Env var reference

Complete list. See Environment variables for where to set them and how precedence works. The HERMES_OTEL_* table is generated from HermesOtelConfig by scripts/gen_config_docs.py; a test fails if it drifts.

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
LANGSMITH_WORKSPACE_ID	string	LangSmith workspace id header (multi-workspace orgs)
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 fallback; does not enable Langfuse in env-var mode on its own)
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)
OTEL_UPTRACE_ENDPOINT	URL	Uptrace OTLP endpoint; enables Uptrace in env-var mode
OTEL_UPTRACE_DSN / UPTRACE_DSN	DSN	Uptrace DSN (uptrace-dsn header)
OTEL_OPENOBSERVE_ENDPOINT	URL	OpenObserve .../api/<org>/v1/traces; enables OpenObserve in env-var mode
OTEL_OPENOBSERVE_USER / OPENOBSERVE_USER	string	OpenObserve Basic-auth user
OTEL_OPENOBSERVE_PASSWORD / OPENOBSERVE_PASSWORD	string	OpenObserve Basic-auth password
OTEL_OPENOBSERVE_STREAM	string	Optional OpenObserve stream name
OTEL_PARSEABLE_ENDPOINT	URL	Parseable ingestor .../v1/traces; enables Parseable in env-var mode
OTEL_PARSEABLE_API_KEY / PARSEABLE_API_KEY	string	Parseable API key
PARSEABLE_TRACES_DATASET / PARSEABLE_METRICS_DATASET / PARSEABLE_LOGS_DATASET	string	Parseable dataset per signal (defaults hermes-traces / hermes-metrics / hermes-logs)
OTEL_ELASTIC_ENDPOINT	URL	Elastic OTLP endpoint (Elastic Cloud mOTLP or EDOT Collector); enables Elastic in env-var mode
OTEL_ELASTIC_API_KEY	string	Elastic API key (Authorization: ApiKey); needs OTEL_ELASTIC_ENDPOINT to enable Elastic in env-var mode (there is no default host)
ELASTIC_API_KEY	string	Elastic API key fallback; does not enable Elastic in env-var mode on its own
OTEL_OPENLIT_ENDPOINT	URL	OpenLIT OTLP/HTTP receiver base (http://localhost:4338 for the bundled stack); enables OpenLIT in env-var mode
OTEL_OPENLIT_API_KEY	string	OpenLIT API key (Authorization: Bearer); optional, needs OTEL_OPENLIT_ENDPOINT to enable OpenLIT in env-var mode
OPENLIT_API_KEY	string	OpenLIT API key fallback; does not enable OpenLIT in env-var mode on its own
OTEL_MLFLOW_ENDPOINT	URL	MLflow tracking server (http://localhost:5001 for the bundled stack); enables MLflow in env-var mode
OTEL_MLFLOW_EXPERIMENT_ID / MLFLOW_EXPERIMENT_ID	string	Experiment for the mandatory x-mlflow-experiment-id header (default 0, the Default experiment)
OTEL_MLFLOW_API_KEY / MLFLOW_TRACKING_TOKEN	string	Tracking token (Authorization: Bearer); optional, does not enable MLflow on its own
OTEL_OPIK_ENDPOINT	URL	Opik base URL (http://localhost:5173 for the bundled stack; default Comet cloud); enables Opik in env-var mode
OTEL_OPIK_API_KEY	string	Opik API key (bare Authorization header); enables Opik in env-var mode (cloud default host)
OPIK_API_KEY / OPIK_URL_OVERRIDE / OPIK_WORKSPACE / OPIK_PROJECT_NAME	string	Opik SDK variables used as fallbacks for the key, base URL, Comet-Workspace and projectName; never enable export on their own
OTEL_LAMINAR_API_KEY	string	Laminar project API key (Authorization: Bearer); enables Laminar in env-var mode (cloud default host)
OTEL_LAMINAR_ENDPOINT	URL	Laminar app-server base (http://localhost:8100 for the bundled stack); needs a key to resolve
LMNR_PROJECT_API_KEY / LMNR_BASE_URL	string	Laminar SDK variables used as fallbacks for the key and base URL; never enable export on their own
OTEL_LANGWATCH_API_KEY	string	LangWatch project API key (sk-lw-…, Authorization: Bearer); enables LangWatch in env-var mode (cloud default host)
OTEL_LANGWATCH_ENDPOINT	URL	LangWatch base (http://localhost:5560 for the bundled stack); needs a key to resolve
LANGWATCH_API_KEY / LANGWATCH_ENDPOINT / LANGWATCH_PROJECT_ID	string	LangWatch SDK variables used as fallbacks for the key, base URL and X-Project-Id; never enable export on their own
OTEL_LATITUDE_API_KEY	string	Latitude API key (Authorization: Bearer); enables Latitude in env-var mode together with LATITUDE_PROJECT (cloud default host)
OTEL_LATITUDE_ENDPOINT	URL	Latitude ingest base (http://localhost:3002 for the bundled stack); needs a key and project to resolve
LATITUDE_API_KEY / LATITUDE_PROJECT / LATITUDE_INGEST_URL	string	Latitude variables used for the key, the mandatory X-Latitude-Project slug and the ingest URL; never enable export on their own
OTEL_HONEYCOMB_API_KEY	hcaik_...	Honeycomb ingest key (x-honeycomb-team); enables Honeycomb in env-var mode
HONEYCOMB_API_KEY	hcaik_...	Honeycomb key fallback; does not enable Honeycomb in env-var mode on its own
OTEL_HONEYCOMB_ENDPOINT	URL	Honeycomb endpoint override (default: US region)
OTEL_WEAVE_API_KEY	string	W&B API key (plugin-specific); enables Weave in env-var mode when routing vars are also set
WANDB_API_KEY	string	W&B API key fallback; does not enable Weave in env-var mode on its own
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	openinference.project.name on the Resource (the Phoenix project). service.name is always hermes-agent; override it with resource_attributes:

HERMES_OTEL_* overrides

Every scalar field of the config file can be overridden by HERMES_OTEL_<FIELD> (upper-case field name). Maps (headers, global_tags, resource_attributes) and backends are yaml-only. An env var that cannot be parsed as the field's type logs a warning and is ignored.

Env var	Maps to	Type	Default
HERMES_OTEL_ENABLED	enabled	bool	true
HERMES_OTEL_SAMPLE_RATE	sample_rate	float	null
HERMES_OTEL_ROOT_SPAN_TTL_MS	root_span_ttl_ms	int	600000
HERMES_OTEL_FLUSH_INTERVAL_MS	flush_interval_ms	int	60000
HERMES_OTEL_PREVIEW_MAX_CHARS	preview_max_chars	int	1200
HERMES_OTEL_CAPTURE_PREVIEWS	capture_previews	bool	true
HERMES_OTEL_TOOL_INPUT_PREVIEW_MAX_CHARS	tool_input_preview_max_chars	int	null
HERMES_OTEL_TOOL_OUTPUT_PREVIEW_MAX_CHARS	tool_output_preview_max_chars	int	null
HERMES_OTEL_LLM_INPUT_PREVIEW_MAX_CHARS	llm_input_preview_max_chars	int	null
HERMES_OTEL_LLM_OUTPUT_PREVIEW_MAX_CHARS	llm_output_preview_max_chars	int	null
HERMES_OTEL_PROJECT_NAME	project_name	string	(unset)
HERMES_OTEL_SPAN_BATCH_MAX_QUEUE_SIZE	span_batch_max_queue_size	int	2048
HERMES_OTEL_SPAN_BATCH_SCHEDULE_DELAY_MS	span_batch_schedule_delay_ms	int	1000
HERMES_OTEL_SPAN_BATCH_MAX_EXPORT_BATCH_SIZE	span_batch_max_export_batch_size	int	null
HERMES_OTEL_SPAN_BATCH_EXPORT_TIMEOUT_MS	span_batch_export_timeout_ms	int	30000
HERMES_OTEL_FORCE_FLUSH_ON_SESSION_END	force_flush_on_session_end	bool	true
HERMES_OTEL_FORCE_FLUSH_WAIT_MS	force_flush_wait_ms	int	1500
HERMES_OTEL_CAPTURE_CONVERSATION_HISTORY	capture_conversation_history	bool	false
HERMES_OTEL_CONVERSATION_HISTORY_MAX_CHARS	conversation_history_max_chars	int	20000
HERMES_OTEL_CONTENT_CAPTURE	content_capture	string	"full"
HERMES_OTEL_CAPTURE_FULL_PROMPTS	capture_full_prompts	bool	true
HERMES_OTEL_CAPTURE_FULL_RESPONSES	capture_full_responses	bool	true
HERMES_OTEL_CAPTURE_SENDER_ID	capture_sender_id	bool	false
HERMES_OTEL_CAPTURE_LOGS	capture_logs	bool	false
HERMES_OTEL_LOG_LEVEL	log_level	string	"INFO"
HERMES_OTEL_LOG_ATTACH_LOGGER	log_attach_logger	string	(unset)
HERMES_OTEL_LOG_ONLY_IN_TURN	log_only_in_turn	bool	false
HERMES_OTEL_LOG_MAX_ATTRIBUTE_LENGTH	log_max_attribute_length	int	4096
HERMES_OTEL_LOG_BATCH_SCHEDULE_DELAY_MS	log_batch_schedule_delay_ms	int	1000
HERMES_OTEL_LOG_BATCH_MAX_QUEUE_SIZE	log_batch_max_queue_size	int	2048
HERMES_OTEL_LOG_BATCH_MAX_EXPORT_BATCH_SIZE	log_batch_max_export_batch_size	int	512
HERMES_OTEL_LOG_BATCH_EXPORT_TIMEOUT_MS	log_batch_export_timeout_ms	int	30000
HERMES_OTEL_LOG_LIVE_MIN_LEVEL	log_live_min_level	string	"INFO"
HERMES_OTEL_LOG_EVENTS	log_events	bool	false
HERMES_OTEL_LOG_EVENTS_CONTENT	log_events_content	string	"inherit"
HERMES_OTEL_EMIT_GENAI_METRICS	emit_genai_metrics	bool	true
HERMES_OTEL_METRICS_TEMPORALITY	metrics_temporality	string	(unset)
HERMES_OTEL_METRICS_HISTOGRAM	metrics_histogram	string	"explicit"
HERMES_OTEL_METRICS_LABEL_LIMIT	metrics_label_limit	int	100
HERMES_OTEL_SKILL_SPANS	skill_spans	bool	true
HERMES_OTEL_DISCOVERY_PROMPT	discovery_prompt	bool	false
HERMES_OTEL_DASHBOARD_LIVE	dashboard_live	bool	true
HERMES_OTEL_DASHBOARD_LIVE_MAX_SPANS	dashboard_live_max_spans	int	1000
HERMES_OTEL_DASHBOARD_LIVE_RETENTION_HOURS	dashboard_live_retention_hours	float	168.0
HERMES_OTEL_HOST_METRICS	host_metrics	bool	false
HERMES_OTEL_HOST_METRICS_GPU	host_metrics_gpu	string	"auto"
HERMES_OTEL_HOST_METRICS_INTERVAL_MS	host_metrics_interval_ms	int	1000
HERMES_OTEL_SUPPRESS_MCP_PING_SPANS	suppress_mcp_ping_spans	bool	true

Paths

Var	Effect
HERMES_OTEL_CONFIG	Explicit path to the config file; highest precedence — see Where does the config live?
HERMES_HOME	Hermes' home (default ~/.hermes); the plugin resolves hermes_otel.yaml, the live store and the debug log under it. Inside a multiplexed gateway each profile's plugin uses that profile's home instead, via Hermes's own resolver (profiles)
HERMES_OTEL_LIVE_DB	Path of the live dashboard's SQLite store (default $HERMES_HOME/hermes_otel_live.db)

Debug

Var	Value	Effect
HERMES_OTEL_DEBUG	true/false	Enables the debug log at $HERMES_HOME/plugins/hermes_otel/debug.log (~/.hermes by default)

Boolean accepted values

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

Case-insensitive. Anything else logs a warning naming the variable and is ignored (the yaml value or default is kept).