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Workflow (steps and routing) — Canonical v10

In Canonical v10, workflow: is a list of steps connected by server-side routing (step.next router + next.arcs[]).

A step is composed from:

  • Admission (server): step.spec.policy.admit.rules
  • Execution (worker): step.tool (ordered pipeline of labeled tasks)
  • Routing (server): step.next.spec + step.next.arcs[] guarded by when

Canonical removals (vs legacy docs):

  • no step type: variants (http/python/iterator/…)
  • no step.when
  • no eval/expr/case conditionals (use when only)
  • no step-level retry: wrappers (retry belongs to task.spec.policy.rules)
  • no special “sink” kind (storage is “just tools” returning references)

Minimal example​

workflow:
  - step: start
    next:
      spec: { mode: exclusive }
      arcs:
        - step: fetch

  - step: fetch
    tool:
      - call:
          kind: http
          method: GET
          url: "{{ workload.api_url }}/health"
          spec:
            policy:
              rules:
                - when: "{{ outcome.status == 'error' }}"
                  then: { do: fail }
                - else:
                    then: { do: break }
    next:
      spec: { mode: exclusive }
      arcs:
        - step: end
          when: "{{ event.name == 'step.done' }}"

  - step: end
    tool:
      - done: { kind: noop }

References​

  • documentation/docs/reference/dsl/playbook_structure.md
  • documentation/docs/reference/dsl/step_spec.md