DRU-774 -- Lead each template image tag with its label

src/providers/docker/images.py

@@ -1,5 +1,6 @@
 import hashlib
 import io
+import re
 import tarfile
 
 from core.settings import get_settings
@@ -13,10 +14,15 @@ def derive_image_name(
     *,
     base_image: str,
     setup_script: str,
+    label: str,
     repository: str = "drukbox-template",
 ) -> str:
     identity = base_image.encode("utf-8") + b"\0" + setup_script.encode("utf-8")
     digest = hashlib.sha256(identity).hexdigest()[:12]
+    # A tag holds at most 128 characters, and the digest needs 13 of them.
+    purpose = re.sub(r"[^a-z0-9]+", "-", label.lower())[:115].strip("-")
+    if purpose:
+        return f"{repository}:{purpose}-{digest}"
     return f"{repository}:{digest}"
 
 
@@ -42,6 +48,7 @@ async def build_derived_image(
     *,
     base_image: str,
     setup_script: str,
+    label: str,
 ) -> str:
     settings = get_settings()
     repository = "drukbox-template"
@@ -50,6 +57,7 @@ async def build_derived_image(
     image = derive_image_name(
         base_image=base_image,
         setup_script=setup_script,
+        label=label,
         repository=repository,
     )
     context_tar = create_build_context(base_image=base_image, setup_script=setup_script)

src/providers/docker/provider.py

@@ -158,6 +158,7 @@ async def build_template_image(
             self.api,
             base_image=base_image,
             setup_script=setup_script,
+            label=label,
         )
 
     async def delete_template_image(self, image: str) -> None:

src/providers/docker/tests/test_images.py

@@ -32,16 +32,35 @@ def test_create_build_context_contains_the_base_and_verbatim_script() -> None:
 
 
 def test_derive_image_name_is_deterministic_and_base_specific() -> None:
-    first = derive_image_name(base_image="sandbox:base", setup_script="apt-get update")
-    repeated = derive_image_name(base_image="sandbox:base", setup_script="apt-get update")
-    different_base = derive_image_name(base_image="sandbox:other", setup_script="apt-get update")
+    first = derive_image_name(base_image="sandbox:base", setup_script="apt-get update", label="")
+    repeated = derive_image_name(base_image="sandbox:base", setup_script="apt-get update", label="")
+    different_base = derive_image_name(
+        base_image="sandbox:other", setup_script="apt-get update", label=""
+    )
 
     assert first == repeated
     assert first.startswith("drukbox-template:")
     assert len(first.removeprefix("drukbox-template:")) == 12
     assert different_base != first
 
 
+@pytest.mark.parametrize(
+    ("label", "purpose"),
+    [
+        ("site-builder-build", "site-builder-build"),
+        ("Site_Builder / Build.sh", "site-builder-build-sh"),
+        ("x" * 200, "x" * 115),
+    ],
+)
+def test_derive_image_name_leads_the_tag_with_the_label(label: str, purpose: str) -> None:
+    image = derive_image_name(base_image="sandbox:base", setup_script="apt-get update", label=label)
+
+    tag = image.removeprefix("drukbox-template:")
+    assert tag.startswith(f"{purpose}-")
+    assert len(tag) == len(purpose) + 13
+    assert len(tag) <= 128
+
+
 async def test_build_derived_image_publishes_to_the_template_repository(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -52,9 +71,9 @@ async def test_build_derived_image_publishes_to_the_template_repository(
     docker = MagicMock(build_image=AsyncMock(), push_image=AsyncMock())
 
     image = await build_derived_image(
-        docker, base_image="sandbox:base", setup_script="apt-get update"
+        docker, base_image="sandbox:base", setup_script="apt-get update", label="node-tools"
     )
 
-    assert image.startswith("ghcr.io/acme/templates:")
+    assert image.startswith("ghcr.io/acme/templates:node-tools-")
     assert docker.build_image.await_args.args[0] == image
     docker.push_image.assert_awaited_once_with(image, username="bot", password="secret")

src/providers/docker/tests/test_provider.py

@@ -186,8 +186,7 @@ async def test_build_template_image_builds_and_returns_the_derived_tag():
         label="Node tools",
     )
 
-    assert image.startswith("drukbox-template:")
-    assert len(image.removeprefix("drukbox-template:")) == 12
+    assert image.startswith("drukbox-template:node-tools-")
     assert api.build_image.await_args.args[0] == image
 
 

src/providers/docker_sbx/provider.py

@@ -201,6 +201,7 @@ async def build_template_image(
             self.docker,
             base_image=base_image,
             setup_script=setup_script,
+            label=label,
         )
         # sbx keeps its own image store. The Docker image only carries the build.
         try:

src/providers/exe/provider.py

@@ -125,6 +125,7 @@ async def build_template_image(
             self.docker,
             base_image=base_image,
             setup_script=setup_script,
+            label=label,
         )
 
     async def delete_template_image(self, image: str) -> None:

src/providers/exe/tests/test_provider.py

@@ -189,8 +189,7 @@ async def test_build_template_image_builds_logs_in_and_pushes(
         label="Node tools",
     )
 
-    assert image.startswith("ghcr.io/acme/drukbox-templates:")
-    assert len(image.rpartition(":")[2]) == 12
+    assert image.startswith("ghcr.io/acme/drukbox-templates:node-tools-")
     assert docker.build_image.await_args.args[0] == image
     docker.push_image.assert_awaited_once_with(image, username="bot", password="secret")
 

src/templates/tests/conftest.py

@@ -71,7 +71,7 @@ async def build_template_image(
         self.built.append((base_image, setup_script, label))
         if self.build_error:
             raise self.build_error
-        return derive_image_name(base_image=base_image, setup_script=setup_script)
+        return derive_image_name(base_image=base_image, setup_script=setup_script, label=label)
 
     async def delete_template_image(self, image: str) -> None:
         self.deleted.append(image)

src/templates/tests/test_api.py

@@ -54,6 +54,7 @@ async def test_create_template_returns_building_then_becomes_available(client, t
     assert polled.json()["image"] == derive_image_name(
         base_image=template_provider.base_image_ref,
         setup_script=SETUP_SCRIPT,
+        label="Node tools",
     )
     assert "setup_script" not in polled.json()
     assert template_provider.built == [