Defaults for Engines and Nested Tasks

In some cases, defining defaults for parameters in the configuration or in the constructor is not sufficient. For example:

• Setting a different default for a config parameter (e.g. main_jar in [spark])
• Setting a different default for all child tasks

task_config

Represents a dictionary of arbitrary configuration params that will be applied to "current" configuration during task creation and run

my_task(task_config={SparkConfig.num_of_executors:3})

$ dbnd run my_task --my_task.task_config="{'spark':{ 'num_of_executors' : 3}}"

To set a default value for a task

Use the defaults attribute as shown in the following examples:

class WordCountTask2(WordCountTask):
    defaults = {
        SparkConfig.main_jar: "jar2.jar",
        DataTask.task_env: DataTaskEnv.prod,
        WordCountTask.text: "/etc/hosts",
    }

class AllWordCounts2(AllWordCounts):
    defaults = {
        SparkConfig.main_jar: "jar2.jar",
        DataTask.task_env: DataTaskEnv.prod,
        WordCountTask.text: "/etc/hosts",
    }

In the example above, we have set the default values for WordCountTask and WordCountPySparkTask tasks.