Logging

All Miden node services write compact, structured logs to standard output. Long-running services can also export OpenTelemetry traces. The stdout and OpenTelemetry outputs have independent filters, so operators can keep local logs concise while retaining more detail in a tracing backend.

Stdout filter

The stdout filter is selected from the first non-empty value in this order:

1. MIDEN_STDOUT_FILTER
2. RUST_LOG
3. info,user=debug (default)

MIDEN_STDOUT_FILTER uses the tracing_subscriber filter syntax. A filter is a comma-separated list of directives. Each directive sets a level globally or for a target:

target=level

The available levels are off, error, warn, info, debug, and trace. Target directives match a target and its children, so user=info applies to every user::* target.

For example, keep third-party and internal output at warn, show user-facing events at info, and enable detailed RPC events:

MIDEN_STDOUT_FILTER='warn,user=info,user::miden-rpc=debug' \
miden-node full ...

To temporarily enable all debug logs:

MIDEN_STDOUT_FILTER=debug miden-node full ...

To configure a container, pass the filter as an environment variable:

docker run --rm \
  -e MIDEN_STDOUT_FILTER='warn,user=info,user::miden-rpc=debug' \
  ghcr.io/0xmiden/miden-node:<release-tag> \
  miden-node full ...

For systemd, set the same value in the service unit or an environment file, then restart the service:

[Service]
Environment="MIDEN_STDOUT_FILTER=warn,user=info,user::miden-rpc=debug"

RUST_LOG is a compatibility fallback. Prefer MIDEN_STDOUT_FILTER when configuring stdout independently from OpenTelemetry.

User-facing targets

The user::* targets contain events intended for operators. They are enabled at debug by the default stdout filter. The compact stdout format does not print the target name, but the filter still matches it.

info is intended for production use, such as on the sequencer of a Miden network, where detailed per-call or per-transaction messages would create undesirable noise. Events whose primary use case is local development therefore use the debug level, even when they are user-visible. The default info,user=debug stdout filter keeps production events at info while still printing user-visible debug events.

Target	Events
user::miden-node	Node command startup, bootstrap, and recovery
user::miden-rpc	Public RPC requests, subscriptions, readiness, and submissions
user::miden-block-producer	Sequencing, batches, blocks, mempool activity, and synchronization
user::miden-store	Persistence and account, note, and storage lifecycle events
user::miden-validator	Validator startup, bootstrap, validation, and block signing
user::miden-ntx-builder	Network transaction construction and account actor activity
user::miden-prover	Remote prover lifecycle events
user::miden-network-monitor	Network monitor checks and end-to-end probes

A miden-node process contains multiple components. For example, a sequencer can emit user::miden-node, user::miden-rpc, user::miden-block-producer, and user::miden-store events.

OpenTelemetry filter

OpenTelemetry export is enabled when either OTEL_EXPORTER_OTLP_TRACES_ENDPOINT or OTEL_EXPORTER_OTLP_ENDPOINT has a non-empty value. Its filter is selected independently from the first non-empty value in this order:

1. MIDEN_OTEL_FILTER
2. RUST_LOG
3. info,axum::rejection=trace (default)

For example, retain debug-level user-facing events in the tracing backend while keeping stdout quieter:

MIDEN_STDOUT_FILTER='warn,user=info' \
MIDEN_OTEL_FILTER='info,user=debug' \
OTEL_EXPORTER_OTLP_ENDPOINT=http://collector:4317 \
miden-node full ...

If neither Miden-specific filter is set, RUST_LOG configures both outputs. See Monitoring for exporter and resource configuration.

Troubleshooting filters

Start with a narrow target instead of enabling trace globally:

# RPC request and subscription details
MIDEN_STDOUT_FILTER='info,user=debug,user::miden-rpc=trace' miden-node full ...

# Block production and mempool details
MIDEN_STDOUT_FILTER='info,user::miden-block-producer=debug' miden-node sequencer ...

# Store lifecycle and persistence details
MIDEN_STDOUT_FILTER='info,user::miden-store=debug' miden-node full ...

Filters are read only during process startup. Restart the service after changing an environment variable.