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Merge pull request apache-spark-on-k8s#399 from palantir/os/pod-template
[SPARK-24434][K8S] pod template files
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‎docs/running-on-kubernetes.md‎

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@@ -185,6 +185,21 @@ To use a secret through an environment variable use the following options to the
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--conf spark.kubernetes.executor.secretKeyRef.ENV_NAME=name:key
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```
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## Pod Template
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Kubernetes allows defining pods from [template files](https://kubernetes.io/docs/concepts/workloads/pods/pod-overview/#pod-templates).
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Spark users can similarly use template files to define the driver or executor pod configurations that Spark configurations do not support.
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To do so, specify the spark properties `spark.kubernetes.driver.podTemplateFile` and `spark.kubernetes.executor.podTemplateFile`
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to point to local files accessible to the `spark-submit` process. To allow the driver pod access the executor pod template
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file, the file will be automatically mounted onto a volume in the driver pod when it's created.
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It is important to note that Spark is opinionated about certain pod configurations so there are values in the
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pod template that will always be overwritten by Spark. Therefore, users of this feature should note that specifying
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the pod template file only lets Spark start with a template pod instead of an empty pod during the pod-building process.
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For details, see the [full list](#pod-template-properties) of pod template values that will be overwritten by spark.
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Pod template files can also define multiple containers. In such cases, Spark will always assume that the first container in
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the list will be the driver or executor container.
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## Introspection and Debugging
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These are the different ways in which you can investigate a running/completed Spark application, monitor progress, and
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This sets the major Python version of the docker image used to run the driver and executor containers. Can either be 2 or 3.
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</td>
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</tr>
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<tr>
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<td><code>spark.kubernetes.driver.podTemplateFile</code></td>
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<td>(none)</td>
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<td>
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Specify the local file that contains the driver [pod template](#pod-template). For example
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<code>spark.kubernetes.driver.podTemplateFile=/path/to/driver-pod-template.yaml`</code>
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</td>
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</tr>
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<tr>
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<td><code>spark.kubernetes.executor.podTemplateFile</code></td>
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<td>(none)</td>
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<td>
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Specify the local file that contains the executor [pod template](#pod-template). For example
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<code>spark.kubernetes.executor.podTemplateFile=/path/to/executor-pod-template.yaml`</code>
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</td>
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</tr>
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</table>
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#### Pod template properties
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See the below table for the full list of pod specifications that will be overwritten by spark.
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### Pod Metadata
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<table class="table">
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<tr><th>Pod metadata key</th><th>Modified value</th><th>Description</th></tr>
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<tr>
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<td>name</td>
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<td>Value of <code>spark.kubernetes.driver.pod.name</code></td>
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<td>
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The driver pod name will be overwritten with either the configured or default value of
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<code>spark.kubernetes.driver.pod.name</code>. The executor pod names will be unaffected.
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</td>
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</tr>
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<tr>
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<td>namespace</td>
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<td>Value of <code>spark.kubernetes.namespace</code></td>
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<td>
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Spark makes strong assumptions about the driver and executor namespaces. Both driver and executor namespaces will
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be replaced by either the configured or default spark conf value.
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</td>
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</tr>
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<tr>
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<td>labels</td>
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<td>Adds the labels from <code>spark.kubernetes.{driver,executor}.label.*</code></td>
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<td>
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Spark will add additional labels specified by the spark configuration.
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</td>
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</tr>
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<tr>
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<td>annotations</td>
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<td>Adds the annotations from <code>spark.kubernetes.{driver,executor}.annotation.*</code></td>
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<td>
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Spark will add additional labels specified by the spark configuration.
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</td>
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</tr>
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</table>
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### Pod Spec
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<table class="table">
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<tr><th>Pod spec key</th><th>Modified value</th><th>Description</th></tr>
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<tr>
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<td>imagePullSecrets</td>
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<td>Adds image pull secrets from <code>spark.kubernetes.container.image.pullSecrets</code></td>
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<td>
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Additional pull secrets will be added from the spark configuration to both executor pods.
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</td>
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</tr>
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<tr>
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<td>nodeSelector</td>
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<td>Adds node selectors from <code>spark.kubernetes.node.selector.*</code></td>
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<td>
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Additional node selectors will be added from the spark configuration to both executor pods.
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</td>
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</tr>
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<tr>
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<td>restartPolicy</td>
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<td><code>"never"</code></td>
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<td>
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Spark assumes that both drivers and executors never restart.
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</td>
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</tr>
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<tr>
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<td>serviceAccount</td>
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<td>Value of <code>spark.kubernetes.authenticate.driver.serviceAccountName</code></td>
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<td>
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Spark will override <code>serviceAccount</code> with the value of the spark configuration for only
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driver pods, and only if the spark configuration is specified. Executor pods will remain unaffected.
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</td>
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</tr>
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<tr>
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<td>serviceAccountName</td>
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<td>Value of <code>spark.kubernetes.authenticate.driver.serviceAccountName</code></td>
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<td>
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Spark will override <code>serviceAccountName</code> with the value of the spark configuration for only
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driver pods, and only if the spark configuration is specified. Executor pods will remain unaffected.
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</td>
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</tr>
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<tr>
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<td>volumes</td>
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<td>Adds volumes from <code>spark.kubernetes.{driver,executor}.volumes.[VolumeType].[VolumeName].mount.path</code></td>
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<td>
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Spark will add volumes as specified by the spark conf, as well as additional volumes necessary for passing
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spark conf and pod template files.
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</td>
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</tr>
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</table>
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### Container spec
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The following affect the driver and executor containers. All other containers in the pod spec will be unaffected.
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<table class="table">
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<tr><th>Container spec key</th><th>Modified value</th><th>Description</th></tr>
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<tr>
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<td>env</td>
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<td>Adds env variables from <code>spark.kubernetes.driverEnv.[EnvironmentVariableName]</code></td>
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<td>
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Spark will add driver env variables from <code>spark.kubernetes.driverEnv.[EnvironmentVariableName]</code>, and
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executor env variables from <code>spark.executorEnv.[EnvironmentVariableName]</code>.
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</td>
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</tr>
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<tr>
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<td>image</td>
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<td>Value of <code>spark.kubernetes.{driver,executor}.container.image</code></td>
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<td>
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The image will be defined by the spark configurations.
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</td>
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</tr>
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<tr>
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<td>imagePullPolicy</td>
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<td>Value of <code>spark.kubernetes.container.image.pullPolicy</code></td>
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<td>
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Spark will override the pull policy for both driver and executors.
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</td>
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</tr>
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<tr>
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<td>name</td>
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<td>See description.</code></td>
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<td>
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The container name will be assigned by spark ("spark-kubernetes-driver" for the driver container, and
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"executor" for each executor container) if not defined by the pod template. If the container is defined by the
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template, the template's name will be used.
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</td>
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</tr>
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<tr>
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<td>resources</td>
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<td>See description</td>
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<td>
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The cpu limits are set by <code>spark.kubernetes.{driver,executor}.limit.cores</code>. The cpu is set by
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<code>spark.{driver,executor}.cores</code>. The memory request and limit are set by summing the values of
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<code>spark.{driver,executor}.memory</code> and <code>spark.{driver,executor}.memoryOverhead</code>.
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</td>
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</tr>
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<tr>
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<td>volumeMounts</td>
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<td>Add volumes from <code>spark.kubernetes.driver.volumes.[VolumeType].[VolumeName].mount.{path,readOnly}</code></td>
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<td>
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Spark will add volumes as specified by the spark conf, as well as additional volumes necessary for passing
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spark conf and pod template files.
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</td>
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</tr>
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</table>

‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala‎

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"Ensure that major Python version is either Python2 or Python3")
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.createWithDefault("2")
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val KUBERNETES_DRIVER_PODTEMPLATE_FILE =
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ConfigBuilder("spark.kubernetes.driver.podTemplateFile")
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.doc("File containing a template pod spec for the driver")
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.stringConf
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.createOptional
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val KUBERNETES_EXECUTOR_PODTEMPLATE_FILE =
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ConfigBuilder("spark.kubernetes.executor.podTemplateFile")
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.doc("File containing a template pod spec for executors")
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.stringConf
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.createOptional
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val KUBERNETES_AUTH_SUBMISSION_CONF_PREFIX =
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"spark.kubernetes.authenticate.submission"
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‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Constants.scala‎

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val ENV_PYSPARK_ARGS = "PYSPARK_APP_ARGS"
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val ENV_PYSPARK_MAJOR_PYTHON_VERSION = "PYSPARK_MAJOR_PYTHON_VERSION"
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// Pod spec templates
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val EXECUTOR_POD_SPEC_TEMPLATE_FILE_NAME = "pod-spec-template.yml"
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val EXECUTOR_POD_SPEC_TEMPLATE_MOUNTHPATH = "/opt/spark/pod-template"
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val POD_TEMPLATE_VOLUME = "podspec-volume"
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val POD_TEMPLATE_CONFIGMAP = "podspec-configmap"
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val POD_TEMPLATE_KEY = "podspec-configmap-key"
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// Miscellaneous
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val KUBERNETES_MASTER_INTERNAL_URL = "https://kubernetes.default.svc"
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val DRIVER_CONTAINER_NAME = "spark-kubernetes-driver"
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val DEFAULT_DRIVER_CONTAINER_NAME = "spark-kubernetes-driver"
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val DEFAULT_EXECUTOR_CONTAINER_NAME = "spark-kubernetes-executor"
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val MEMORY_OVERHEAD_MIN_MIB = 384L
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}

‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/KubernetesDriverSpec.scala‎

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pod: SparkPod,
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driverKubernetesResources: Seq[HasMetadata],
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systemProperties: Map[String, String])
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private[spark] object KubernetesDriverSpec {
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def initialSpec(initialProps: Map[String, String]): KubernetesDriverSpec = KubernetesDriverSpec(
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SparkPod.initialPod(),
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Seq.empty,
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initialProps)
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}

‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/KubernetesUtils.scala‎

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import java.io.File
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import org.apache.spark.SparkConf
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import io.fabric8.kubernetes.api.model.{ContainerBuilder, PodBuilder}
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import io.fabric8.kubernetes.client.KubernetesClient
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import scala.collection.JavaConverters._
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import org.apache.spark.{SparkConf, SparkException}
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import org.apache.spark.internal.Logging
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import org.apache.spark.util.Utils
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private[spark] object KubernetesUtils {
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private[spark] object KubernetesUtils extends Logging {
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/**
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* Extract and parse Spark configuration properties with a given name prefix and
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}
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}
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def loadPodFromTemplate(
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kubernetesClient: KubernetesClient,
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templateFile: File): SparkPod = {
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try {
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val pod = kubernetesClient.pods().load(templateFile).get()
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pod.getSpec.getContainers.asScala.toList match {
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case first :: rest => SparkPod(
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new PodBuilder(pod)
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.editSpec()
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.withContainers(rest.asJava)
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.endSpec()
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.build(),
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first)
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case Nil => SparkPod(pod, new ContainerBuilder().build())
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}
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} catch {
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case e: Exception =>
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logError(
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s"Encountered exception while attempting to load initial pod spec from file", e)
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throw new SparkException("Could not load pod from template file.", e)
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}
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}
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def parseMasterUrl(url: String): String = url.substring("k8s://".length)
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}

‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/features/BasicDriverFeatureStep.scala‎

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)
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val driverUIPort = SparkUI.getUIPort(conf.sparkConf)
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val driverContainer = new ContainerBuilder(pod.container)
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.withName(DRIVER_CONTAINER_NAME)
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.withName(Option(pod.container.getName).getOrElse(DEFAULT_DRIVER_CONTAINER_NAME))
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.withImage(driverContainerImage)
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.withImagePullPolicy(conf.imagePullPolicy())
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.addNewPort()
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.withNewFieldRef("v1", "status.podIP")
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.build())
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.endEnv()
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.withNewResources()
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.editOrNewResources()
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.addToRequests("cpu", driverCpuQuantity)
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.addToLimits(maybeCpuLimitQuantity.toMap.asJava)
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.addToRequests("memory", driverMemoryQuantity)
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.addToLabels(conf.roleLabels.asJava)
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.addToAnnotations(conf.roleAnnotations.asJava)
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.endMetadata()
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.withNewSpec()
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.editOrNewSpec()
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.withRestartPolicy("Never")
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.withNodeSelector(conf.nodeSelector().asJava)
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.addToNodeSelector(conf.nodeSelector().asJava)
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.addToImagePullSecrets(conf.imagePullSecrets(): _*)
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.endSpec()
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.build()

‎resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/features/BasicExecutorFeatureStep.scala‎

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}
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val executorContainer = new ContainerBuilder(pod.container)
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.withName("executor")
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.withName(Option(pod.container.getName).getOrElse(DEFAULT_EXECUTOR_CONTAINER_NAME))
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.withImage(executorContainerImage)
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.withImagePullPolicy(kubernetesConf.imagePullPolicy())
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.withNewResources()
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.editOrNewResources()
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.addToRequests("memory", executorMemoryQuantity)
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.addToLimits("memory", executorMemoryQuantity)
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.addToRequests("cpu", executorCpuQuantity)
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val executorPod = new PodBuilder(pod.pod)
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.editOrNewMetadata()
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.withName(name)
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.withLabels(kubernetesConf.roleLabels.asJava)
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.withAnnotations(kubernetesConf.roleAnnotations.asJava)
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.addToLabels(kubernetesConf.roleLabels.asJava)
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.addToAnnotations(kubernetesConf.roleAnnotations.asJava)
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.addToOwnerReferences(ownerReference.toSeq: _*)
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.endMetadata()
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.editOrNewSpec()
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.withHostname(hostname)
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.withRestartPolicy("Never")
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.withNodeSelector(kubernetesConf.nodeSelector().asJava)
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.addToNodeSelector(kubernetesConf.nodeSelector().asJava)
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.addToImagePullSecrets(kubernetesConf.imagePullSecrets(): _*)
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.endSpec()
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.build()

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