What causes "Log file content is empty, get log path : %s" in apache/seatunnel?

Wait until the node has written output and retry the log request

Log file content is empty, get log path : %s

Error message

Log file content is empty, get log path : %s

What it means

Logged when the servlet attempts to read a log file and a SeaTunnelRuntimeException with empty content is thrown, meaning the resolved log file exists at the path but has no readable content. The servlet responds with HTTP 400.

Source

Thrown at seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/rest/servlet/LogBaseServlet.java:78

            String canonicalFilePath = new File(logFilePath).getCanonicalPath();
            if (!canonicalFilePath.startsWith(canonicalLogDir + File.separator)
                    && !canonicalFilePath.equals(canonicalLogDir)) {
                resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
                log.warn(
                        "Path traversal attempt blocked - Requested: {}, Resolved: {}, LogDir: {}",
                        logName,
                        canonicalFilePath,
                        canonicalLogDir);
                return;
            }
            String logContent = FileUtils.readFileToStr(new File(canonicalFilePath).toPath());
            write(resp, logContent);
        } catch (IOException e) {
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            log.warn("Failed to resolve log file path: {}, error: {}", logFilePath, e.getMessage());
        } catch (SeaTunnelRuntimeException e) {
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            log.warn(String.format("Log file content is empty, get log path : %s", logFilePath));
        }
    }
}

View on GitHub (pinned to cf67b549a7)

Solutions

Wait until the node has written output and retry the log request
Verify the correct node name — request logs from the specific worker that ran the job
Check the log file on disk directly (ls -la on the log dir) to confirm whether it is 0 bytes
Inspect the actual cause in server logs; this message hides the underlying error detail

Defensive patterns

Strategy: retry

Validate before calling

// give a freshly started node time to write logs before requesting
await new Promise(r => setTimeout(r, 5000));

Try / catch

try {
  const resp = await fetch(baseUrl + '/log/' + node);
  if (resp.status === 400) {
    const body = await resp.text();
    if (body.includes('empty')) { /* retry later or read file on disk */ }
  }
} catch (e) { /* handle network errors */ }

Prevention

Don't request logs immediately after node startup; add a small delay
Verify the node actually produced output before fetching its log
Check log rotation settings to avoid zero-byte truncated files
When persistent, read the file directly on the host to compare with the REST result

When it happens

Trigger: Requesting a log endpoint for a log file that is empty (0 bytes) — e.g. a worker log created but nothing written yet, or a read returning empty content wrapped in SeaTunnelRuntimeException.

Common situations: Requesting a freshly started node's log before any output; a log rotated/truncated to zero; requesting a log file that was created on a node whose log path differs from the master's.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/2f692db09062071d. Report an issue: GitHub.