apache/druid · error · IllegalStateException

Failed to parse metric dimensions and types

Error message

Failed to parse metric dimensions and types

What it means

Sentinel-style failure in DropwizardConverter.readMap(): the dimension/type mapping file referenced by dimensionMapPath could not be opened or deserialized into Map<String, DropwizardMetricSpec> (bad path, unreadable file, or invalid JSON structure). The converter cannot map incoming metric names to dropwizard names/types/dimensions without this file, so it aborts with this message and the underlying cause attached.

Solutions

1. Check dimensionMapPath points to an existing, readable file with valid JSON matching Map<String, DropwizardMetricSpec>.
2. Validate the mapping file's syntax and required fields (dimensions, type).

When it happens

Trigger: Thrown at extensions-contrib/dropwizard-emitter/src/main/java/org/apache/druid/emitter/dropwizard/DropwizardConverter.java:88 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/11e053a7ba54a17d. Report an issue: GitHub.

Appendix: source

Thrown at extensions-contrib/dropwizard-emitter/src/main/java/org/apache/druid/emitter/dropwizard/DropwizardConverter.java:88

      for (String dim : metricSpec.getDimensions()) {
        if (userDims.containsKey(dim)) {
          filteredDimensions.put(dim, userDims.get(dim).toString());
        }
      }
      return metricSpec;
    } else {
      // No mapping found for given metric, return null
      return null;
    }
  }

  private Map<String, DropwizardMetricSpec> readMap(ObjectMapper mapper, String dimensionMapPath)
  {
    try (final InputStream is = openDimensionMapFile(dimensionMapPath)) {
      return mapper.readerFor(new TypeReference<Map<String, DropwizardMetricSpec>>() {}).readValue(is);
    }
    catch (IOException e) {
      throw new ISE(e, "Failed to parse metric dimensions and types");
    }
  }

  private InputStream openDimensionMapFile(@Nullable String dimensionMapPath) throws IOException
  {
    if (Strings.isNullOrEmpty(dimensionMapPath)) {
      log.info("Using default metric dimension and types");
      return this.getClass().getClassLoader().getResourceAsStream("defaultMetricDimensions.json");
    } else {
      log.info("Using metric dimensions at types at [%s]", dimensionMapPath);
      return new FileInputStream(dimensionMapPath);
    }
  }
}

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