resource version reset default when event object resource version inv…

[DrAuYueng]

Watch an API resource and stream the result back via a generator, when resource_version specified, may be cause "too old resource version" error, then result would be:
{ "type":"ERROR", "object":{ "kind":"Status", "apiVersion":"v1", "metadata":{ }, "status":"Failure", "message":"too old resource version: 38081900 (64845263)", "reason":"Gone", "code":410 } }
In this case, the func unmarshal_event can not parse the right resource version, actually is None,
the stream while loop continue, the next request will get ApiException: (500) error:
HTTP response headers: HTTPHeaderDict({'Content-Length': '186', 'Content-Type': 'application/json', 'Date': 'Fri, 19 Jun 2020 06:21:06 GMT'}) HTTP response body: b'{"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"resourceVersion: Invalid value: \\"None\\": strconv.ParseUint: parsing \\"None\\": invalid syntax","code":500}\n'

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[DrAuYueng]

@yliaog

[codecov-commenter]

Codecov Report

Merging #199 into master will increase coverage by 0.42%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #199      +/-   ##
==========================================
+ Coverage   92.23%   92.66%   +0.42%     
==========================================
  Files          13       13              
  Lines        1481     1554      +73     
==========================================
+ Hits         1366     1440      +74     
+ Misses        115      114       -1     

Impacted Files	Coverage Δ
watch/watch.py	100.00% <100.00%> (ø)
config/kube_config.py	83.29% <0.00%> (-0.20%)	⬇️
config/kube_config_test.py	95.76% <0.00%> (+0.16%)	⬆️
config/incluster_config_test.py	97.84% <0.00%> (+0.55%)	⬆️
config/incluster_config.py	95.45% <0.00%> (+10.34%)	⬆️

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[DrAuYueng]

kubernetes version：v1.14.6

[roycaihw]

/cc

[roycaihw]

Watching with resourceVersion=0 doesn't guarantee the client to continue watching from the last seen state, and therefore may cause missing watch events. The right way to handle a 410 Gone response is to perform a LIST request, and start the watch from the resourceVersion returned by that new list operation (see https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes for more details).

This is part of the problems kubernetes-client/python#868 was trying to address

[DrAuYueng]

If catch event type of Error and continue like #133 ,will cause endless loop, current resourceVersion never change, always get Error of message:"too old resource version"

[DrAuYueng]

If catch event type of Error and continue like #133 ,will cause endless loop, current resourceVersion never change, always get Error of message:"too old resource version"

Make resourceVersion=0 make sure the watch stream still work even if the wrong init resource version set

[roycaihw]

will cause endless loop, current resourceVersion never change, always get Error of message:"too old resource version"

I don't think that's what we want and it should not happen

perform a LIST request, and start the watch from the resourceVersion returned by that new list operation

the resourceVersion returned by a LIST request will be the latest resourceVersion, it won't be stale

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@fejta-bot: Closed this PR.

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