What causes "[{0}] is not a file" in apache/hadoop?

Check ls -ld on the exact path from the message; if it is a directory, remove it and install the XML file (or point httpfs.config.dir at the right directory).

apache/hadoop · critical · ServerException

S05

S05

Error message

[{0}] is not a file

What it means

While loading site configuration, Server.initConfig() accepts a missing httpfs-site.xml (warn only) but if the path exists yet is not a regular file — typically a directory — it throws ServerException S05('[<path>] is not a file') and aborts startup.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/server/Server.java:469

      defaultConf = new Configuration(false);
    } else {
      try {
        defaultConf = new Configuration(false);
        ConfigurationUtils.load(defaultConf, inputStream);
      } catch (Exception ex) {
        throw new ServerException(ServerException.ERROR.S03, defaultConfig, ex.getMessage(), ex);
      }
    }

    if (config == null) {
      Configuration siteConf;
      File siteFile = new File(file, name + "-site.xml");
      if (!siteFile.exists()) {
        log.warn("Site configuration file [{}] not found in config directory", siteFile);
        siteConf = new Configuration(false);
      } else {
        if (!siteFile.isFile()) {
          throw new ServerException(ServerException.ERROR.S05, siteFile.getAbsolutePath());
        }
        try {
          log.debug("Loading site configuration from [{}]", siteFile);
          inputStream = Files.newInputStream(siteFile.toPath());
          siteConf = new Configuration(false);
          ConfigurationUtils.load(siteConf, inputStream);
        } catch (IOException ex) {
          throw new ServerException(ServerException.ERROR.S06, siteFile, ex.getMessage(), ex);
        }
      }

      config = new Configuration(false);
      ConfigurationUtils.copy(siteConf, config);
    }

    ConfigurationUtils.injectDefaults(defaultConf, config);
    ConfigRedactor redactor = new ConfigRedactor(config);
    for (String name : System.getProperties().stringPropertyNames()) {

View on GitHub (pinned to 2add963021)

Solutions

Check ls -ld on the exact path from the message; if it is a directory, remove it and install the XML file (or point httpfs.config.dir at the right directory).
For configMap-style mounts, mount the key as a subPath/file so the final path is a regular file.
Re-run startup and confirm it reaches init of services.

Example fix

# before
$ ls -ld /etc/hadoop/httpfs/conf/httpfs-site.xml
drwxr-xr-x 2 root root ... /etc/hadoop/httpfs/conf/httpfs-site.xml  # directory!

# after
$ rmdir /etc/hadoop/httpfs/conf/httpfs-site.xml
$ cp httpfs-site.xml /etc/hadoop/httpfs/conf/httpfs-site.xml

Defensive patterns

Strategy: validation

Validate before calling

# pre-start: site file must be a regular file if present
SITE="${HTTPFS_CONFIG}/httpfs-site.xml"
if [ -e "$SITE" ] && [ ! -f "$SITE" ]; then
  echo "FATAL: $SITE exists but is not a regular file"; exit 1
fi

Prevention

Mount configMap keys as files (subPath), not as directories over the file path.
Lint config trees after every config-management run: find path -type d where a file is expected.
Keep the config dir vs config file distinction explicit in scripts.

When it happens

Trigger: /etc/hadoop/conf/httpfs-site.xml created as a directory (e.g. by mkdir -p gone wrong or a mount point placeholder); a bind-mount that mounted a directory over the expected file path; tooling that creates empty directory stubs for config paths.

Common situations: Config-management systems (Puppet/Chef/Ansible) managing the path as a directory resource; Kubernetes configMap volume mounts that expose a directory where a single file was expected; operators confusing the config DIR and the site FILE path.

Related errors

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/26cdff37bff4959c. Report an issue: GitHub.