Docker Utils: Expose the build logs (#12376)

bblommers · web-flow · commit c4e88ef067a2 · 2025-03-14T11:28:15.000-01:00
diff --git a/localstack-core/localstack/utils/container_utils/container_client.py b/localstack-core/localstack/utils/container_utils/container_client.py
@@ -701,13 +701,14 @@ def build_image(
         image_name: str,
         context_path: str = None,
         platform: Optional[DockerPlatform] = None,
-    ) -> None:
+    ) -> str:
         """Builds an image from the given Dockerfile
 
         :param dockerfile_path: Path to Dockerfile, or a directory that contains a Dockerfile
         :param image_name: Name of the image to be built
         :param context_path: Path for build context (defaults to dirname of Dockerfile)
         :param platform: Target platform for build (defaults to platform of Docker host)
+        :return: Build logs as a string.
         """
 
     @abstractmethod
diff --git a/localstack-core/localstack/utils/container_utils/docker_cmd_client.py b/localstack-core/localstack/utils/container_utils/docker_cmd_client.py
@@ -412,7 +412,7 @@ def build_image(
         cmd += [context_path]
         LOG.debug("Building Docker image: %s", cmd)
         try:
-            run(cmd)
+            return run(cmd)
         except subprocess.CalledProcessError as e:
             raise ContainerException(
                 f"Docker build process returned with error code {e.returncode}", e.stdout, e.stderr
diff --git a/localstack-core/localstack/utils/container_utils/docker_sdk_client.py b/localstack-core/localstack/utils/container_utils/docker_sdk_client.py
@@ -380,13 +380,23 @@ def build_image(
             dockerfile_path = Util.resolve_dockerfile_path(dockerfile_path)
             context_path = context_path or os.path.dirname(dockerfile_path)
             LOG.debug("Building Docker image %s from %s", image_name, dockerfile_path)
-            self.client().images.build(
+            _, logs_iterator = self.client().images.build(
                 path=context_path,
                 dockerfile=dockerfile_path,
                 tag=image_name,
                 rm=True,
                 platform=platform,
             )
+            # logs_iterator is a stream of dicts. Example content:
+            # {'stream': 'Step 1/4 : FROM alpine'}
+            # ... other build steps
+            # {'aux': {'ID': 'sha256:4dcf90e87fb963e898f9c7a0451a40e36f8e7137454c65ae4561277081747825'}}
+            # {'stream': 'Successfully tagged img-5201f3e1:latest\n'}
+            output = ""
+            for log in logs_iterator:
+                if isinstance(log, dict) and ("stream" in log or "error" in log):
+                    output += log.get("stream") or log["error"]
+            return output
         except APIError as e:
             raise ContainerException("Unable to build Docker image") from e
 
diff --git a/tests/integration/docker_utils/test_docker.py b/tests/integration/docker_utils/test_docker.py
@@ -1240,7 +1240,15 @@ def test_build_image(
         dockerfile_ref = str(dockerfile_dir) if dockerfile_as_dir else dockerfile_path
 
         image_name = f"img-{short_uid()}"
-        docker_client.build_image(dockerfile_path=dockerfile_ref, image_name=image_name, **kwargs)
+        build_logs = docker_client.build_image(
+            dockerfile_path=dockerfile_ref, image_name=image_name, **kwargs
+        )
+        # The exact log files are very different between the CMD and SDK
+        # We just run some smoke tests
+        assert build_logs
+        assert isinstance(build_logs, str)
+        assert "ADD" in build_logs
+
         cleanups.append(lambda: docker_client.remove_image(image_name, force=True))
 
         assert image_name in docker_client.get_docker_image_names()
