`doctl registry` commands fail with 412 for multi-registry accounts without clear error or guidance

[silvercondor]

Description

All doctl registry subcommands (repository list-v2, repository list-manifests, repository delete-manifest, etc.) fail with an opaque 412 error when the account has multiple container registries, even though the --registry flag is documented as "optional."

This appears to be a server-side API change — these commands previously worked without --registry. There was no deprecation notice, changelog entry, or doctl release noting this breaking change.

Steps to Reproduce

1. Have a DigitalOcean account with multiple container registries
2. Run any registry command without --registry:

doctl registry repository list-v2 --output json

Expected Behavior

Either:

• A clear CLI-level error message like: Error: multiple registries found. Please specify one with --registry <name>. Available: reg1, reg2
• Or the command prompts the user to select a registry

Actual Behavior

Raw API error passed through:

{
  "errors": [
    {
      "detail": "failed to get registry: GET https://api.digitalocean.com/v2/registry: 412 (request \"...\") This API is not supported if you have created multiple registries. Please use '/v2/registries/{registry_name}' instead. Refer to https://docs.digitalocean.com/reference/api/digitalocean/#tag/Container-Registry for more info."
    }
  ]
}

Suggested Fix

• Detect multi-registry accounts in doctl and surface a user-friendly error with available registry names
• Update the --registry flag description — it's not truly "optional" for multi-registry accounts
• Document this as a breaking change for users who previously had a single registry and later created a second one

Environment

• doctl version: 1.151.0 (also reproduced with 1.141.0 via digitalocean/action-doctl@v2)
• Affected commands: registry get, registry repository list-v2, registry repository list-manifests, registry repository delete-manifest, registry garbage-collection start

Impact

This silently broke CI/CD pipelines (GitHub Actions cron jobs) that were using doctl registry commands without --registry. The workaround is to add --registry <name> to every command (or positional arg for garbage-collection start).

[anup-deka]

Hey,
/v2/registry endpoint is deprecated so doctl registry commands might not work in future
We will be removing the registry subcommand soon, please use doctl registries instead which have extended support for multiple registries

https://docs.digitalocean.com/reference/api/digitalocean/#tag/Container-Registry

[anup-deka]

Fixed by #1817