SDK command name %q is ambiguous: modules.%s.as-sdk and modu

Error message

SDK command name %q is ambiguous: modules.%s.as-sdk and modules.%s.as-sdk both use it

What it means

Thrown by configuredSDKs when registering dynamic `dagger sdk init <name>` commands from a workspace config: two different modules declare `as-sdk` entries that resolve to the same CLI command name. Because the command name must be unique, registration is rejected with both conflicting module names listed.

Source

Thrown at internal/cmd/dagger/sdk_init_dynamic.go:144

	if entry.AsSDK != nil && entry.AsSDK.Name != "" {
		return entry.AsSDK.Name
	}
	return moduleName
}

func configuredSDKs(cfg *workspace.Config) ([]configuredSDK, error) {
	if cfg == nil || cfg.Modules == nil {
		return nil, nil
	}
	sdks := make([]configuredSDK, 0, len(cfg.Modules))
	seen := map[string]string{}
	for moduleName, entry := range cfg.Modules {
		if entry.AsSDK == nil {
			continue
		}
		commandName := sdkCommandName(moduleName, entry)
		if existing, ok := seen[commandName]; ok {
			return nil, fmt.Errorf("SDK command name %q is ambiguous: modules.%s.as-sdk and modules.%s.as-sdk both use it", commandName, existing, moduleName)
		}
		seen[commandName] = moduleName
		sdks = append(sdks, configuredSDK{
			moduleName:  moduleName,
			commandName: commandName,
			entry:       entry,
		})
	}
	sort.Slice(sdks, func(i, j int) bool {
		if sdks[i].commandName != sdks[j].commandName {
			return sdks[i].commandName < sdks[j].commandName
		}
		return sdks[i].moduleName < sdks[j].moduleName
	})
	return sdks, nil
}

func resolveConfiguredSDK(cfg *workspace.Config, sdkName string) (configuredSDK, error) {

View on GitHub (pinned to 82ba2681db)

Solutions

Rename one entry's `as-sdk.name` in dagger.json so each SDK command name is unique
Remove the duplicate as-sdk entry if one module is no longer meant to be an SDK
Run `dagger sdk list` after fixing to confirm commands register cleanly

Example fix

// before (dagger.json)
"modules": { "a": {"as-sdk": {"name": "py"}}, "b": {"as-sdk": {"name": "py"}} }
// after
"modules": { "a": {"as-sdk": {"name": "py"}}, "b": {"as-sdk": {"name": "py2"}} }

Defensive patterns

Strategy: validation

Validate before calling

names=$(jq -r '.modules | to_entries[] | select(.value."as-sdk") | .value."as-sdk".name // .key' dagger.json); d=$(echo "$names" | sort | uniq -d); [ -z "$d" ] || echo "duplicate SDK command names: $d"

Try / catch

if err := cfg.Validate(); err != nil && strings.Contains(err.Error(), "is ambiguous") { return fmt.Errorf("fix dagger.json: %w", err) }

Prevention

Give every as-sdk entry a unique explicit name in dagger.json
Run `dagger sdk list` after editing modules to catch duplicates early
When copying module entries, always update the as-sdk name

When it happens

Trigger: Workspace config has two modules, e.g. modules.A.as-sdk and modules.B.as-sdk, whose effective command names (explicit as-sdk.name or module name) are identical.

Common situations: Copying a module entry in dagger.json and forgetting to change its as-sdk name; two modules deliberately named the same; an explicit `as-sdk: name` duplicating another module's default command name.

Related errors

AI-assisted analysis of dagger/dagger@82ba2681db (2026-09-05). Data as JSON: /api/errors/be7595884606ab5e. Report an issue: GitHub.