automatic_task_retry.yml

# This example workflow demonstrates how to automatically retry a task.
#
# Workflows in the Civis Platform are written in YAML and a workflow DSL
# (domain specific language) called Mistral.
#
# See this website, https://docs.ansible.com/ansible/latest/reference_appendices/YAMLSyntax.html,
# for an introduction to YAML.
#
# See the Mistral documentation, https://docs.openstack.org/mistral/train/user/wf_lang_v2.html,
# for a description of the Mistral DSL.

version: '2.0'  # you always need this key to specify version 2 of the mistral DSL
workflow:
  tasks:
    retry_this_job:
      action: civis.scripts.python3
      # This is specified for the task, not the input
      retry:
        # Number of attempts, not including the first one.
        # A count of 1 means there are 2 attempts.
        count: 1
        # Delay between attempts in seconds
        delay: 5
      input:
        # This code looks at the current workflow & execution
        # to find out if it's running for the first time.
        # If it is, it fails. The second time it'll successfully complete.
        source: |
          import os
          import civis

          client = civis.APIClient()
          resp = client.workflows.get_executions(
            <% $.get('__env').workflow_id %>,
            <% $.get('__env').execution_id %>,
          )

          if len(resp.tasks[0].runs) <= 1:
            raise ValueError('This job always fails the first time')

          print('It worked this time!')