build: centralize pinned base image arguments

bot_bottle/backend/docker/gateway.py

@@ -96,6 +96,11 @@ class DockerGateway(Gateway):
                 str(context)]
         if os.environ.get("BOT_BOTTLE_NO_CACHE"):
             argv.insert(2, "--no-cache")
+        for name, value in resources.image_build_args(
+            self._dockerfile,
+            context=context,
+        ).items():
+            argv[-1:-1] = ["--build-arg", f"{name}={value}"]
         proc = run_docker(argv)
         if proc.returncode != 0:
             raise GatewayError(f"gateway image build failed: {proc.stderr.strip()}")

bot_bottle/backend/docker/orchestrator.py

@@ -131,6 +131,11 @@ class DockerOrchestrator(Orchestrator):
                 str(self._repo_root)]
         if os.environ.get("BOT_BOTTLE_NO_CACHE"):
             argv.insert(2, "--no-cache")
+        for name, value in resources.image_build_args(
+            self._dockerfile,
+            context=self._repo_root,
+        ).items():
+            argv[-1:-1] = ["--build-arg", f"{name}={value}"]
         proc = run_docker(argv)
         if proc.returncode != 0:
             raise GatewayError(

bot_bottle/backend/docker/util.py

@@ -10,6 +10,7 @@ import shutil
 import subprocess
 from typing import Iterator
 
+from ... import resources
 from ...log import die, info
 from ...util import slugify as _slugify
 
@@ -145,7 +146,12 @@ def build_image(
         args.append("--no-cache")
     if dockerfile:
         args.extend(["-f", dockerfile])
-    for name, value in (build_args or {}).items():
+    effective_build_args = resources.image_build_args(
+        dockerfile,
+        context=context,
+    ) if dockerfile else {}
+    effective_build_args.update(build_args or {})
+    for name, value in effective_build_args.items():
         args.extend(["--build-arg", f"{name}={value}"])
     args.append(context)
     subprocess.run(args, check=True)