Bug:  invalid `spark.kubernetes.executor.podNamePrefix` causes app to hang
Status: Resolved | Priority: Major | Resolution: Fixed
Created: 20/May/21 14:02
Affects Version/s: 3.2.0


{code:java}
21/05/20 21:41:21 WARN ExecutorPodsSnapshotsStoreImpl: Exception when notifying snapshot subscriber.
io.fabric8.kubernetes.client.KubernetesClientException: Failure executing: POST at: https://kubernetes.docker.internal:6443/api/v1/namespaces/default/pods. Message: Pod "spark_exec-exec-688" is invalid: [metadata.name: Invalid value: "spark_exec-exec-688": a DNS-1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'), spec.hostname: Invalid value: "spark_exec-exec-688": a DNS-1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')]. Received status: Status(apiVersion=v1, code=422, details=StatusDetails(causes=[StatusCause(field=metadata.name, message=Invalid value: "spark_exec-exec-688": a DNS-1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'), reason=FieldValueInvalid, additionalProperties={}), StatusCause(field=spec.hostname, message=Invalid value: "spark_exec-exec-688": a DNS-1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?'), reason=FieldValueInvalid, additionalProperties={})], group=null, kind=Pod, name=spark_exec-exec-688, retryAfterSeconds=null, uid=null, additionalProperties={}), kind=Status, message=Pod "spark_exec-exec-688" is invalid: [metadata.name: Invalid value: "spark_exec-exec-688": a DNS-1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'), spec.hostname: Invalid value: "spark_exec-exec-688": a DNS-1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')], metadata=ListMeta(_continue=null, remainingItemCount=null, resourceVersion=null, selfLink=null, additionalProperties={}), reason=Invalid, status=Failure, additionalProperties={}).
	at io.fabric8.kubernetes.client.dsl.base.OperationSupport.requestFailure(OperationSupport.java:583)
	at io.fabric8.kubernetes.client.dsl.base.OperationSupport.assertResponseCode(OperationSupport.java:522)
	at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:487)
	at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:448)
	at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleCreate(OperationSupport.java:263)
	at io.fabric8.kubernetes.client.dsl.base.BaseOperation.handleCreate(BaseOperation.java:870)
	at io.fabric8.kubernetes.client.dsl.base.BaseOperation.create(BaseOperation.java:365)
	at io.fabric8.kubernetes.client.dsl.base.BaseOperation.create(BaseOperation.java:86)
{code}

When `spark.kubernetes.executor.podNamePrefix` contains invalid characters, the driver will continuously fail to request executors from k8s master, which causes the app to hang with the above message.