Environment Variables Configuration

hotpath behavior can be customized via environment variables. These take precedence over programmatic configuration (hotpath::main macro parameters and builder API).

Output

Variable	Description
`HOTPATH_OUTPUT_FORMAT`	Output format: `table`, `json`, `json-pretty`, or `none`. Using `none` silences output while keeping the metrics server and MCP server active. (default: `table`)
`HOTPATH_OUTPUT_PATH`	File path for profiling reports. Takes precedence over programmatic `output_path` config. (default: `stdout`)
`HOTPATH_REPORT`	Comma-separated sections to include in report: `functions-timing`, `functions-alloc`, `channels`, `streams`, `futures`, `threads`, `tokio_runtime`, or `all`. (default: `functions-timing,functions-alloc,threads`)

Functions

Variable	Description
`HOTPATH_FOCUS`	Filter profiled functions by name. Plain text does substring matching; wrap in `/pattern/` for regex (e.g. `HOTPATH_FOCUS="/^(compute\|process)/"`). (default: `''`)
`HOTPATH_EXCLUDE_WRAPPER`	Set to `true` or `1` to calculate ratios using the sum of measured functions instead of the wrapper total. (default: `false`)
`HOTPATH_ALLOC_SELF`	Set to `true` or `1` to track exclusive (non-cumulative) memory allocations per function instead of the default cumulative mode. (default: `false`)
`HOTPATH_CPU_BASELINE_OFF`	Set to `true` or `1` to disable CPU baseline collection. (default: `false`)

Metrics Server

Variable	Description
`HOTPATH_METRICS_PORT`	Port for the HTTP metrics server (binds to `localhost` only). (default: `6770`)
`HOTPATH_METRICS_SERVER_OFF`	Set to `true` or `1` to disable the HTTP metrics server entirely. (default: `false`)

MCP Server

Variable	Description
`HOTPATH_MCP_PORT`	Port for the MCP (Model Context Protocol) server. (default: `6771`)
`HOTPATH_MCP_AUTH_TOKEN`	When set, clients must include this token in the `Authorization` header. (default: `''`)

TUI

Variable	Description
`HOTPATH_TUI_REFRESH_INTERVAL_MS`	TUI dashboard refresh interval in milliseconds. (default: `500`)
`HOTPATH_TUI_TAB`	Initial tab to display when launching the TUI (e.g. `functions`, `channels`, `streams`). Useful for self-benchmarks. (default: `''`)
`HOTPATH_METRICS_HOST`	Host URL that the TUI console connects to for metrics data. (default: `http://localhost`)
`HOTPATH_METRICS_PORT`	Port that the TUI console connects to for metrics data. (default: `6770`)

Other

Variable	Description
`HOTPATH_THREADS_INTERVAL`	Thread monitoring sample interval in milliseconds. (default: `1000`)
`HOTPATH_TOKIO_RUNTIME_INTERVAL`	Tokio runtime metrics sampling interval in milliseconds. (default: `1000`)
`HOTPATH_LOGS_LIMIT`	Maximum number of log entries to keep per channel, stream, or function. (default: `50`)
`HOTPATH_SHUTDOWN_MS`	If set a profiled program will shutdown after the specified ms timeout and print the performance report. (default: `''`). Use `before_shutdown` to specify before shutdown callback.