compactor service enabled but no compaction client available

Error message

compactor service enabled but no compaction client available

What it means

When the node is configured as a compactor (compactor service enabled), serve_quickwit expects an optional compaction service client to have been created earlier. The expect enforces the invariant that an enabled compactor always has a client; None means the configuration-to-client wiring failed upstream.

Source

Thrown at quickwit/quickwit-serve/src/lib.rs:860

        )
        .await
        .context("failed to start janitor service")?;
        Some(janitor_service)
    } else {
        None
    };

    let compactor_supervisor_opt = if node_config.is_service_enabled(QuickwitService::Compactor)
        && node_config.enable_standalone_compactors
    {
        let compaction_dir = node_config.data_dir_path.join("compaction");
        fs::create_dir_all(&compaction_dir)?;
        let compaction_root_directory = quickwit_common::temp_dir::Builder::default()
            .tempdir_in(&compaction_dir)
            .context("failed to create compaction temp directory")?;
        let compaction_client = compaction_service_client_opt
            .clone()
            .expect("compactor service enabled but no compaction client available");
        let split_cache = indexing_split_cache.clone();
        let compactor_mailbox = start_compactor_service(
            &universe,
            cluster.self_node_id(),
            compaction_client,
            &node_config.compactor_config,
            primary_metastore_client.clone(),
            storage_resolver.clone(),
            split_cache,
            event_broker.clone(),
            compaction_root_directory,
        )
        .await
        .context("failed to start compactor service")?;
        Some(compactor_mailbox)
    } else {
        None
    };

View on GitHub (pinned to a39730c5cd)

Solutions

Review the compactor section of quickwit.yaml: it must be complete and consistent when compaction is enabled
Trace where compaction_service_client_opt is set and confirm it covers the enabled case
Validate the config with quickwit's config checker before startup
If wiring is broken after a code change, restore client construction for the enabled path

Defensive patterns

Strategy: validation

Validate before calling

// Validate config before starting the node:
if node_config.compactor_config.enabled && compaction_service_client_opt.is_none() {
    return Err(anyhow!("compactor enabled but compaction client missing"));
}

Prevention

Run the quickwit config checker on quickwit.yaml before deployment
Keep the compactor client construction adjacent to the enabled check
Add an integration test that enables compaction and asserts the client exists

When it happens

Trigger: node_config.compactor_config enables the compactor but the code path that builds compaction_service_client_opt did not run or returned None (e.g. missing/garbled configuration section or a bug in client construction).

Common situations: Config file with compactor.enabled: true but malformed/absent compaction client settings; refactoring that reordered client initialization before the flag check.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

AI-assisted analysis of quickwit-oss/quickwit@a39730c5cd (2026-09-08). Data as JSON: /api/errors/5469b6519ac209ce. Report an issue: GitHub.