diff --git a/src/dstack/_internal/server/services/users.py b/src/dstack/_internal/server/services/users.py
index 73ceebe0e..35c1fe5b3 100644
--- a/src/dstack/_internal/server/services/users.py
+++ b/src/dstack/_internal/server/services/users.py
@@ -32,6 +32,7 @@
 from dstack._internal.server.services import events
 from dstack._internal.server.services.locking import get_locker
 from dstack._internal.server.services.permissions import get_default_permissions
+from dstack._internal.server.utils import otel
 from dstack._internal.server.utils.routers import error_forbidden
 from dstack._internal.utils import crypto
 from dstack._internal.utils.common import get_current_datetime, get_or_error, run_async
@@ -397,6 +398,7 @@ async def log_in_with_token(session: AsyncSession, token: str) -> Optional[UserM
         return None
     if user.token.get_plaintext_or_error() != token:
         return None
+    otel.set_current_span_attribute("dstack.user.name", user.name)
     return user
 
 
diff --git a/src/dstack/_internal/server/utils/otel/__init__.py b/src/dstack/_internal/server/utils/otel/__init__.py
index 1b63bfd41..ee7f831b7 100644
--- a/src/dstack/_internal/server/utils/otel/__init__.py
+++ b/src/dstack/_internal/server/utils/otel/__init__.py
@@ -3,6 +3,7 @@
 
 if TYPE_CHECKING:
     from fastapi import FastAPI
+    from opentelemetry.util.types import AttributeValue
     from sqlalchemy.ext.asyncio import AsyncEngine
 
 try:
@@ -54,3 +55,13 @@ def record_task_run(name: str, *, error: bool) -> None:
     if _task_runs_counter is None:
         return
     _task_runs_counter.add(1, {"task": name, "status": "error" if error else "success"})
+
+
+def set_current_span_attribute(key: str, value: "AttributeValue") -> None:
+    """
+    Sets an attribute on the currently active span.
+    No-op if OpenTelemetry is not installed or tracing is not configured.
+    """
+    if otel_trace is None:
+        return
+    otel_trace.get_current_span().set_attribute(key, value)