apache/druid · error · IllegalArgumentException

Arguments cannot be empty of null

Error message

Arguments cannot be empty of null

What it means

Generic validation helper in GceUtils.buildFilter: the caller passed a null/empty term list or a null/empty key when constructing a GCE API filter string. Without terms or a key no meaningful filter can be built, so the utility rejects the arguments instead of issuing a malformed list request.

Solutions

1. Ensure the instance/term list passed to GceUtils methods is populated before building filters (check autoscaler config for valid host patterns).
2. Validate the filter key (e.g. 'name') is non-empty at the call site.
3. Add logging of the offending list/key to identify which caller passed empty arguments.

When it happens

Trigger: Thrown at extensions-contrib/gce-extensions/src/main/java/org/apache/druid/indexing/overlord/autoscaling/gce/GceUtils.java:57 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/701d9847dc50bc48. Report an issue: GitHub.

Appendix: source

Thrown at extensions-contrib/gce-extensions/src/main/java/org/apache/druid/indexing/overlord/autoscaling/gce/GceUtils.java:57

    String name = instance;
    if (instance != null && !instance.isEmpty()) {
      int lastSlash = instance.lastIndexOf('/');
      if (lastSlash > -1) {
        name = instance.substring(lastSlash + 1);
      } else {
        name = instance; // let's assume not the URI like thing
      }
    }
    return name;
  }

  /**
   * Converts a list of terms to a 'OR' list of terms to look for a specific 'key'
   */
  public static String buildFilter(List<String> list, String key)
  {
    if (list == null || list.isEmpty() || key == null || key.isEmpty()) {
      throw new IllegalArgumentException("Arguments cannot be empty of null");
    }
    Iterator<String> it = list.iterator();

    StringBuilder sb = new StringBuilder();
    sb.append(StringUtils.format("(%s = \"%s\")", key, it.next()));
    while (it.hasNext()) {
      sb.append(" OR ").append(StringUtils.format("(%s = \"%s\")", key, it.next()));
    }
    return sb.toString();
  }

  // cannot build it!
  private GceUtils()
  {
  }
}

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