Environment variables

All of these are optional — the defaults are the shape you want in production. A malformed value never silently changes behavior: Cerulion warns and falls back to the documented default.

Logging

Variable	Meaning
`RUST_LOG`	Standard log filter, for example `RUST_LOG=cerulion=info,iceoryx2=warn`. A new workspace’s `.cargo/config.toml` sets a sane default.
`IOX2_LOG_LEVEL`	The transport’s own log filter. New workspaces default it to `error` so framework chatter does not drown out your logs.

Node logs are worth one note of their own. A node runs as a loaded library with its own log dispatcher, so tracing::info! from your tick() goes to stderr while the host’s own logs go to stdout. The filter is RUST_LOG as captured when the graph started, an empty value means info, and RUST_LOG=off silences node-side logs entirely.

Do not install a global tracing subscriber inside node code — the framework installs one before your node runs, and a second install panics and fails the node load. Control output with RUST_LOG instead.

Networking

Variable	Meaning
`CERULION_NETWORK=off`	Run local-only: no gateway process, nothing crosses the machine boundary. Honored by every entry point, and equivalent to `--network off`.
`CERULION_NETD_LISTEN`	The locators the robot’s shared network plane binds, for example `tcp/0.0.0.0:7683`. Set it on a robot that must be discoverable where LAN multicast is blocked; the plane binds nothing on its own.
`CERULION_GATEWAY_PORT`	Override the well-known gateway port (`7683`). Parsed strictly.
`CERULION_ROBOT_IDENTITY`	The robot name announced on the network. Defaults to the hostname.
`CERULION_PEERS`	Extra peer locators to try when discovering robots.

Recording and capture

Variable	Meaning
`CERULION_FLASHBACK=off`	Turn the Flashback capture plane off, so no run holds a rolling window.
`CERULION_FLASHBACK_DIR`	Where captures land. Defaults to `<workspace>/recordings/flashbacks/`.
`CERULION_RECORD_DISCOVERY=off`	With `graph run --record`, record only the graph’s declared topics instead of also discovering other live producers.
`CERULION_RECORD_DISCOVERY_SETTLE_MS`	How long bag creation waits for late producers to appear.

Visualization

Variable	Meaning
`CERULION_VIZD_SOCK`	Path of the control socket the visualization daemon listens on. Set it on both the daemon and its clients to run a scene at a non-default location.

Live-run tuning

These affect how the live loop idles and how work is spread across cores. Reach for them when you are chasing latency, not before.

Variable	Meaning
`CERULION_MONITOR_WAIT`	`1` forces the live-loop CPU park on, `0` disables it. The default is on for live runs. `--no-monitor-wait` beats this in both directions.
`CERULION_DOORBELL`	`1` forces the data doorbell on (a publish wakes a parked consumer immediately), `0` leaves a timer-only park. Linux only.
`CERULION_CPU_DMA_LOCK`	`1` pins the CPU out of deep idle states, `0` disables the cap. By default Cerulion derives a cap from the graph’s own tightest timing. Linux only, and it needs privileges — a failed acquire warns and the run continues.
`CERULION_CPU_DMA_LOCK_US`	An explicit idle exit-latency cap in microseconds, used under the automatic mode.
`CERULION_FIRE_THREADS`	Size of the pool that fires independent nodes within one level. Read once at graph build; the default is derived from the machine and the graph’s widest level. It never changes what fires or in what order.
`CERULION_BARRIER_SPIN_US`	Multi-process only: how long a worker waits actively at each level boundary before it sleeps. `0` skips the active wait. Values above 100 ms are clamped with a warning.
`CERULION_BARRIER_OS_SYNC`	macOS only: `0` opts out of the faster wake path at level boundaries, at the cost of latency.

Build

Variable	Meaning
`CARGO_TARGET_DIR`	Honored identically by `cerulion node build` and `cerulion graph run`, so a shared target directory works.

CLI reference

The flags that override several of these variables.

Network a graph

What the network variables change in practice.

Get started

Concepts

Guides

Reference

Logging

Networking

Recording and capture

Visualization

Live-run tuning

Build

CLI reference

Network a graph

​Logging

​Networking

​Recording and capture

​Visualization

​Live-run tuning

​Build

​Related

CLI reference

Network a graph

Logging

Networking

Recording and capture

Visualization

Live-run tuning

Build

Related