feat: add way to generate gateway side OpenAPI spec

This commit gives users a way to generate the OpenAPI spec of the
endpoints created by the https://docs.livepeer.ai/ai/orchestrators/onchain
gateway. The difference is that at that entrypoint the `/health` route
does not exist and the `model_id` is required.

runner/gen_openapi.py

@@ -1,22 +1,64 @@
-from fastapi.openapi.utils import get_openapi
-from app.main import app, use_route_names_as_operation_ids
-from app.routes import health, text_to_image, image_to_image, image_to_video
+import argparse
 import json
+
 import yaml
-import argparse
+from app.main import app, use_route_names_as_operation_ids
+from app.routes import health, image_to_image, image_to_video, text_to_image
+from fastapi.openapi.utils import get_openapi
 
 # Specify Endpoints for OpenAPI schema generation.
 SERVERS = [
-    {"url": "http://gateway-endpoint.ai/", "description": "Example Gateway"},
+    {
+        "url": "https://dream-gateway.livepeer.cloud",
+        "description": "Livepeer Cloud Community Gateway",
+    },
 ]
 
 
-def write_openapi(fname):
+def translate_to_gateway(openapi):
+    """Translate the OpenAPI schema from the 'runner' entrypoint to the 'gateway'
+    entrypoint created by the https://github.com/livepeer/go-livepeer package.
+
+    .. note::
+       Differences between 'runner' and 'gateway' entrypoints:
+       - 'health' endpoint is removed.
+       - 'model_id' is enforced in all endpoints.
+
+    Args:
+        openapi (dict): The OpenAPI schema to be translated.
+
+    Returns:
+        dict: The translated OpenAPI schema.
+    """
+    # Remove 'health' endpoint
+    openapi["paths"].pop("/health")
+
+    # Enforce 'model_id' in all endpoints
+    for _, methods in openapi["paths"].items():
+        for _, details in methods.items():
+            if "requestBody" in details:
+                for _, content_details in details["requestBody"]["content"].items():
+                    if (
+                        "schema" in content_details
+                        and "$ref" in content_details["schema"]
+                    ):
+                        ref = content_details["schema"]["$ref"]
+                        schema_name = ref.split("/")[-1]
+                        schema = openapi["components"]["schemas"][schema_name]
+                        if "model_id" in schema["properties"]:
+                            schema["required"].append("model_id")
+
+    return openapi
+
+
+def write_openapi(fname, entrypoint="runner"):
     """Write OpenAPI schema to file.
 
     Args:
         fname (str): The file name to write to. The file extension determines the file
             type. Either 'json' or 'yaml'.
+        entrypoint (str): The entrypoint to generate the OpenAPI schema for, either
+            'gateway' or 'runner'. Default is 'runner'.
     """
     app.include_router(health.router)
     app.include_router(text_to_image.router)
@@ -25,32 +67,34 @@ def write_openapi(fname):
 
     use_route_names_as_operation_ids(app)
 
+    print(f"Generating OpenAPI schema for '{entrypoint}' entrypoint...")
+    openapi = get_openapi(
+        title="Livepeer AI Runner",
+        version="0.1.0",
+        openapi_version=app.openapi_version,
+        description="An application to run AI pipelines",
+        routes=app.routes,
+        servers=SERVERS,
+    )
+
+    # Translate OpenAPI schema to 'gateway' side entrypoint if requested.
+    if entrypoint == "gateway":
+        print("Translating OpenAPI schema from 'runner' to 'gateway' entrypoint...")
+        openapi = translate_to_gateway(openapi)
+        fname = fname.replace(".yaml", "_gateway.yaml")
+
     # Write OpenAPI schema to file.
     with open(fname, "w") as f:
         print(f"Writing OpenAPI schema to '{fname}'...")
         if fname.endswith(".yaml"):
             yaml.dump(
-                get_openapi(
-                    title="Livepeer AI Runner",
-                    version="0.1.0",
-                    openapi_version=app.openapi_version,
-                    description="An application to run AI pipelines",
-                    routes=app.routes,
-                    servers=SERVERS,
-                ),
+                openapi,
                 f,
                 sort_keys=False,
             )
         else:
             json.dump(
-                get_openapi(
-                    title="Livepeer AI Runner",
-                    version="0.1.0",
-                    openapi_version=app.openapi_version,
-                    description="An application to run AI pipelines",
-                    routes=app.routes,
-                    servers=SERVERS,
-                ),
+                openapi,
                 f,
                 indent=4,  # Make human readable.
             )
@@ -66,6 +110,16 @@ def write_openapi(fname):
         default="json",
         help="File type to write to, either 'json' or 'yaml'. Default is 'json'",
     )
+    parser.add_argument(
+        "--entrypoint",
+        type=str,
+        choices=["gateway", "runner"],
+        default="runner",
+        help=(
+            "The entrypoint to generate the OpenAPI schema for, either 'gateway' or "
+            "'runner'. Default is 'runner'",
+        ),
+    )
     args = parser.parse_args()
 
-    write_openapi(f"openapi.{args.type.lower()}")
+    write_openapi(f"openapi.{args.type.lower()}", args.entrypoint)