title: MissingConfigVariableError while creating DataContext in Great Expectations
body: <ol>
  <li>Unable to create DataContext with the following configuration.I am try to use a Databricks spark df datasource and in house DB as storeBackendDefaults</li>
  <li>I get the MissingConfigVariableError exceptions</li>
  <li>Could some explain what I am missing</li>
  </ol>
  <pre><code>import great_expectations as ge
  import great_expectations.exceptions as ge_exceptions
  from great_expectations.data_context.types.base import DataContextConfig, DatasourceConfig, FilesystemStoreBackendDefaults, DatabaseStoreBackendDefaults
  from great_expectations.data_context import BaseDataContext
  
  my_spark_datasource_config = DatasourceConfig(
      class_name=&quot;Datasource&quot;,
      execution_engine={&quot;class_name&quot;: &quot;SparkDFExecutionEngine&quot;},
      data_connectors={&quot;sample_sparkdf_runtime_data_connector&quot;: {
              &quot;module_name&quot;: &quot;great_expectations.datasource.data_connector&quot;,
              &quot;class_name&quot;: &quot;RuntimeDataConnector&quot;,
              &quot;batch_identifiers&quot;: [
                  &quot;some_key_maybe_pipeline_stage&quot;,
                  &quot;some_other_key_maybe_run_id&quot;
              ]
          }
      }
  )
  
  
  data_context_config = DataContextConfig(config_version = 2
                                          ,plugins_directory = None
                                          ,config_variables_file_path = None
                                          ,datasources={&quot;my_spark_datasource&quot;: my_spark_datasource_config}
                                          ,store_backend_defaults=DatabaseStoreBackendDefaults(default_credentials = {
                                                                                                                        &quot;drivername&quot;: &quot;PrestoSQL&quot;,
                                                                                                                        &quot;host&quot;: &quot;*****&quot;,
                                                                                                                        &quot;port&quot;: &quot;443&quot;,
                                                                                                                        &quot;username&quot;: &quot;*****&quot;,
                                                                                                                        &quot;password&quot;: &quot;*****&quot;,
                                                                                                                        &quot;database&quot;: &quot;****&quot;
                                                                                                                      }
                                                                                              ),
      anonymous_usage_statistics={&quot;enabled&quot;: False}
                                        )
  
  context = BaseDataContext(project_config=data_context_config)
  </code></pre>