Configuration

Configuration

Every setting can be set in a YAML config file, in the environment, or on the command line, and a later one wins: default < config < env < args. A setting's file path is its name: redis.host is REDIS_HOST and --redis-host.

The file is named by --config-file or CONFIG_FILE. There is no default location. A file with an unknown key stops the server with the reason.

server

Where it listens, and where it lives.

Config	Env	Flag	Default	What
config_file	CONFIG_FILE	--config-file	—	The YAML file read at start.
transport	TRANSPORT	--transport	http	http, or stdio for one local client.
host	HOST	--host	0.0.0.0	Address to listen on.
port	PORT	--port	8000	Port to listen on.
log_level	LOG_LEVEL	--log-level	INFO	DEBUG, INFO, WARNING or ERROR.
route_prefix	ROUTE_PREFIX	--route-prefix	/	Path the whole server is mounted under.
public_base_url	PUBLIC_BASE_URL	--public-base-url	—	Where browsers reach this server, for links.

auth

The bearer token every request needs.

Config	Env	Flag	Default	What
auth.token	AUTH_TOKEN	--auth-token	—	Bearer token for every request. Unset is open. Sensitive.

grid

The Selenium Grid it drives.

Config	Env	Flag	Default	What
grid.url	GRID_URL	--grid-url	http://selenium-grid-selenium-hub.flow.svc.cluster.local:4444	The Selenium Grid hub.
grid.console_url	GRID_CONSOLE_URL	--grid-console-url	/	Where the Grid console tab is framed from.

session

How sessions are kept, and how new browsers open.

Config	Env	Flag	Default	What
session.store	SESSION_STORE	--session-store	memory	memory; redis.host or redis.url switches it to redis.
session.ttl	SESSION_TTL	--session-ttl	86400	Seconds a session is kept after its last use.
session.browser	SESSION_BROWSER	--session-browser	—	chrome or firefox, for new sessions.
session.width	SESSION_WIDTH	--session-width	—	Window width for new sessions.
session.height	SESSION_HEIGHT	--session-height	—	Window height for new sessions.
session.page_load_timeout	SESSION_PAGE_LOAD_TIMEOUT	--session-page-load-timeout	—	Seconds a page may take to load.
session.script_timeout	SESSION_SCRIPT_TIMEOUT	--session-script-timeout	—	Seconds a script may run.

redis

The session store’s connection.

Config	Env	Flag	Default	What
redis.url	REDIS_URL	--redis-url	—	A full Redis URL, instead of host and port. Sensitive.
redis.host	REDIS_HOST	--redis-host	localhost	Redis host.
redis.port	REDIS_PORT	--redis-port	6379	Redis port.
redis.db	REDIS_DB	--redis-db	0	Redis database number.
redis.username	REDIS_USERNAME	--redis-username	—	Redis username.
redis.password	REDIS_PASSWORD	--redis-password	—	Redis password. Sensitive.
redis.ssl	REDIS_SSL	--redis-ssl	false	Connect to Redis over TLS.
redis.prefix	REDIS_PREFIX	--redis-prefix	selenium-flow:session:	Prefix on every key, so a shared database is safe.

flow

Saved flows and kept files.

Config	Env	Flag	Default	What
flow.data_dir	FLOW_DATA_DIR	--flow-data-dir	—	Where flows and kept files live. Unset turns flows off.

secrets

Where secrets are read from.

Config	Env	Flag	Default	What
secrets.dirs	SECRETS_DIRS	--secrets-dirs	—	Directories of secrets. First match wins.

mcp

What MCP clients are offered beyond tools.

Config	Env	Flag	Default	What
mcp.skill	MCP_SKILL	--mcp-skill	true	Serve the agent skill as resources.
mcp.apps	MCP_APPS	--mcp-apps	true	Offer MCP Apps views.

---

One value in each place

# /etc/selenium-flow/config.yaml
session:
  ttl: 86400
redis:
  host: redis.data
  db: 2

export CONFIG_FILE=/etc/selenium-flow/config.yaml
export GRID_URL=http://selenium-hub:4444
selenium-flow --log-level DEBUG

The Settings tab of the admin UI shows every value and where it came from.

Worth setting

session.page_load_timeout: with no bound, one hung page holds a Grid slot until the Grid reaps it.

The environment is lenient, the file is not

An environment variable the server does not know is ignored: Kubernetes injects <SERVICE>_PORT variables into every pod. A key the file does not know stops the boot, because it is a typo.

The exception: a Kubernetes Service literally named redis injects REDIS_PORT=tcp://…, which is a known leaf and stops the boot on a value that was never meant as one. Hence enableServiceLinks: false on the pod.

Lists and booleans in env and flags

secrets.dirs splits like PATH, on the OS path separator (:). A boolean setting accepts true/false, 1/0, yes/no and on/off.

Secrets

The file's secrets.entries section defines secrets. See Secrets.