stamparm/maltrail · error

write worker config

Error message

write worker config

What it means

Panic from `.expect("write worker config")` when `std::fs::write` fails to write the generated `worker.conf` containing MONITOR_INTERFACE, LOG_DIR and TRAILS_FILE lines. The worker context cannot proceed without its config file.

Solutions

  1. Check temp dir writability and free space
  2. Remove any non-file entry at the worker.conf path
  3. Set TMPDIR to a known-writable directory for test runs
  4. Match on the fs::write result to log the underlying io::Error
Defensive patterns

Strategy: try-catch

Validate before calling

assert!(dir.is_dir(), "temp dir must exist before writing worker.conf");

Try / catch

std::fs::write(&config_file, body).unwrap_or_else(|e| panic!("write worker config {}: {e}", config_file.display()));

Prevention

When it happens

Trigger: `worker_context()` invoked while the temp filesystem is full, read-only, or the path worker.conf is occupied by a directory; permissions changed after dir creation.

Common situations: Containerized CI with small tmpfs; sandboxed environments blocking writes; leftover directory named worker.conf from a corrupted earlier run.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

AI-assisted analysis of stamparm/maltrail@77cfb06d76 (2026-09-13). Data as JSON: /api/errors/690d0c291062ab7a. Report an issue: GitHub.

Appendix: source

Thrown at sensor/src/testkit.rs:323

    let config_file = dir.join("worker.conf");
    std::fs::write(
        &config_file,
        format!(
            "MONITOR_INTERFACE any\n\
             CAPTURE_BUFFER 1MB\n\
             PROCESS_COUNT 1\n\
             UPDATE_PERIOD 999999999\n\
             DISABLE_CHECK_SUDO true\n\
             USE_CONDENSED_STORAGE false\n\
             USE_HEURISTICS false\n\
             SENSOR_NAME harness\n\
             LOG_DIR {}\n\
             TRAILS_FILE {}\n",
            log_dir.display(),
            trails_file.display()
        ),
    )
    .expect("write worker config");

    let root = repo_root();
    let mut cfg = Config::load(&config_file).expect("worker config must load");
    cfg.root = root.clone();
    settings::init(root);
    crate::output::init_error_log(&log_dir, false);

    crate::worker::WorkerContext {
        id,
        cfg: Arc::new(cfg),
        whitelist: Arc::new(Whitelist::default()),
        store: Arc::new(TrailStore::new(build_db(&[]))),
        output: Arc::new(OutputConfig {
            sensor_name: "harness".to_string(),
            log_dir,
            trails_file,
            disable_local_log_storage: false,
            local_log_json: false,

View on GitHub (pinned to 77cfb06d76)