Client constructor option, which takes precedence over its environment variable.
Configuration
An empty string is treated the same as unset.
HH_CONTROL_PLANE_API_KEY= node script.js therefore fails construction exactly as an unset key would, and an empty HH_CONTROL_PLANE_URL falls back to the default.
The API key is only required when no middleware is supplied. A client that authenticates entirely through custom middleware can be constructed with no key at all.
These names are distinct from the data plane SDK’s
HH_PROJECT_API_KEY and HH_DATA_PLANE_URL (see its environment variables), so both clients can be configured in the same process without collision. HH_VERBOSE is the one variable they share.