decouple prediction strategy from env variable

docs/deploy.md

@@ -28,6 +28,3 @@ The following variables should be exposed to the container. Those **bolded** are
 - **`GITLAB_API_TOKEN`** - this token should have API read access
 - **`GITLAB_WEBHOOK_TOKEN`** - coordinate this value with the collection webhook
 - **`DB_FILE`** - path where the application can access the SQLite file
-- `PREDICT_STRATEGY` - optional mode for the prediction algorithm
-    - options: 
-        - `ensure_higher`: if the predicted resource usage is below current levels, it will disregard the prediction and keep what would be allocated without Gantry's intervention

gantry/routes/prediction/prediction.py

@@ -1,5 +1,4 @@
 import logging
-import os
 
 import aiosqlite
 
@@ -23,13 +22,17 @@
 }
 
 
-async def predict(db: aiosqlite.Connection, spec: dict) -> dict:
+async def predict(db: aiosqlite.Connection, spec: dict, strategy: str = None) -> dict:
     """
     Predict the resource usage of a spec
 
     args:
         spec: dict that contains pkg_name, pkg_version, pkg_variants,
         compiler_name, compiler_version
+        strategy (optional): custom prediction behavior
+            "ensure_higher": if the predicted resource usage is
+            below current levels, it will disregard the prediction and
+            keep what would be allocated without Gantry's intervention
     returns:
         dict of predicted resource usage: cpu_request, mem_request
         CPU in millicore, mem in MB
@@ -51,7 +54,7 @@ async def predict(db: aiosqlite.Connection, spec: dict) -> dict:
             "mem_request": sum([build[2] for build in sample]) / len(sample),
         }
 
-    if os.environ.get("PREDICT_STRATEGY") == "ensure_higher":
+    if strategy == "ensure_higher":
         ensure_higher_pred(predictions, spec["pkg_name"])
 
     # warn if the prediction is below some thresholds
@@ -85,7 +88,7 @@ async def get_sample(db: aiosqlite.Connection, spec: dict) -> list:
     Selects a sample of builds to use for prediction
 
     args:
-        spec: see predict_single
+        spec: see predict
     returns:
         list of lists with cpu_mean, cpu_max, mem_mean, mem_max
     """

gantry/views.py

@@ -6,7 +6,7 @@
 from aiohttp import web
 
 from gantry.routes.collection import fetch_job
-from gantry.routes.prediction.prediction import predict_single
+from gantry.routes.prediction.prediction import predict
 from gantry.util.spec import parse_alloc_spec
 
 logger = logging.getLogger(__name__)
@@ -68,4 +68,7 @@ async def allocation(request: web.Request) -> web.Response:
     if not parsed_spec:
         return web.Response(status=400, text="invalid spec")
 
-    return web.json_response(await predict_single(request.app["db"], parsed_spec))
+    # we want to keep predictions >= current levels (with ensure_higher strategy)
+    return web.json_response(
+        await predict(request.app["db"], parsed_spec, strategy="ensure_higher")
+    )