Example 8: A dynamic workflow with static output

Container-based tasks do not output any values to the workflow scheduler, but one way to propagate information through the workflow via container-based tasks is to use static_output property:

An example based on the previous one, but with a 3rd task that gets information from task 2:

Workflow definition

{  "workflow_id": "wf_static_output",  "config": {},  "tasks": [    {      "id": "1",      "execution_configurations": [        {          "function_def_id": "prepFunc",          "priority": 1        }      ],      "successors": [        2      ],      "properties": {        "position": "start"      }    },    {      "id": 2,      "execution_configurations": [        {          "container_def_id": "cdef_hello_world",          "priority": 1        }      ],      "successors": [        3      ],      "properties": {        "scatter": "predecessor_outputs['1']['env_vars']",        "command": [          "sh",          "-c",          "printenv IND"        ],        "environment": "predecessor_outputs['1']['env_vars']",        "static_output": "predecessor_outputs['1']['env_vars']"      }    },    {      "id": 3,      "execution_configurations": [        {          "container_def_id": "cdef_hello_world",          "priority": 1        }      ],      "successors": [        4      ],      "properties": {        "follow": 2,        "command": [          "sh",          "-c",          "printenv IND"        ],        "environment": "predecessor_outputs['2']['static_output']",        "static_output": "predecessor_outputs['2']['static_output']"      }    },    {      "id": 4,      "execution_configurations": [        {          "container_def_id": "cdef_hello_world",          "priority": 1        }      ],      "successors": [],      "properties": {        "follow": 2,        "command": [          "sh",          "-c",          "printenv IND"        ],        "environment": "predecessor_outputs['3']['static_output']"      }    }  ]}

DAG representation

The DAG of the completed workflow with the evaluated "environment" values annotated:

Tasks 2_A, 2_B, 2_C were run in separate containers with different values for environment variable IND.