEN_JWT_AUDIENCE`. Set
`GUEST_TOKEN_JWT_AUDIENCE` explicitly -- if it's unset, audience validation
falls back to the URL host, which can differ between the two services and cause
every guest token to fail validation.
+- The `GUEST_ROLE_NAME` role (default `Public`) must exist -- a guest token is
rejected if it does not.
+- Don't set `MCP_DEV_USERNAME` on a deployment that also serves embedded
guests.
+- Restart the MCP process after toggling `EMBEDDED_SUPERSET` or
`MCP_EMBEDDED_GUEST_AUTH_ENABLED` -- guest auth is wired up once at startup.
+
+:::warning
+`GUEST_TOKEN_JWT_SECRET` guards both the web embedding and MCP guest-auth
surfaces. Never leave it at its insecure default in production -- anyone who
knows the default can forge guest tokens accepted by either.
Review Comment:
Right, updated the warning. It's not just a forgery risk, the MCP server
refuses to start with `MCPAuthConfigError` if guest auth is enabled and the
secret's still the default.
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