Add well-known fallback path for benchmark.json

Read /opt/comfyui-api-wrapper/workflows/pyworker_benchmark.json when
neither misc/benchmark.json nor $BENCHMARK_JSON_PATH yields a usable
file. The vast.ai ComfyUI base image's convert-workflows.sh maintains
that path as a symlink to the first provisioned workflow, so on that
image the operator does not need to set BENCHMARK_JSON_PATH at all.

A set-but-broken $BENCHMARK_JSON_PATH now warns and falls through to
the well-known path instead of dropping straight to the SD1.5 fallback,
so a typo in the env var doesn't mask an otherwise-working benchmark.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

workers/comfyui-json/README.md

@@ -106,11 +106,13 @@ Images will be saved locally AND uploaded to `s3://{bucket}/comfyui/{filename}`.
 
 You can provide a custom ComfyUI workflow for benchmarking. This allows you to test performance using your preferred models and workflow complexity.
 
-**Ways to provide the benchmark file:**
+**Ways to provide the benchmark file** (in resolution order — first match wins):
-- **Fork this repository** and commit your workflow to `workers/comfyui-json/misc/benchmark.json`.
-- **Write the file during provisioning** to a path *outside* the pyworker tree (e.g. `/workspace/benchmark.json`) and export `BENCHMARK_JSON_PATH` so the worker can find it. The pyworker repo is cloned by `start_server.sh` *after* provisioning runs, so provisioning cannot write into `misc/` directly — the destination would be clobbered, or the clone would fail.
 
-If both are present, the in-tree `misc/benchmark.json` wins; `BENCHMARK_JSON_PATH` is consulted only when no in-tree file exists. If the env var is set but points at a missing or unreadable file, the worker logs a warning and falls back to the default benchmark.
+1. **Fork this repository** and commit your workflow to `workers/comfyui-json/misc/benchmark.json`.
+2. **Write the file during provisioning** to a path *outside* the pyworker tree (e.g. `/workspace/benchmark.json`) and export `BENCHMARK_JSON_PATH` so the worker can find it. The pyworker repo is cloned by `start_server.sh` *after* provisioning runs, so provisioning cannot write into `misc/` directly — the destination would be clobbered, or the clone would fail.
+3. **Run on the vast.ai ComfyUI base image.** Its `convert-workflows.sh` maintains `/opt/comfyui-api-wrapper/workflows/pyworker_benchmark.json` as a symlink to the first provisioned workflow; the worker reads this automatically when neither of the above is set. No env var required.
+
+If `BENCHMARK_JSON_PATH` is set but points at a missing or unreadable file, the worker logs a warning and falls through to the next tier rather than going straight to the SD1.5 fallback.
 
 An example workflow is provided at `workers/comfyui-json/misc/benchmark.json.example`. To ensure varied generations, use the placeholder `__RANDOM_INT__` in place of static seed values — it will be replaced with a random integer for each benchmark run.
 
@@ -122,7 +124,7 @@ The default benchmark uses Stable Diffusion v1.5 with ComfyUI's standard text-to
 
 | Environment Variable | Default Value | Description |
 | -------------------- | ------------- | ----------- |
-| BENCHMARK_JSON_PATH | (unset) | Path to a custom workflow file outside the pyworker tree. Used only if `misc/benchmark.json` is absent. |
+| BENCHMARK_JSON_PATH | (unset) | Path to a custom workflow file outside the pyworker tree. Used if `misc/benchmark.json` is absent. Falls through to `/opt/comfyui-api-wrapper/workflows/pyworker_benchmark.json` if set but missing. |
 | BENCHMARK_TEST_WIDTH | 512 | Fallback benchmark: image width (pixels) |
 | BENCHMARK_TEST_HEIGHT | 512 | Fallback benchmark: image height (pixels) |
 | BENCHMARK_TEST_STEPS | 20 | Fallback benchmark: number of denoising steps |

workers/comfyui-json/worker.py

@@ -10,7 +10,12 @@ Each worker runs a benchmark on warm-up. The payload is selected as follows:
      runs before pyworker is cloned, so it cannot write into ``misc/``,
      but it can drop the workflow elsewhere (e.g. ``/workspace/``) and
      export this env var.
-  3. Otherwise an SD1.5 Text2Image fallback runs, parameterised by the
+  3. Else, if the well-known path
+     ``/opt/comfyui-api-wrapper/workflows/pyworker_benchmark.json`` exists,
+     it is used. The vast.ai ComfyUI base image's ``convert-workflows.sh``
+     maintains this as a symlink to the first provisioned workflow, so on
+     that image no env var is needed.
+  4. Otherwise an SD1.5 Text2Image fallback runs, parameterised by the
      ``BENCHMARK_TEST_{WIDTH,HEIGHT,STEPS}`` env vars and a random prompt
      from ``misc/test_prompts.txt``.
 
@@ -55,26 +60,33 @@ MISC_DIR       = Path(__file__).parent / "misc"
 BENCHMARK_FILE = MISC_DIR / "benchmark.json"
 TEST_PROMPTS   = MISC_DIR / "test_prompts.txt"
 
+# Well-known location maintained by the vast.ai ComfyUI base image.
+# convert-workflows.sh symlinks this to the first provisioned workflow,
+# letting the base image work out-of-the-box without any env var.
+WELLKNOWN_BENCHMARK = Path("/opt/comfyui-api-wrapper/workflows/pyworker_benchmark.json")
+
 log = logging.getLogger(__name__)
 
 
 def _resolve_benchmark_path() -> Path | None:
     """Return the path to the custom benchmark workflow, or None if absent.
 
-    See module docstring for the precedence rule. ``$BENCHMARK_JSON_PATH``
+    See module docstring for the precedence rule. A set-but-broken
-    is logged as a warning when set but missing, so a misconfigured
+    ``$BENCHMARK_JSON_PATH`` logs a warning then falls through to the
-    provisioning script doesn't silently degrade to the fallback benchmark.
+    well-known path, so a typo in the env var doesn't silently mask a
+    provisioned benchmark sitting at the standard location.
     """
     if BENCHMARK_FILE.exists():
         return BENCHMARK_FILE
     env_path = os.getenv("BENCHMARK_JSON_PATH")
-    if not env_path:
+    if env_path:
-        return None
         path = Path(env_path)
-    if not path.exists():
+        if path.exists():
-        log.warning("BENCHMARK_JSON_PATH=%s does not exist; falling back to default benchmark", path)
-        return None
             return path
+        log.warning("BENCHMARK_JSON_PATH=%s does not exist; trying fallbacks", path)
+    if WELLKNOWN_BENCHMARK.exists():
+        return WELLKNOWN_BENCHMARK
+    return None
 
 
 def _custom_workflow_payload() -> dict | None: