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"""Launches PODs"""
import json
import math
import time
from datetime import datetime as dt
from typing import Optional, Tuple, Union
import pendulum
import tenacity
from kubernetes import client, watch
from kubernetes.client.models.v1_pod import V1Pod
from kubernetes.client.rest import ApiException
from kubernetes.stream import stream as kubernetes_stream
from pendulum import Date, DateTime, Duration, Time
from pendulum.parsing.exceptions import ParserError
from requests.exceptions import BaseHTTPError
from airflow.exceptions import AirflowException
from airflow.kubernetes.kube_client import get_kube_client
from airflow.kubernetes.pod_generator import PodDefaults
from airflow.settings import pod_mutation_hook
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.state import State
[docs]def should_retry_start_pod(exception: Exception):
"""Check if an Exception indicates a transient error and warrants retrying"""
if isinstance(exception, ApiException):
return exception.status == 409
return False
[docs]class PodStatus:
"""Status of the PODs"""
[docs] SUCCEEDED = 'succeeded'
[docs]class PodLauncher(LoggingMixin):
"""Launches PODS"""
def __init__(
self,
kube_client: client.CoreV1Api = None,
in_cluster: bool = True,
cluster_context: Optional[str] = None,
extract_xcom: bool = False,
):
"""
Creates the launcher.
:param kube_client: kubernetes client
:param in_cluster: whether we are in cluster
:param cluster_context: context of the cluster
:param extract_xcom: whether we should extract xcom
"""
super().__init__()
self._client = kube_client or get_kube_client(in_cluster=in_cluster, cluster_context=cluster_context)
self._watch = watch.Watch()
self.extract_xcom = extract_xcom
[docs] def run_pod_async(self, pod: V1Pod, **kwargs):
"""Runs POD asynchronously"""
pod_mutation_hook(pod)
sanitized_pod = self._client.api_client.sanitize_for_serialization(pod)
json_pod = json.dumps(sanitized_pod, indent=2)
self.log.debug('Pod Creation Request: \n%s', json_pod)
try:
resp = self._client.create_namespaced_pod(
body=sanitized_pod, namespace=pod.metadata.namespace, **kwargs
)
self.log.debug('Pod Creation Response: %s', resp)
except Exception as e:
self.log.exception('Exception when attempting to create Namespaced Pod: %s', json_pod)
raise e
return resp
[docs] def delete_pod(self, pod: V1Pod):
"""Deletes POD"""
try:
self._client.delete_namespaced_pod(
pod.metadata.name, pod.metadata.namespace, body=client.V1DeleteOptions()
)
except ApiException as e:
# If the pod is already deleted
if e.status != 404:
raise
@tenacity.retry(
stop=tenacity.stop_after_attempt(3),
wait=tenacity.wait_random_exponential(),
reraise=True,
retry=tenacity.retry_if_exception(should_retry_start_pod),
[docs] )
def start_pod(self, pod: V1Pod, startup_timeout: int = 120):
"""
Launches the pod synchronously and waits for completion.
:param pod:
:param startup_timeout: Timeout for startup of the pod (if pod is pending for too long, fails task)
:return:
"""
resp = self.run_pod_async(pod)
curr_time = dt.now()
if resp.status.start_time is None:
while self.pod_not_started(pod):
self.log.warning("Pod not yet started: %s", pod.metadata.name)
delta = dt.now() - curr_time
if delta.total_seconds() >= startup_timeout:
raise AirflowException("Pod took too long to start")
time.sleep(1)
[docs] def monitor_pod(self, pod: V1Pod, get_logs: bool) -> Tuple[State, V1Pod, Optional[str]]:
"""
Monitors a pod and returns the final state, pod and xcom result
:param pod: pod spec that will be monitored
:param get_logs: whether to read the logs locally
:return: Tuple[State, Optional[str]]
"""
if get_logs:
read_logs_since_sec = None
last_log_time = None
while True:
logs = self.read_pod_logs(pod, timestamps=True, since_seconds=read_logs_since_sec)
for line in logs:
timestamp, message = self.parse_log_line(line.decode('utf-8'))
self.log.info(message)
if timestamp:
last_log_time = timestamp
time.sleep(1)
if not self.base_container_is_running(pod):
break
self.log.warning('Pod %s log read interrupted', pod.metadata.name)
if last_log_time:
delta = pendulum.now() - last_log_time
# Prefer logs duplication rather than loss
read_logs_since_sec = math.ceil(delta.total_seconds())
result = None
if self.extract_xcom:
while self.base_container_is_running(pod):
self.log.info('Container %s has state %s', pod.metadata.name, State.RUNNING)
time.sleep(2)
result = self._extract_xcom(pod)
self.log.info(result)
result = json.loads(result)
while self.pod_is_running(pod):
self.log.info('Pod %s has state %s', pod.metadata.name, State.RUNNING)
time.sleep(2)
remote_pod = self.read_pod(pod)
return self._task_status(remote_pod), remote_pod, result
[docs] def parse_log_line(self, line: str) -> Tuple[Optional[Union[Date, Time, DateTime, Duration]], str]:
"""
Parse K8s log line and returns the final state
:param line: k8s log line
:type line: str
:return: timestamp and log message
:rtype: Tuple[str, str]
"""
split_at = line.find(' ')
if split_at == -1:
raise Exception(f'Log not in "{{timestamp}} {{log}}" format. Got: {line}')
timestamp = line[:split_at]
message = line[split_at + 1 :].rstrip()
try:
last_log_time = pendulum.parse(timestamp)
except ParserError:
self.log.error("Error parsing timestamp. Will continue execution but won't update timestamp")
return None, line
return last_log_time, message
def _task_status(self, event):
self.log.info('Event: %s had an event of type %s', event.metadata.name, event.status.phase)
status = self.process_status(event.metadata.name, event.status.phase)
return status
[docs] def pod_not_started(self, pod: V1Pod):
"""Tests if pod has not started"""
state = self._task_status(self.read_pod(pod))
return state == State.QUEUED
[docs] def pod_is_running(self, pod: V1Pod):
"""Tests if pod is running"""
state = self._task_status(self.read_pod(pod))
return state not in (State.SUCCESS, State.FAILED)
[docs] def base_container_is_running(self, pod: V1Pod):
"""Tests if base container is running"""
event = self.read_pod(pod)
status = next(iter(filter(lambda s: s.name == 'base', event.status.container_statuses)), None)
if not status:
return False
return status.state.running is not None
@tenacity.retry(stop=tenacity.stop_after_attempt(3), wait=tenacity.wait_exponential(), reraise=True)
[docs] def read_pod_logs(
self,
pod: V1Pod,
tail_lines: Optional[int] = None,
timestamps: bool = False,
since_seconds: Optional[int] = None,
):
"""Reads log from the POD"""
additional_kwargs = {}
if since_seconds:
additional_kwargs['since_seconds'] = since_seconds
if tail_lines:
additional_kwargs['tail_lines'] = tail_lines
try:
return self._client.read_namespaced_pod_log(
name=pod.metadata.name,
namespace=pod.metadata.namespace,
container='base',
follow=True,
timestamps=timestamps,
_preload_content=False,
**additional_kwargs,
)
except BaseHTTPError as e:
raise AirflowException(f'There was an error reading the kubernetes API: {e}')
@tenacity.retry(stop=tenacity.stop_after_attempt(3), wait=tenacity.wait_exponential(), reraise=True)
[docs] def read_pod_events(self, pod):
"""Reads events from the POD"""
try:
return self._client.list_namespaced_event(
namespace=pod.metadata.namespace, field_selector=f"involvedObject.name={pod.metadata.name}"
)
except BaseHTTPError as e:
raise AirflowException(f'There was an error reading the kubernetes API: {e}')
@tenacity.retry(stop=tenacity.stop_after_attempt(3), wait=tenacity.wait_exponential(), reraise=True)
[docs] def read_pod(self, pod: V1Pod):
"""Read POD information"""
try:
return self._client.read_namespaced_pod(pod.metadata.name, pod.metadata.namespace)
except BaseHTTPError as e:
raise AirflowException(f'There was an error reading the kubernetes API: {e}')
def _extract_xcom(self, pod: V1Pod):
resp = kubernetes_stream(
self._client.connect_get_namespaced_pod_exec,
pod.metadata.name,
pod.metadata.namespace,
container=PodDefaults.SIDECAR_CONTAINER_NAME,
command=['/bin/sh'],
stdin=True,
stdout=True,
stderr=True,
tty=False,
_preload_content=False,
)
try:
result = self._exec_pod_command(resp, f'cat {PodDefaults.XCOM_MOUNT_PATH}/return.json')
self._exec_pod_command(resp, 'kill -s SIGINT 1')
finally:
resp.close()
if result is None:
raise AirflowException(f'Failed to extract xcom from pod: {pod.metadata.name}')
return result
def _exec_pod_command(self, resp, command):
if resp.is_open():
self.log.info('Running command... %s\n', command)
resp.write_stdin(command + '\n')
while resp.is_open():
resp.update(timeout=1)
if resp.peek_stdout():
return resp.read_stdout()
if resp.peek_stderr():
self.log.info(resp.read_stderr())
break
return None
[docs] def process_status(self, job_id, status):
"""Process status information for the JOB"""
status = status.lower()
if status == PodStatus.PENDING:
return State.QUEUED
elif status == PodStatus.FAILED:
self.log.error('Event with job id %s Failed', job_id)
return State.FAILED
elif status == PodStatus.SUCCEEDED:
self.log.info('Event with job id %s Succeeded', job_id)
return State.SUCCESS
elif status == PodStatus.RUNNING:
return State.RUNNING
else:
self.log.error('Event: Invalid state %s on job %s', status, job_id)
return State.FAILED