With distributed training, getting rsync error message and message about head node failure.

```
autogluon.cloud 0.3.1
autogluon.common 1.0.0
autogluon.core 1.0.0
autogluon.features 1.0.0
autogluon.tabular 1.0.0
```
**When making this call, the head node EC2 server is established:**
```
cloud_predictor = TabularCloudPredictor(
cloud_output_path="##masked s3 location##",
backend="ray_aws").fit(
predictor_init_args=PREDICTOR_INIT_ARGS,
predictor_fit_args=PREDICTOR_FIT_ARGS,
instance_type="ml.m5.4xlarge",
framework_version="0.8.2",
wait=True
)
```

**After the head node is setup, the API call produces this output ending with a complaint about rsync file missing.**

```
ssh: connect to host 35.88.54.138 port 22: Connection refused
2024-04-04 23:01:32,960 INFO updater.py:312 -- SSH still not available (SSH command failed.), retrying in 5 seconds.
2024-04-04 23:01:37,965 VINFO command_runner.py:371 -- Running `uptime`
2024-04-04 23:01:37,965 VVINFO command_runner.py:373 -- Full command is `ssh -tt -i /root/ag_automm_tutorial/AutogluonCloudPredictor/ag-20240404_230000/utils/ag_ray_cluster_20240404230041.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ExitOnForwardFailure=yes -o ServerAliveInterval=5 -o ServerAliveCountMax=3 -o ControlMaster=auto -o ControlPath=/tmp/ray_ssh_63a9f0ea7b/58c9a9d082/%C -o ControlPersist=10s -o ConnectTimeout=10s ubuntu@35.88.54.138 bash --login -c -i 'source ~/.bashrc; export OMP_NUM_THREADS=1 PYTHONWARNINGS=ignore && (uptime)'`
ssh: connect to host 35.88.54.138 port 22: Connection refused
2024-04-04 23:01:45,050 INFO updater.py:312 -- SSH still not available (SSH command failed.), retrying in 5 seconds.
2024-04-04 23:01:50,053 VINFO command_runner.py:371 -- Running `uptime`
2024-04-04 23:01:50,054 VVINFO command_runner.py:373 -- Full command is `ssh -tt -i /root/ag_automm_tutorial/AutogluonCloudPredictor/ag-20240404_230000/utils/ag_ray_cluster_20240404230041.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ExitOnForwardFailure=yes -o ServerAliveInterval=5 -o ServerAliveCountMax=3 -o ControlMaster=auto -o ControlPath=/tmp/ray_ssh_63a9f0ea7b/58c9a9d082/%C -o ControlPersist=10s -o ConnectTimeout=10s ubuntu@35.88.54.138 bash --login -c -i 'source ~/.bashrc; export OMP_NUM_THREADS=1 PYTHONWARNINGS=ignore && (uptime)'`
Warning: Permanently added '35.88.54.138' (ECDSA) to the list of known hosts.
23:02:12 up 1 min, 1 user, load average: 2.49, 0.73, 0.25
2024-04-04 23:01:50,063 INFO updater.py:312 -- SSH still not available (SSH command failed.), retrying in 5 seconds.
2024-04-04 23:01:55,065 VINFO command_runner.py:371 -- Running `uptime`
2024-04-04 23:01:55,065 VVINFO command_runner.py:373 -- Full command is `ssh -tt -i /root/ag_automm_tutorial/AutogluonCloudPredictor/ag-20240404_230000/utils/ag_ray_cluster_20240404230041.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ExitOnForwardFailure=yes -o ServerAliveInterval=5 -o ServerAliveCountMax=3 -o ControlMaster=auto -o ControlPath=/tmp/ray_ssh_63a9f0ea7b/58c9a9d082/%C -o ControlPersist=10s -o ConnectTimeout=10s ubuntu@35.88.54.138 bash --login -c -i 'source ~/.bashrc; export OMP_NUM_THREADS=1 PYTHONWARNINGS=ignore && (uptime)'`
Shared connection to 35.88.54.138 closed.
Shared connection to 35.88.54.138 closed.
2024-04-04 23:02:12,246 SUCC updater.py:280 -- Success.
2024-04-04 23:02:12,246 VINFO utils.py:149 -- Creating AWS resource `ssm` in `us-west-2`
2024-04-04 23:02:12,311 VINFO utils.py:170 -- Creating AWS client `ssm` in `us-west-2`
2024-04-04 23:02:12,376 VINFO utils.py:149 -- Creating AWS resource `cloudwatch` in `us-west-2`
2024-04-04 23:02:12,395 INFO updater.py:374 -- Updating cluster configuration. [hash=b52e8ba390e57716b72703a854d9d8bcb065e5e9]
2024-04-04 23:02:13,624 INFO updater.py:381 -- New status: syncing-files
2024-04-04 23:02:13,624 INFO updater.py:238 -- [2/7] Processing file mounts
2024-04-04 23:02:13,624 VINFO command_runner.py:371 -- Running `mkdir -p /tmp/ray_tmp_mount/ag_ray_aws_default_20240404230042/~ && chown -R ubuntu /tmp/ray_tmp_mount/ag_ray_aws_default_20240404230042/~`
2024-04-04 23:02:13,624 VVINFO command_runner.py:373 -- Full command is `ssh -tt -i /root/ag_automm_tutorial/AutogluonCloudPredictor/ag-20240404_230000/utils/ag_ray_cluster_20240404230041.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ExitOnForwardFailure=yes -o ServerAliveInterval=5 -o ServerAliveCountMax=3 -o ControlMaster=auto -o ControlPath=/tmp/ray_ssh_63a9f0ea7b/58c9a9d082/%C -o ControlPersist=10s -o ConnectTimeout=120s ubuntu@35.88.54.138 bash --login -c -i 'source ~/.bashrc; export OMP_NUM_THREADS=1 PYTHONWARNINGS=ignore && (mkdir -p /tmp/ray_tmp_mount/ag_ray_aws_default_20240404230042/~ && chown -R ubuntu /tmp/ray_tmp_mount/ag_ray_aws_default_20240404230042/~)'`
2024-04-04 23:02:14,021 VINFO command_runner.py:414 -- Running `rsync --rsh ssh -i /root/ag_automm_tutorial/AutogluonCloudPredictor/ag-20240404_230000/utils/ag_ray_cluster_20240404230041.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o ExitOnForwardFailure=yes -o ServerAliveInterval=5 -o ServerAliveCountMax=3 -o ControlMaster=auto -o ControlPath=/tmp/ray_ssh_63a9f0ea7b/58c9a9d082/%C -o ControlPersist=10s -o ConnectTimeout=120s -avz /tmp/ray-bootstrap-aim4bkkn ubuntu@35.88.54.138:/tmp/ray_tmp_mount/ag_ray_aws_default_20240404230042/~/ray_bootstrap_config.yaml`
Exception in thread Thread-1:
Traceback (most recent call last):
File "/opt/conda/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
self.run()
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/updater.py", line 153, in run
self.do_update()
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/updater.py", line 382, in do_update
self.sync_file_mounts(self.rsync_up, step_numbers=(1, NUM_SETUP_STEPS))
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/updater.py", line 242, in sync_file_mounts
do_sync(remote_path, local_path)
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/updater.py", line 229, in do_sync
sync_cmd(local_path, remote_path, docker_mount_if_possible=True)
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/updater.py", line 535, in rsync_up
self.cmd_runner.run_rsync_up(source, target, options=options)
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/command_runner.py", line 516, in run_rsync_up
self.ssh_command_runner.run_rsync_up(source, host_destination, options=options)
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/command_runner.py", line 415, in run_rsync_up
self._run_helper(command, silent=is_rsync_silent())
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/command_runner.py", line 272, in _run_helper
return run_cmd_redirected(
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/subprocess_output_util.py", line 341, in run_cmd_redirected
return _run_and_process_output(
File "/opt/conda/lib/python3.10/site-packages/ray/autoscaler/_private/subprocess_output_util.py", line 243, in _run_and_process_output
return process_runner.check_call(
File "/opt/conda/lib/python3.10/subprocess.py", line 364, in check_call
retcode = call(*popenargs, **kwargs)
File "/opt/conda/lib/python3.10/subprocess.py", line 345, in call
with Popen(*popenargs, **kwargs) as p:
File "/opt/conda/lib/python3.10/subprocess.py", line 969, in __init__
self._execute_child(args, executable, preexec_fn, close_fds,
File "/opt/conda/lib/python3.10/subprocess.py", line 1845, in _execute_child
raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'rsync'
2024-04-04 23:02:15,340 PANIC commands.py:851 -- Failed to setup head node.
Error: Failed to setup head node.
2024-04-04 23:02:15,237 ERR updater.py:158 -- New status: update-failed
2024-04-04 23:02:15,237 ERR updater.py:160 -- !!!
2024-04-04 23:02:15,237 VERR updater.py:168 -- {}
2024-04-04 23:02:15,237 ERR updater.py:170 -- [Errno 2] No such file or directory: 'rsync'
2024-04-04 23:02:15,237 ERR updater.py:172 -- !!!
```

Start at the TabularCloudPredictor call using the ray_aws backend and trace the head-node setup through the Ray autoscaler updater and command runner paths shown in the traceback. Reproduce the distributed-training setup and determine why the rsync executable is unavailable; done means setup completes without the missing-rsync failure.

Written by the indexing model from the issue text.