The Argo Workflow spec: CAPA practice questions

The spec of a Workflow is mostly a list of templates and the name of the entrypoint, the template that runs first. Around that core sit fields that shape the whole run, and reading a manifest quickly depends on knowing which level each field lives at.

spec.arguments holds the global inputs. Parameters declared there are readable in any template as {{workflow.parameters.name}}, and argo submit -p name=value overrides them at submit time without editing the file. Inside a template, inputs.parameters declares what that template expects and {{inputs.parameters.name}} reads it. A step passes values to a template through its own arguments block. Outputs work the same way in reverse: an output parameter takes its value from a file with valueFrom.path, and a script template's standard output appears as outputs.result. Workflow variables also expose run metadata, such as {{workflow.name}} and {{workflow.status}}.

Several spec fields set limits for the whole run. serviceAccountName chooses the service account for all of the workflow's Pods. activeDeadlineSeconds stops the workflow once it has run for that many seconds. parallelism caps how many Pods of this workflow run at once. ttlStrategy deletes the finished Workflow object after a delay that can depend on success or failure, and podGC deletes completed Pods, for example as soon as each one completes. volumeClaimTemplates asks the controller to create persistent volume claims when the run starts and delete them when it ends, which lets steps share a scratch volume.

onExit names an exit handler, a template that runs at the end of the workflow whatever the result was, and reads {{workflow.status}} to decide between cleanup and a failure notice. Lifecycle hooks extend the idea to individual steps or the whole workflow when a condition such as a phase change is met. Many fields also exist on a single template with a narrower scope: retryStrategy, activeDeadlineSeconds, parallelism and the template's own metadata. When a question shows a field, the first thing to settle is whether it sits under spec, which governs the whole run, or under one template, which governs only that task.