> For the complete documentation index, see [llms.txt](https://blackprince001.gitbook.io/flowbench-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blackprince001.gitbook.io/flowbench-documentation/reference/environment.md).

# Environment variables

Configuration FlowBench reads from the process environment. Everything here is optional; the defaults are the dev-checkout behavior.

## Authoring and templating

| Variable                      | Read by    | Meaning                                                                                                                                          |
| ----------------------------- | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
| anything via `{{ env.NAME }}` | the engine | injected into templated fields at run time; every value read this way is registered for redaction and appears as `[redacted]` in stored payloads |

## The Python bridge

| Variable                 | Read by                            | Meaning                                                                                                                        |
| ------------------------ | ---------------------------------- | ------------------------------------------------------------------------------------------------------------------------------ |
| `FLOWBENCH_COMPILE_ONLY` | the SDK                            | set by `flowbench run flow.py`: `flow.run()` prints compiled IR instead of executing — not usually set by hand                 |
| `FLOWBENCH_PYTHON`       | `flowbench run`, conformance suite | the Python interpreter to compile `.py` flows with; default is `sdk-python/.venv`'s, then `python3` on `PATH` (3.10+ enforced) |
| `FLOWBENCH_SDK_PATH`     | `flowbench run`                    | where `sdk-python/` lives; the default searches upward from the flow file, which assumes a dev checkout                        |
| `FLOWBENCH_BIN`          | the SDK                            | the `flowbench` binary used to resolve named targets; default is `flowbench` on `PATH`                                         |

## Test and benchmark harnesses

| Variable                   | Read by                    | Meaning                                                                                              |
| -------------------------- | -------------------------- | ---------------------------------------------------------------------------------------------------- |
| `FLOWBENCH_REQUIRE_PYTHON` | conformance suite          | turn "no usable interpreter" from a skip into a failure — CI sets it so green can never mean skipped |
| `FLOWBENCH_BENCH_VUS`      | `TestVUFootprintBenchmark` | VU count for the footprint benchmark (default 1000)                                                  |
| `FLOWBENCH_BENCH_DUR`      | 〃                          | benchmark duration (default 2s)                                                                      |
| `FLOWBENCH_BENCH_LATENCY`  | 〃                          | simulated target latency (default 100ms)                                                             |

The benchmark methodology and reference numbers live in [the 10k-VU footprint doc](broken://pages/E7GWcksnjpUcQECJTDWy).


---

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