wangyang0918 opened a new pull request #14629:
URL: https://github.com/apache/flink/pull/14629
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## What is the purpose of the change
Now the native K8s integration is almost production ready. We already have
the common features for deploying a Flink cluster on K8s cluster natively.
However, compared with the current supported features[1] in
flink-on-k8s-operator and the feedback from users(ML and JIRAs), I am afraid
that we still need some advanced features.
* Init containers[2]
* Sidecar containers[3]
* Arbitrary volume(PVC, hostpath, emptyDir, ConfigMap) mount[4]
* Set owner reference for the JobManager deployment[5]
* Support customizing of containers for native kubernetes setup[6]
* Pod Affinity and Anti-affinity
* Pod Security Context
* Pod Environment Variables Reference
So this PR tries to introduce a pod template[7] for all the use cases. Users
could configure a local yaml file for JobManager/TaskManager. This will let
Flink create the JobManager/TaskManager pods with the template first, not the
empty. Of course, the Flink config options for Kubernetes[8] have high priority
and could overwrite these values.
Pod template is is a typical pod yaml. You could set arbitrary fields that
is supported by K8s directly. The following is a simple example, which add the
init container, sidecar container and volume mount.
```
apiVersion: v1
kind: Pod
metadata:
name: pod-template
spec:
initContainers:
- name: artifacts-fetcher
image: busybox
imagePullPolicy: IfNotPresent
# Use wget or other tools to get user jars from remote storage
command: ['wget',
'https://flink-debug-yiqi.oss-cn-beijing.aliyuncs.com/StateMachineExample.jar',
'-O', '/flink-artifact/myjob.jar']
volumeMounts:
- mountPath: /flink-artifact
name: flink-artifact
containers:
# Do not change the main container name
- name: flink-job-manager
volumeMounts:
- mountPath: /opt/flink/volumes/hostpath
name: flink-volume-hostpath
- mountPath: /opt/flink/usrlib
name: flink-artifact
- mountPath: /opt/flink/log
name: flink-logs
# Use sidecar container to push logs to remote storage or do some other
debugging things
- name: sidecar-log-collector
image: busybox
imagePullPolicy: IfNotPresent
args:
- tail
- -F
- /flink-log/jobmanager.log
volumeMounts:
- mountPath: /flink-log
name: flink-logs
volumes:
- name: flink-volume-hostpath
hostPath:
path: /tmp
type: Directory
- name: flink-artifact
emptyDir: {}
- name: flink-logs
emptyDir: {}
```
[1]. https://github.com/GoogleCloudPlatform/flink-on-k8s-operator#features
[2]. https://issues.apache.org/jira/browse/FLINK-15641
[3]. https://issues.apache.org/jira/browse/FLINK-15871
[4]. https://issues.apache.org/jira/browse/FLINK-15649
[5]. https://issues.apache.org/jira/browse/FLINK-20359
[6]. https://issues.apache.org/jira/browse/FLINK-20324
[7]. https://issues.apache.org/jira/browse/FLINK-15656
[8].
https://ci.apache.org/projects/flink/flink-docs-master/deployment/config.html#kubernetes
## Brief change log
* Introduce the pod template
## Verifying this change
* All the new introduced functionalities are covered by new added unit test
* Manually testing
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (yes / **no**
/ don't know)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (**yes** / no /
don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (**yes** / no)
- If yes, how is the feature documented? (Will add a detailed
documentation about how to use pod template in a following PR)
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