### What changes were proposed in this pull request?
Remove environment variables `CELEBORN_MASTER_HOST` and `CELEBORN_MASTER_PORT`, and makes `CELEBORN_LOCAL_HOSTNAME` takes effect on both master and worker.
### Why are the changes needed?
There are many different ways to configure the master/worker host and port, which makes the thing complex and inconsistent.
After this change,
#### master
1. cli args `--host` `--port` takes the highest priority
2. then lookup env `CELEBORN_LOCAL_HOSTNAME`
3. things are different when HA enabled and disabled
3.1. when HA is disabled, lookup configurations `celeborn.master.host` and `celeborn.master.port`
3.2. when HA is enabled, each node needs to know the whole cluster info,
```
celeborn.master.ha.node.1.host clb-1
celeborn.master.ha.node.1.port 9097
celeborn.master.ha.node.2.host clb-2
celeborn.master.ha.node.2.port 9097
celeborn.master.ha.node.3.host clb-3
celeborn.master.ha.node.3.port 9097
```
in addition, `celeborn.master.ha.node.id=1` can be used to indicate the node id, otherwise, the master will try to bind each host to match the node id.
#### worker
1. cli args `--host` `--port` takes the highest priority
2. then lookup env `CELEBORN_LOCAL_HOSTNAME`
things are simple than the master case because each worker is not required to know others.
### Does this PR introduce _any_ user-facing change?
Yes.
### How was this patch tested?
UT.
Closes#1616 from pan3793/CELEBORN-707.
Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: zky.zhoukeyong <zky.zhoukeyong@alibaba-inc.com>
### What changes were proposed in this pull request?
Extend doc about migration from 0.2.1 to 0.3.0. Added the following contents:
<img width="1084" alt="image" src="https://github.com/apache/incubator-celeborn/assets/26535726/7a9d172c-09ba-48b6-9f5c-73a8b13d035f">
### Why are the changes needed?
ditto
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
No.
Closes#1612 from waitinfuture/702.
Lead-authored-by: zky.zhoukeyong <zky.zhoukeyong@alibaba-inc.com>
Co-authored-by: Cheng Pan <pan3793@gmail.com>
Signed-off-by: zky.zhoukeyong <zky.zhoukeyong@alibaba-inc.com>
### What changes were proposed in this pull request?
It was discussed during the last meeting, but abandoned due to the complication.
### Why are the changes needed?
Make the configuration unified.
### Does this PR introduce _any_ user-facing change?
Yes, but the legacy configurations still take effect.
### How was this patch tested?
New UTs.
Closes#1549 from pan3793/CELEBORN-638.
Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: zky.zhoukeyong <zky.zhoukeyong@alibaba-inc.com>
### What changes were proposed in this pull request?
Refresh celeborn configurations in doc
### Why are the changes needed?
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
Closes#1592 from AngersZhuuuu/CELEBORN-680.
Authored-by: Angerszhuuuu <angers.zhu@gmail.com>
Signed-off-by: Angerszhuuuu <angers.zhu@gmail.com>
