Support data source integrate with spring cloud config

[linlinisme]

###Describe what this PR does / why we need it

Now, data source support nacos,zeepkeeper,redis and so on.The spring-cloud-config also should be.

Does this pull request fix one issue?

Fix issue: #831

Describe how you did it

My proposal is based on spring cloud config original loading mechanism.
The PropertySourceLocator Interface : provides external attribute loading extension points.

Any class implements PropertySourceLocator interface and modified with corresponding annotation.
It will be loaded by org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration and invoke the org.springframework.cloud.bootstrap.config.PropertySourceLocator#locate to pull configurations from remote server. The spring-cloud-config example is org.springframework.cloud.config.client.ConfigServicePropertySourceLocator

All I do it is reference ConfigServicePropertySourceLocator build another client which can integrate with sentinel data source and support dynamic refresh.

It's name is com.alibaba.csp.sentinel.datasource.spring.cloud.config.SentinelRuleLocator. It will be created when spring application start and pull configurations. It supply refresh method to support dynamic refresh function.

Describe how to verify it

In sentinel-extension/sentinel-datasource-spring-cloud-config/src/test package, there is a ConfigServer and ConfigClient. You should start the ConfigServer first. It will connected my git warehouse. If you want to use another, modify config-server-application.properties file. Then you can run SentinelRuleLocatorTests. The ConfigClient also can test function. When you start ConfigClient , remember that rename client-bootstrap.yml to bootstrap.yml.Then you can through SpringCouldDataSourceTestController to test SpringCloundConfigDataSource.
The page access url is : localhost:8080/index

Special notes for reviews

If this proposal is ok, more test cases and readme file will be provided later

[codecov-io]

Codecov Report

Merging #899 into master will decrease coverage by 0.26%.
The diff coverage is 28.4%.

@@             Coverage Diff              @@
##             master     #899      +/-   ##
============================================
- Coverage     42.74%   42.48%   -0.27%     
- Complexity     1450     1458       +8     
============================================
  Files           311      315       +4     
  Lines          9047     9223     +176     
  Branches       1228     1258      +30     
============================================
+ Hits           3867     3918      +51     
- Misses         4706     4814     +108     
- Partials        474      491      +17

Impacted Files	Coverage Δ	Complexity Δ
...ring/cloud/config/SpringCloudConfigDataSource.java	0% <0%> (ø)	0 <0> (?)
...ource/spring/cloud/config/SentinelRuleStorage.java	0% <0%> (ø)	0 <0> (?)
...onfig/config/DataSourceBootstrapConfiguration.java	100% <100%> (ø)	2 <2> (?)
...ource/spring/cloud/config/SentinelRuleLocator.java	35.87% <35.87%> (ø)	5 <5> (?)
...ava/com/alibaba/csp/sentinel/node/ClusterNode.java	100% <0%> (+4.76%)	8% <0%> (+1%)	⬆️

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[sczyh30]

Would you like to provide some suggestions on this? @fangjian0423

[linlinisme]

hi, is there some progress?
 

[sczyh30]

hi, is there some progress?

I've reviewed the code last week, and I'll need to test the sample these days :)

[sczyh30]

Nice work. I'm wondering how this could achieve dynamic updating? It seems when the content of PropertySource is updated, the property inside the SpringCloudConfigDataSource is not notified (via updateValue)?

[linlinisme]

Nice work. I'm wondering how this could achieve dynamic updating? It seems when the content of PropertySource is updated, the property inside the SpringCloudConfigDataSource is not notified (via updateValue)?

They dynamic updating function is based on the Web Hook call back. When you change config in the Server does you setting Web Hook call back url ? I offer a test in com.alibaba.csp.sentinel.datasource.spring.cloud.config.test.SpringCouldDataSourceTest#refresh 。Actually the dynamic updating function need users develop a call back function, but it is simple :), and we can offer the sample to them.

[linlinisme]

Nice work. I'm wondering how this could achieve dynamic updating? It seems when the content of PropertySource is updated, the property inside the SpringCloudConfigDataSource is not notified (via updateValue)?

listener had added

[sczyh30]

How could the client perceive that the remote config has changed? By binding a git webhook with the refresh API?

[linlinisme]

How could the client perceive that the remote config has changed? By binding a git webhook with the refresh API?

Yes, it is.

[linlinisme]

some process?

[sczyh30]

How could the client perceive that the remote config has changed? By binding a git webhook with the refresh API?

Yes, it is.

Could you please add a brief instruction for this in the document?

[sczyh30]

LGTM

[sczyh30]

Nice work. Thanks for contributing!