Env var reference

Complete list. See Environment variables for the narrative version.

Backend selection

Var	Value	Effect
LANGSMITH_TRACING	true/false	Enables LangSmith backend
LANGSMITH_API_KEY	lsv2_...	LangSmith auth
LANGSMITH_ENDPOINT	URL	LangSmith endpoint (default: https://api.smith.langchain.com)
LANGSMITH_PROJECT	string	LangSmith project name
OTEL_LANGFUSE_PUBLIC_API_KEY	pk-lf-...	Langfuse public key (plugin-specific)
OTEL_LANGFUSE_SECRET_API_KEY	sk-lf-...	Langfuse secret key (plugin-specific)
OTEL_LANGFUSE_ENDPOINT	URL	Langfuse OTLP endpoint
LANGFUSE_PUBLIC_KEY	pk-lf-...	Langfuse public key (SDK-standard)
LANGFUSE_SECRET_KEY	sk-lf-...	Langfuse secret key (SDK-standard)
LANGFUSE_BASE_URL	URL	Langfuse base URL (SDK-standard)
OTEL_SIGNOZ_ENDPOINT	URL	SigNoz OTLP endpoint (self-host: http://localhost:4328/v1/traces)
OTEL_SIGNOZ_INGESTION_KEY	sz-...	SigNoz Cloud ingestion key
OTEL_JAEGER_ENDPOINT	URL	Jaeger OTLP endpoint (http://localhost:4318/v1/traces)
OTEL_TEMPO_ENDPOINT	URL	Tempo OTLP endpoint
OTEL_PHOENIX_ENDPOINT	URL	Phoenix OTLP endpoint (http://localhost:6006/v1/traces)
HONEYCOMB_API_KEY	hcaik_...	Honeycomb ingest key (x-honeycomb-team); enables Honeycomb in env-var mode
OTEL_HONEYCOMB_API_KEY	hcaik_...	Honeycomb key (plugin-specific alias)
OTEL_HONEYCOMB_ENDPOINT	URL	Honeycomb endpoint override (default: US region)
WANDB_API_KEY	string	W&B API key; enables Weave in env-var mode when routing vars are also set
WANDB_ENTITY	string	W&B entity/team for Weave routing (wandb.entity)
WANDB_PROJECT	string	W&B project for Weave routing (wandb.project)
DEFAULT_WANDB_ENTITY	string	Weave entity fallback, useful with an OTel Collector
DEFAULT_WANDB_PROJECT	string	Weave project fallback, useful with an OTel Collector
OTEL_WEAVE_ENDPOINT	URL	Full Weave OTLP traces endpoint override
WANDB_OTLP_ENDPOINT	URL	Weave OTLP endpoint alias used by W&B docs
OTEL_WEAVE_BASE_URL	URL	W&B base URL; plugin appends the trace ingest path
WANDB_BASE_URL	URL	W&B base URL alias for Dedicated Cloud / Self-Managed
OTEL_PROJECT_NAME	string	Resource service.name + openinference.project.name

Shaping overrides

Var	Maps to	Default
HERMES_OTEL_ENABLED	enabled	true
HERMES_OTEL_SAMPLE_RATE	sample_rate	null (AlwaysOn)
HERMES_OTEL_ROOT_SPAN_TTL_MS	root_span_ttl_ms	600000 (10 min)
HERMES_OTEL_FLUSH_INTERVAL_MS	flush_interval_ms	60000 (60s)
HERMES_OTEL_PREVIEW_MAX_CHARS	preview_max_chars	1200
HERMES_OTEL_CAPTURE_PREVIEWS	capture_previews	true
HERMES_OTEL_CAPTURE_CONVERSATION_HISTORY	capture_conversation_history	false
HERMES_OTEL_CONVERSATION_HISTORY_MAX_CHARS	conversation_history_max_chars	20000
HERMES_OTEL_PROJECT_NAME	project_name	(unset)
HERMES_OTEL_SPAN_BATCH_MAX_QUEUE_SIZE	span_batch_max_queue_size	2048
HERMES_OTEL_SPAN_BATCH_SCHEDULE_DELAY_MS	span_batch_schedule_delay_ms	1000
HERMES_OTEL_SPAN_BATCH_MAX_EXPORT_BATCH_SIZE	span_batch_max_export_batch_size	512
HERMES_OTEL_SPAN_BATCH_EXPORT_TIMEOUT_MS	span_batch_export_timeout_ms	30000
HERMES_OTEL_FORCE_FLUSH_ON_SESSION_END	force_flush_on_session_end	true

Logs

See OTel logs for behavior.

Var	Maps to	Default
HERMES_OTEL_CAPTURE_LOGS	capture_logs	false
HERMES_OTEL_LOG_LEVEL	log_level	INFO
HERMES_OTEL_LOG_ATTACH_LOGGER	log_attach_logger	(unset = root)

Debug

Var	Value	Effect
HERMES_OTEL_DEBUG	true/false	Enables debug log at ~/.hermes/plugins/hermes_otel/debug.log

Boolean accepted values

True	False
true / 1 / yes / on	false / 0 / no / off / ""

Case-insensitive. Anything else → warning + fallback to default.