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VOLODYSLAV_HOSTNAME

Purpose​

VOLODYSLAV_HOSTNAME is an environment variable that identifies the machine on which a Volodyslav instance is running.

Because Volodyslav can be deployed and run on multiple hosts simultaneously, it is important to track where data was created. This variable provides that information at the source — both for event log entries and for nodes in the incremental computation graph.

How It Works​

Event Log Entries​

Every event in the event log carries a creator structure that records metadata about the Volodyslav instance that created it. With VOLODYSLAV_HOSTNAME, this structure now includes a hostname field:

{
  "creator": {
    "name": "Volodyslav",
    "uuid": "81c3188c-d2cc-4879-a237-cdd0f1121346",
    "version": "1.2.3",
    "hostname": "my-server.example.com"
  }
}

The hostname field tells you which machine produced the event entry. This is helpful when you have multiple hosts all writing to the same shared event log repository, and you want to understand the provenance of each entry.

Incremental Graph Nodes​

The incremental computation graph caches computed node values in a database. Each node records createdAt, modifiedAt, and now also createdBy in its stored record. The createdBy field holds the hostname of the machine that first computed the node.

Like createdAt, the createdBy value is immutable after first creation: subsequent recomputations on a different host will not change the recorded hostname. This ensures a stable record of where the computation originally took place.

Configuration​

Set VOLODYSLAV_HOSTNAME to a string that uniquely identifies the host within your deployment. Examples:

# A descriptive hostname
export VOLODYSLAV_HOSTNAME="my-laptop"

# A fully qualified domain name
export VOLODYSLAV_HOSTNAME="server01.prod.example.com"

VOLODYSLAV_HOSTNAME is a required environment variable. Volodyslav will refuse to start if it is not set (it is checked by ensureEnvironmentIsInitialized at startup).

Why Not Use os.hostname()?​

While Node.js exposes the system hostname via os.hostname(), relying on the OS hostname has several drawbacks:

  • Not portable across environments: The OS hostname may change due to infrastructure automation (e.g., cloud instances getting new names on restart).
  • Ambiguity in containers: Containerized Volodyslav instances may share the same OS-level hostname or have non-descriptive auto-generated names.
  • Explicit is better than implicit: Requiring the operator to set VOLODYSLAV_HOSTNAME forces a conscious choice and makes the deployment more self-documenting.

By requiring an explicit environment variable, you can assign a stable, human-meaningful identifier regardless of the underlying infrastructure.

Visibility in the REST API​

The createdBy field is exposed through the graph inspection REST API alongside createdAt and modifiedAt:

{
  "head": "all_events",
  "args": [],
  "freshness": "up-to-date",
  "createdAt": "2026-03-07T10:18:20.735Z",
  "modifiedAt": "2026-03-07T10:18:20.735Z",
  "createdBy": "my-server.example.com"
}

This makes it easy to see, from outside, which host initially computed each graph node.

VOLODYSLAV_ANALYZER_HOSTNAME

Purpose​

VOLODYSLAV_ANALYZER_HOSTNAME designates which host is responsible for running the diary summary pipeline. Only the host whose VOLODYSLAV_HOSTNAME matches VOLODYSLAV_ANALYZER_HOSTNAME will execute the AI-powered diary summarization.

Behavior​

  • Hourly scheduled job: If the current host is not the analyzer, the diary summary step is skipped and an info-level log entry is written instead.
  • Manual trigger (frontend): If the current host is not the analyzer, the POST /diary-summary/run endpoint returns a 503 response with { "error": "not_analyzer", "currentHostname": "...", "analyzerHostname": "..." }. The frontend displays an error toast with the analyzer hostname.

Configuration​

Set VOLODYSLAV_ANALYZER_HOSTNAME to the hostname of the machine that should run diary summaries:

export VOLODYSLAV_ANALYZER_HOSTNAME="analyzer-host"

VOLODYSLAV_ANALYZER_HOSTNAME is a required environment variable. Volodyslav will refuse to start if it is not set (it is checked by ensureEnvironmentIsInitialized at startup).