Implement container resource updates

zoe_master/backends/base.py

@@ -57,3 +57,7 @@ class BaseBackend:
     def preload_image(self, image_name: str) -> None:
         """Make a service image available."""
         raise NotImplementedError
+
+    def update_service(self, service, cores=None, memory=None):
+        """Update a service reservation."""
+        raise NotImplementedError

zoe_master/backends/docker/api_client.py

@@ -318,3 +318,23 @@ class DockerClient:
         except docker.errors.APIError as e:
             log.error('Cannot download image {}: {}'.format(image_name, e))
             raise ZoeException('Cannot download image {}: {}'.format(image_name, e))
+
+    def update(self, docker_id, cpu_quota=None, mem_reservation=None, mem_limit=None):
+        """Update the resource reservation for a container."""
+        kwargs = {}
+        if cpu_quota is not None:
+            kwargs['cpu_quota'] = cpu_quota
+        if mem_reservation is not None:
+            kwargs['mem_reservation'] = mem_reservation
+        if mem_limit is not None:
+            kwargs['mem_limit'] = mem_limit
+
+        try:
+            cont = self.cli.containers.get(docker_id)
+        except (docker.errors.NotFound, docker.errors.APIError):
+            return
+
+        try:
+            cont.update(**kwargs)
+        except docker.errors.APIError:
+            pass

zoe_master/backends/docker/backend.py

@@ -187,3 +187,18 @@ class DockerEngineBackend(zoe_master.backends.base.BaseBackend):
             log.debug('Image {} pre-loaded on host {} in {:.2f}s'.format(image_name, host_conf.name, time.time() - time_start))
         if not one_success:
             raise ZoeException('Cannot pull image {}'.format(image_name))
+
+    def update_service(self, service, cores=None, memory=None):
+        """Update a service reservation."""
+        conf = self._get_config(service.backend_host)
+        engine = DockerClient(conf)
+        if service.backend_id is not None:
+            info = engine.info()
+            if cores is not None and cores > info['NCPU']:
+                cores = info['NCPU']
+            if memory is not None and memory > info['MemTotal']:
+                memory = info['MemTotal']
+            cpu_quota = cores * 1000000
+            engine.update(service.backend_id, cpu_quota=cpu_quota, mem_reservation=memory)
+        else:
+            log.error('Cannot terminate service {}, since it has not backend ID'.format(service.name))

zoe_master/backends/kubernetes/backend.py

@@ -78,3 +78,7 @@ class KubernetesBackend(zoe_master.backends.base.BaseBackend):
     def preload_image(self, image_name: str) -> None:
         """Make a service image available."""
         raise NotImplementedError
+
+    def update_service(self, service, cores=None, memory=None):
+        """Update a service reservation."""
+        log.error('Reservation update not implemented in the Swarm back-end')

zoe_master/backends/swarm/backend.py

@@ -85,3 +85,7 @@ class SwarmBackend(zoe_master.backends.base.BaseBackend):
     def preload_image(self, image_name: str) -> None:
         """Make a service image available."""
         raise NotImplementedError
+
+    def update_service(self, service, cores=None, memory=None):
+        """Update a service reservation."""
+        log.error('Reservation update not implemented in the Swarm back-end')