title: mlflow tracking server does not start after specifying backend-store-uri
body: <p>I run mlflow as following:</p>
  
  <p><code>Dockerfile</code> contains the the following CMD command</p>
  
  <pre><code>CMD mlflow server \
      --host 0.0.0.0 \
      --backend-store-uri "${BACKEND_STORE_URI}" \
      --default-artifact-root "${DEFAULT_ARTIFACT_ROOT}"
  </code></pre>
  
  <p>after <code>docker run --rm --name mlflow -p 5000:5000 -e BACKEND_STORE_URI=mssql+pymssql://user:pass@mybackendstoreuri/mlflow mlflow</code></p>
  
  <p>it shows </p>
  
  <pre><code>INFO  [alembic.runtime.migration] Context impl MSSQLImpl.
  INFO  [alembic.runtime.migration] Will assume transactional DDL.
  INFO  [alembic.runtime.migration] Context impl MSSQLImpl.
  INFO  [alembic.runtime.migration] Will assume transactional DDL.
  </code></pre>
  
  <p>but then, the container exits without starting the server. </p>
  
  <p>Without specifying <code>backend store uri</code>, I can see the logs related to binding to host, and the container does not exist</p>
  
  <p>How to run mlflow tracking server and use backend store uri ?</p>