add a label key: TaskIndexKey = volcano.sh/task-index

[shuaiyy]

the task pod has a label of task spec by TaskSpecKey = "volcano.sh/task-spec",
while task index missed, it's useful for pod lbael selectors to select a task pod by it's spec and index

the issue is here: add label key volcano.sh/task-index #98

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[hwdef]

I don't quite understand this requirement. Do you have a more detailed explanation? Is there any place where this field is used?

[shuaiyy]

I don't quite understand this requirement. Do you have a more detailed explanation? Is there any place where this field is used?

I have updated the description.

task-index info will be set to task pod's label, it has been set to container env key VC_TASK_INDEX by env plugin, but missed in pod labels.

[Thor-wl]

task-index info will be set to task pod's label, it has been set to container env key VC_TASK_INDEX by env plugin, but missed in pod labels.

Can you provide the original requirement? Yes, this key has been added into the environment variables.

[shuaiyy]

task-index info will be set to task pod's label, it has been set to container env key VC_TASK_INDEX by env plugin, but missed in pod labels.

Can you provide the original requirement? Yes, this key has been added into the environment variables.

Okay. I'm trying to use volcano to replace kubeflow training-operator in my ml-platform; the training-operator provide job-name|task-spec|task-index label in task pod, while volcano missed task-index.

our ml-platform need these label：

1. mount env key TASK_INDEX, the key is used by users and it's hard to let them change to VC_TASK_INDEX
2. create a service with pod selector for a spectific task pod, and then create an ingress; if users need to debug their task by http tools;
3. watch task pod's change and sync some info to persist db.

in our scenes, the use of task-index label may not common to other volcano users, but I do think the pod label info task-index is common, should be provided no matter how users will use it