Support for Kubernetes Jobs

doc/configuration.rst

@@ -382,6 +382,29 @@ release
   "cdh4".
 
 
+[k8s]
+-------
+
+Parameters controlling Kubernetes Job Tasks
+
+auth_method
+  Authorization method to access the cluster.
+  Options are "kubeconfig_" or "service-account_"
+
+kubeconfig_path
+  Path to kubeconfig file, for cluster authentication.
+  It defaults to ``~/.kube/config``, which is the default location when
+  using minikube_.
+  When auth_method is "service-account" this property is ignored.
+
+max_retrials
+  Maximum number of retrials in case of job failure.
+
+.. _service-account: http://kubernetes.io/docs/user-guide/kubeconfig-file
+.. _kubeconfig: http://kubernetes.io/docs/user-guide/service-accounts
+.. _minikube: http://kubernetes.io/docs/getting-started-guides/minikube
+
+
 [mysql]
 -------
 

examples/kubernetes_job.py

@@ -0,0 +1,65 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2015 Outlier Bio, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""
+Example Kubernetes Job Task.
+
+Requires:
+
+- pykube: ``pip install pykube``
+- A local minikube custer up and running: http://kubernetes.io/docs/getting-started-guides/minikube/
+
+**WARNING**: For Python versions < 3.5 the kubeconfig file must point to a Kubernetes API
+hostname, and NOT to an IP address.
+
+You can run this code example like this:
+
+    .. code:: console
+        $ luigi --module examples.kubernetes_job PerlPi --local-scheduler
+
+Running this code will create a pi-luigi-uuid kubernetes job within the cluster
+pointed to by the default context in "~/.kube/config".
+
+If running within a kubernetes cluster, set auth_method = "service-account" to
+access the local cluster.
+"""
+
+# import os
+# import luigi
+from luigi.contrib.k8s_job import KubernetesJobTask
+
+
+class PerlPi(KubernetesJobTask):
+
+    name = "pi"
+    max_retrials = 3
+    spec_schema = {
+        "containers": [{
+            "name": "pi",
+            "image": "perl",
+            "command": ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
+        }]
+    }
+
+    # defining the two functions below allows for dependency checking,
+    # but isn't a requirement
+    # def signal_complete(self):
+    #     with self.output().open('w') as output:
+    #         output.write('')
+    #
+    # def output(self):
+    #     target = os.path.join("/tmp", "PerlPi")
+    #     return luigi.LocalTarget(target)

luigi/contrib/k8s_job.py

@@ -0,0 +1,231 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2015 Outlier Bio, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+
+"""
+Kubernetes Job wrapper for Luigi.
+
+From the Kubernetes website:
+
+    Kubernetes is an open-source system for automating deployment, scaling,
+    and management of containerized applications.
+
+For more information about Kubernetes Jobs: http://kubernetes.io/docs/user-guide/jobs/
+
+Requires:
+
+- pykube: ``pip install pykube``
+
+Written and maintained by Marco Capuccini (@mcapuccini).
+"""
+
+import luigi
+from luigi import configuration
+import logging
+import uuid
+import time
+
+logger = logging.getLogger('luigi-interface')
+
+try:
+    from pykube.config import KubeConfig
+    from pykube.http import HTTPClient
+    from pykube.objects import Job
+except ImportError:
+    logger.warning('pykube is not installed. KubernetesJobTask requires pykube.')
+
+
+class KubernetesJobTask(luigi.Task):
+
+    __POLL_TIME = 5  # see __track_job
+
+    def _init_k8s(self):
+        self.__logger = logger
+        self.__logger.debug("Kubernetes auth method: " + self.auth_method)
+        if(self.auth_method == "kubeconfig"):
+            self.__kube_api = HTTPClient(KubeConfig.from_file(self.kubeconfig_path))
+        elif(self.auth_method == "service-account"):
+            self.__kube_api = HTTPClient(KubeConfig.from_service_account())
+        else:
+            raise ValueError("Illegal auth_method")
+        self.job_uuid = str(uuid.uuid4().hex)
+        self.uu_name = self.name + "-luigi-" + self.job_uuid
+        if ("restartPolicy" not in self.spec_schema):
+            self.spec_schema["restartPolicy"] = "Never"
+
+    @property
+    def auth_method(self):
+        """
+        This can be set to ``kubeconfig`` or ``service-account``.
+        It defaults to ``kubeconfig``.
+
+        For more details, please refer to:
+
+        - kubeconfig: http://kubernetes.io/docs/user-guide/kubeconfig-file
+        - service-account: http://kubernetes.io/docs/user-guide/service-accounts
+        """
+        return configuration.get_config().get("k8s", "auth_method", "kubeconfig")
+
+    @property
+    def kubeconfig_path(self):
+        """
+        Path to kubeconfig file used for cluster authentication.
+        It defaults to "~/.kube/config", which is the default location
+        when using minikube (http://kubernetes.io/docs/getting-started-guides/minikube).
+        When auth_method is ``service-account`` this property is ignored.
+
+        **WARNING**: For Python versions < 3.5 kubeconfig must point to a Kubernetes API
+        hostname, and NOT to an IP address.
+
+        For more details, please refer to:
+        http://kubernetes.io/docs/user-guide/kubeconfig-file
+        """
+        return configuration.get_config().get("k8s", "kubeconfig_path", "~/.kube/config")
+
+    @property
+    def name(self):
+        """
+        A name for this job. This task will automatically append a UUID to the
+        name before to submit to Kubernetes.
+        """
+        raise NotImplementedError("subclass must define name")
+
+    @property
+    def labels(self):
+        """
+        Return custom labels for kubernetes job.
+        example::
+            ``{"run_dt": datetime.date.today().strftime('%F')}``
+        """
+        return {}
+
+    @property
+    def spec_schema(self):
+        """
+        Kubernetes Job spec schema in JSON format, example::
+        .. code-block:: javascript
+
+            {
+                "containers": [{
+                    "name": "pi",
+                    "image": "perl",
+                    "command": ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
+                }],
+                "restartPolicy": "Never"
+            }
+
+        **restartPolicy**
+
+        - If restartPolicy is not defined, it will be set to "Never" by default.
+
+        - **Warning**: restartPolicy=OnFailure will bypass max_retrials, and restart
+        the container until success, with the risk of blocking the Luigi task.
+
+        For more informations please refer to:
+        http://kubernetes.io/docs/user-guide/pods/multi-container/#the-spec-schema
+        """
+        raise NotImplementedError("subclass must define spec_schema")
+
+    @property
+    def max_retrials(self):
+        """
+        Maximum number of retrials in case of failure.
+        """
+        return configuration.get_config().get("k8s", "max_retrials", 0)
+
+    def __track_job(self):
+        """Poll job status while active"""
+        while (self.__get_job_status() == "running"):
+            self.__logger.debug("Kubernetes job " + self.uu_name
+                                + " is still running")
+            time.sleep(self.__POLL_TIME)
+        if(self.__get_job_status() == "succeeded"):
+            self.__logger.info("Kubernetes job " + self.uu_name + " succeeded")
+            # Use signal_complete to notify of job completion
+            self.signal_complete()
+        else:
+            raise RuntimeError("Kubernetes job " + self.uu_name + " failed")
+
+    def signal_complete(self):
+        """Signal job completion for scheduler and dependent tasks.
+
+         Touching a system file is an easy way to signal completion. example::
+         .. code-block:: python
+
+         with self.output().open('w') as output_file:
+             output_file.write('')
+        """
+        pass
+
+    def __get_job_status(self):
+        """Return the Kubernetes job status"""
+        # Look for the required job
+        jobs = Job.objects(self.__kube_api).filter(selector="luigi_task_id="
+                                                            + self.job_uuid)
+        # Raise an exception if no such job found
+        if len(jobs.response["items"]) == 0:
+            raise RuntimeError("Kubernetes job " + self.uu_name + " not found")
+        # Figure out status and return it
+        job = Job(self.__kube_api, jobs.response["items"][0])
+        if ("succeeded" in job.obj["status"] and job.obj["status"]["succeeded"] > 0):
+            job.scale(replicas=0)  # Downscale the job, but keep it for logging
+            return "succeeded"
+        if ("failed" in job.obj["status"]):
+            failed_cnt = job.obj["status"]["failed"]
+            self.__logger.debug("Kubernetes job " + self.uu_name
+                                + " status.failed: " + str(failed_cnt))
+            if (failed_cnt > self.max_retrials):
+                job.scale(replicas=0)  # avoid more retrials
+                return "failed"
+        return "running"
+
+    def run(self):
+        self._init_k8s()
+        # Submit the Job
+        self.__logger.info("Submitting Kubernetes Job: " + self.uu_name)
+        job_json = {
+            "apiVersion": "batch/v1",
+            "kind": "Job",
+            "metadata": {
+                "name": self.uu_name,
+                "labels": {
+                    "spawned_by": "luigi",
+                    "luigi_task_id": self.job_uuid
+                }
+            },
+            "spec": {
+                "template": {
+                    "metadata": {
+                        "name": self.uu_name
+                    },
+                    "spec": self.spec_schema
+                }
+            }
+        }
+        job_json['metadata']['labels'].update(self.labels)
+        job = Job(self.__kube_api, job_json)
+        job.create()
+        # Track the Job (wait while active)
+        self.__logger.info("Start tracking Kubernetes Job: " + self.uu_name)
+        self.__track_job()
+
+    def output(self):
+        """An output target is necessary for checking job completion unless
+        alternative complete method is defined.
+         example::
+        ``return luigi.LocalTarget(os.path.join('/tmp', 'example'))``"""
+        pass