What causes "found duplicate custom action %s. Custom action names must be unique" in GoogleContainerTools/skaffold?

Rename one of the duplicate custom actions to a unique name

found duplicate custom action %s. Custom action names must b

Error message

found duplicate custom action %s. Custom action names must be unique

What it means

Custom action names must be unique across all pipelines in the run context because Skaffold references actions by name (e.g. in execution modes and pipelines). validateCustomActionsNames collects customActions from every pipeline and errors when a name repeats.

Source

Thrown at pkg/skaffold/schema/validation/validation.go:745

	}
	return errs
}

// validateCustomActions
// - makes sure that each custom action name is unique
// - makes sure that each custom action container name is unique
func validateCustomActionsNames(runCtx *runcontext.RunContext) (errs []error) {
	acs := []latest.Action{}
	seenAcs := map[string]bool{}
	seenConts := map[string]bool{}

	for _, pipeline := range runCtx.GetPipelines() {
		acs = append(acs, pipeline.CustomActions...)
	}

	for _, a := range acs {
		if _, found := seenAcs[a.Name]; found {
			errs = append(errs, fmt.Errorf("found duplicate custom action %s. Custom action names must be unique", a.Name))
		}

		for _, c := range a.Containers {
			if _, found := seenConts[c.Name]; found {
				errs = append(errs, fmt.Errorf("found duplicate container name %s in custom action. Container names must be unique", c.Name))
			}
			seenConts[c.Name] = true
		}

		seenAcs[a.Name] = true
	}

	return
}

// validateCustomActionsLists
// - makes sure that each custom action has one or more containers
func validateCustomActionsLists(runCtx *runcontext.RunContext) (errs []error) {

View on GitHub (pinned to a1189de023)

Solutions

Rename one of the duplicate custom actions to a unique name
Remove the accidental duplicate action
Prefix action names per module when combining multiple skaffold configs

Example fix

# before
customActions:
  - name: migrate
    containers: [{ name: db, image: migrate:1 }]
  - name: migrate
    containers: [{ name: db2, image: migrate:2 }]
# after
customActions:
  - name: migrate-v1
    containers: [{ name: db, image: migrate:1 }]
  - name: migrate-v2
    containers: [{ name: db2, image: migrate:2 }]

Defensive patterns

Strategy: validation

Validate before calling

const names = configs.flatMap(c => (c.customActions ?? []).map(a => a.name));
const dupes = names.filter((n, i) => names.indexOf(n) !== i);
if (dupes.length) throw new Error(`duplicate custom actions: ${[...new Set(dupes)].join(', ')}`);

Try / catch

try {
  await skaffold.run(config);
} catch (e) {
  if (/found duplicate custom action/.test(e.message)) {
    console.error('Rename or remove the duplicated custom action');
  } else throw e;
}

Prevention

Prefix custom action names per module/config (e.g. payments-migrate)
Search all composed skaffold configs for the action name before adding it
Keep a naming convention doc for custom actions in multi-module repos

When it happens

Trigger: Two customActions entries with the same `name:` across the pipelines of a run context, processed via ProcessWithRunContext.

Common situations: Copy-pasting a custom action without renaming it, or multi-config projects where each module defines an action with the same generic name like 'migrate-db'.

Related errors

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/34ba49c26753419a. Report an issue: GitHub.