refactor: add etcd_connect_options for metasrv

[zyy17]

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What's changed and what's your intention?

The original create_etcd_client() uses None for ConnectOptions and can't configure some important arguments for connecting etcd.

In this PR, I created the EtcdConnectOptions, a subset of ConnectOptions, in the MetasrvOptions. I also added the covert function to let EtcdConnectOptions convert ConnectOptions easily.

btw, it's convenient to add TLS configurations in the future in the same structure(I will add it in the next PR).

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[tisonkun]

This option itself can be Option? Or we define a etcd subsection for metasrv. Extending this option looks like we leak/couple the metasrv with etcd implementation.

[zyy17]

It seems reasonable. It also reminds me that there is more than one option for metasrv backend storage in the future(file system, memory, etcd, ...). I think we need the BackendStorageProvider and etcd is one of the providers.

For example:

[storage]
type = "etcd"
addr = "127.0.0.1:2379"
timeout = "5s"

What do you think? @fengjiachun

[fengjiachun]

It seems reasonable. It also reminds me that there is more than one option for metasrv backend storage in the future(file system, memory, etcd, ...). I think we need the BackendStorageProvider and etcd is one of the providers.

For example:

[storage]
type = "etcd"
addr = "127.0.0.1:2379"
timeout = "5s"

What do you think? @fengjiachun

+1

[codecov]

Codecov Report

Attention: Patch coverage is 10.52632% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 85.28%. Comparing base (2748cec) to head (69dec61).

Additional details and impacted files

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##             main    #3853      +/-   ##
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- Coverage   85.60%   85.28%   -0.33%     
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  Files         955      955              
  Lines      163262   163278      +16     
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- Hits       139764   139245     -519     
- Misses      23498    24033     +535     

[zyy17]

Let me refactor again for adding the BackendStorageProvider.

[zyy17]

Close it temporarily. I will re-open it when the PR is ready for review.