title: Ray cluster ModuleNotFoundError
body: <p>I am new to Ray and wanted to set up a cluster with some dependencies. I first set up a cluster with some dependencies supported out of the box and everything worked fine. Now, I have the following scenario that I simplified to this demonstration. There is a problem with <code>joblib</code> even though I specify it in a runtime env as to be downloaded with pip and then pass it to <code>ray.init</code>.</p>
  <pre><code>from ray.util.joblib import register_ray
  import joblib
  import ray
  import numpy as np
  
  # connect to ray
  runtime_env={&quot;pip&quot;: [&quot;joblib&quot;]}
  ray.init(address='auto', _redis_password=..., runtime_env=runtime_env)
  
  
  @ray.remote(num_cpus=1)
  def train_ray(...):
      ...
      register_ray()
      with joblib.parallel_backend('ray'):
          ...
    
      return ...
  </code></pre>
  <p>I get the following error:</p>
  <pre><code>    from ray.util.joblib import register_ray
    File &quot;/home/ray/anaconda3/lib/python3.7/site-packages/ray/util/joblib/__init__.py&quot;, line 1, in &lt;module&gt;
      from joblib.parallel import register_parallel_backend
  ModuleNotFoundError: No module named 'joblib'
  command terminated with exit code 1
  </code></pre>
  <p>Thanks for any suggestions.</p>