Introduce a friendly way to resume the job from externalized checkpoints automatically

I know a flink job can reovery from checkpoint with restart strategy, but can not recovery as spark streaming jobs when job is starting.

Every time, the submitted flink job is regarded as a new job, while , in the spark streaming  job, which can detect the checkpoint directory first,  and then recovery from the latest succeed one. However, Flink only can recovery until the job failed first, then retry with strategy.

So, would flink support to recover from the checkpoint directly in a new job?

New description by sihuazhou

Currently, it's quite a bit not friendly for users to recover job from the externalized checkpoint, user need to find the dedicate dir for the job which is not a easy thing when there are too many jobs. This ticket attend to introduce a more friendly way to allow the user to use the externalized checkpoint to do recovery.

The implementation steps are copied from the comments of StephanEwen:

• We could make this an option where you pass a flag (-r) to automatically look for the latest checkpoint in a given directory.
• If more than one jobs checkpointed there before, this operation would fail.
• We might also need a way to have jobs not create the UUID subdirectory, otherwise the scanning for the latest checkpoint would not easily work.