Add fallback for pure python worker

config/dev.ini

@@ -6,7 +6,7 @@ GALAXY_CONFIG_FILE=config/galaxy.yml
 PYTHONPATH=lib
 
 [watcher:web]
-cmd = gunicorn 'galaxy.webapps.galaxy.fast_factory:factory()' --timeout 300 --pythonpath lib -k uvicorn.workers.UvicornWorker -b fd://$(circus.sockets.web)
+cmd = gunicorn 'galaxy.webapps.galaxy.fast_factory:factory()' --timeout 300 --pythonpath lib -k galaxy.webapps.galaxy.workers.Worker -b fd://$(circus.sockets.web)
 send_hup = true
 numprocesses = 1
 use_sockets = True

lib/galaxy/webapps/galaxy/workers.py

@@ -0,0 +1,9 @@
+import logging
+log = logging.getLogger(__name__)
+
+try:
+    import uvloop  # noqa: F401
+    from uvicorn.workers import UvicornWorker as Worker
+except ImportError:
+    log.warning("uvtools not available, falling back to pure python worker")
+    from uvicorn.workers import UvicornH11Worker as Worker  # noqa: F401