change: check etcd cluster version when init_etcd

[tokers]

Signed-off-by: tokers zchao1995@gmail.com

What this PR does / why we need it:

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• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
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• Is this PR backward compatible?

[moonming]

the etcd in CI is 3.2, so failed: https://github.com/apache/apisix/pull/2233/checks?check_run_id=1116987808#step:6:288

[tokers]

@moonming It seems the version selection for etcd is not specified in ./bin/apisix or other stuffs. Is it under the Github Action's control?

[moonming]

we used to be the default version installed by github actions, now it is the etcd 3.4 version installed manually in #2036

[tokers]

@moonming OK, let me rebase my branch. By the way, i think it's better to check out the CHANGELOG of etcd, AKAIK there are some bugs in 3.x series releases, but i'm not sure the exact version range.

[tokers]

@moonming I found PR #2036 also checked the etcd version, but IMHO the way is wrong.

Firstly, when we ask the version message from etcd, it returns a JSON string like this:

{"etcdserver":"3.5.0-pre","etcdcluster":"3.5.0"}

we should check the version of etcdcluster, not the endpoint's server version (etcdserver) that we requested, the cluster version is the minimal server version of all endpoints in the cluster. So that's the one we need to check.

Secondly, the semantic version check method doesn't consider the pre release situation, although it's rare in prod, i think's better to consider it.

[moonming]

nice! we can fix it in this PR :) Thanks, Ming Wen Twitter: _WenMing Alex Zhang <notifications@github.com> 于2020年9月16日周三 上午10:36写道：

…

@moonming <https://github.com/moonming> I found PR #2036 <#2036> also checked the etcd version, but IMHO the way is wrong. Firstly, when we ask the version message from etcd, it returns a JSON string like this: {"etcdserver":"3.5.0-pre","etcdcluster":"3.5.0"} we should check the version of etcdcluster, not the endpoint's server version (etcdserver) that we requested, the cluster version is the minimal server version of all endpoints in the cluster. So that's the one we need to check. Secondly, the semantic version check method doesn't consider the pre release situation, although it's rare in prod, i think's better to consider it. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2233 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGJZBK5HWE4ZRBDK3NWH743SGAQERANCNFSM4RM3Y5IA> .

[tokers]

@membphis Fixed.

[Yiyiyimu]

@tokers Thank you for the fix!