build: pin and verify image inputs

bot_bottle/backend/docker/util.py

@@ -119,7 +119,13 @@ def docker_cp(src: str, dest: str) -> None:
             f"{(result.stderr or '').strip() or '<no stderr>'}")
 
 
-def build_image(ref: str, context: str, *, dockerfile: str = "") -> None:
+def build_image(
+    ref: str,
+    context: str,
+    *,
+    dockerfile: str = "",
+    build_args: dict[str, str] | None = None,
+) -> None:
     """Invokes `docker build` every call. Layer cache makes no-change
     rebuilds cheap; running every time means Dockerfile edits land
     without manual `docker rmi`.
@@ -139,10 +145,26 @@ def build_image(ref: str, context: str, *, dockerfile: str = "") -> None:
         args.append("--no-cache")
     if dockerfile:
         args.extend(["-f", dockerfile])
+    for name, value in (build_args or {}).items():
+        args.extend(["--build-arg", f"{name}={value}"])
     args.append(context)
     subprocess.run(args, check=True)
 
 
+def image_id(ref: str) -> str:
+    """Return the exact content-addressed ID for a local image.
+
+    This is used when one locally built image is another Dockerfile's base:
+    passing the ID prevents a mutable tag from being resolved between builds.
+    """
+    result = run_docker(["docker", "image", "inspect", "--format", "{{.Id}}", ref])
+    image = result.stdout.strip()
+    if result.returncode != 0 or not image.startswith("sha256:"):
+        detail = (result.stderr or result.stdout or "").strip()
+        die(f"could not resolve exact image ID for {ref!r}: {detail or '<no detail>'}")
+    return image
+
+
 def verify_agent_image(image: str, argv: tuple[str, ...]) -> None:
     """Run `argv` inside a throwaway container of a freshly built agent
     image and die loudly if it fails, instead of shipping an image

bot_bottle/backend/firecracker/infra_artifact.py

@@ -49,9 +49,9 @@ _ARTIFACT_FORMAT = "1"
 # from its own generic package; the Dockerfiles baked into each differ (only the
 # orchestrator rootfs carries buildah), so the versions are hashed separately.
 ROLES = ("orchestrator", "gateway")
-_DOCKERFILES = {
+_BUILD_INPUTS = {
     "orchestrator": ("Dockerfile.orchestrator", "Dockerfile.orchestrator.fc"),
-    "gateway": ("Dockerfile.gateway",),
+    "gateway": ("Dockerfile.gateway", "requirements.gateway.lock"),
 }
 
 _DEFAULT_BASE = "https://gitea.dideric.is"
@@ -101,7 +101,7 @@ def infra_artifact_version(
         h.update(str(path.relative_to(repo_root)).encode())
         h.update(b"\0")
         h.update(path.read_bytes())
-    for name in _DOCKERFILES[role]:
+    for name in _BUILD_INPUTS[role]:
         h.update(name.encode())
         h.update(b"\0")
         h.update((repo_root / name).read_bytes())

bot_bottle/backend/firecracker/infra_vm.py

@@ -133,10 +133,15 @@ def build_infra_images_with_docker() -> None:
     root = str(resources.build_root())
     docker_mod.build_image(
         _ORCHESTRATOR_IMAGE, root, dockerfile="Dockerfile.orchestrator")
+    orchestrator_id = docker_mod.image_id(_ORCHESTRATOR_IMAGE)
     docker_mod.build_image(
         _GATEWAY_IMAGE, root, dockerfile="Dockerfile.gateway")
     docker_mod.build_image(
-        _ORCHESTRATOR_FC_IMAGE, root, dockerfile="Dockerfile.orchestrator.fc")
+        _ORCHESTRATOR_FC_IMAGE,
+        root,
+        dockerfile="Dockerfile.orchestrator.fc",
+        build_args={"ORCHESTRATOR_BASE_IMAGE": orchestrator_id},
+    )
 
 
 def build_rootfs_dir(role: str) -> Path: