[Bug]: Salt fileserver update does not work with S3 buckets

What happened?

Error:
Exception occurred in runner fileserver.update: Traceback (most recent call last): File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/client/mixins.py", line 383, in low data["return"] = func(*args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 163, in __call__ ret = self.loader.run(run_func, *args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1275, in run return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1290, in _run_as ret = _func_or_method(*args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/runners/fileserver.py", line 353, in update fileserver.update(back=backend, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/fileserver/__init__.py", line 474, in update self.servers[fstr](**kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 163, in __call__ ret = self.loader.run(run_func, *args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1275, in run return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1290, in _run_as ret = _func_or_method(*args, **kwargs) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/fileserver/s3fs.py", line 125, in update metadata = _init() File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/fileserver/s3fs.py", line 371, in _init _prune_deleted_files(metadata) File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/fileserver/s3fs.py", line 594, in _prune_deleted_files cached_files.add(meta["Key"]) KeyError: 'Key'

https://github.com/saltstack/salt/blob/v3007.7/salt/fileserver/s3fs.py#L593-L594

for meta in env_data: cached_files.add(meta["Key"])

Please change this to:

for meta in env_data: for bucket in meta.keys(): for obj in meta[bucket]: cached_files.add(obj["Key"])
This has been broken for many versions now and we'd like to use a working salt installation out of the box.

Type of salt install

Official deb

Major version

3007.x

What supported OS are you seeing the problem on? Can select multiple. (If bug appears on an unsupported OS, please open a GitHub Discussion instead)

ubuntu-24.04

salt --versions-report output

Salt Version:
          Salt: 3007.7

Python Version:
        Python: 3.10.18 (main, Aug 27 2025, 20:27:59) [GCC 11.2.0]

Dependency Versions:
          cffi: 1.16.0
      cherrypy: unknown
  cryptography: 42.0.5
      dateutil: 2.8.2
     docker-py: Not Installed
         gitdb: 4.0.12
     gitpython: 3.1.44
        Jinja2: 3.1.6
       libgit2: Not Installed
  looseversion: 1.3.0
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.7
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     packaging: 24.0
     pycparser: 2.21
      pycrypto: Not Installed
  pycryptodome: 3.19.1
        pygit2: Not Installed
  python-gnupg: 0.5.2
        PyYAML: 6.0.1
         PyZMQ: 25.1.2
        relenv: 0.20.5
         smmap: 5.0.2
       timelib: 0.3.0
       Tornado: 6.4.2
           ZMQ: 4.3.4

Salt Package Information:
  Package Type: onedir

System Versions:
          dist: ubuntu 24.04.1 noble
        locale: utf-8
       machine: aarch64
       release: 6.14.0-1012-aws
        system: Linux
       version: Ubuntu 24.04.1 noble

Start in salt/fileserver/s3fs.py around _prune_deleted_files(), especially the metadata handling at the reported lines. Review the linked pull request before making changes, then verify that fileserver.update handles the S3 metadata structure without raising KeyError.